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diff --git a/old/60765-0.txt b/old/60765-0.txt deleted file mode 100644 index 6cff091..0000000 --- a/old/60765-0.txt +++ /dev/null @@ -1,7668 +0,0 @@ -The Project Gutenberg EBook of The Young Mechanic, by James Lukin - -This eBook is for the use of anyone anywhere in the United States and most -other parts of the world at no cost and with almost no restrictions -whatsoever. You may copy it, give it away or re-use it under the terms of -the Project Gutenberg License included with this eBook or online at -www.gutenberg.org. If you are not located in the United States, you'll have -to check the laws of the country where you are located before using this ebook. - -Title: The Young Mechanic - -Author: James Lukin - -Release Date: November 22, 2019 [EBook #60765] - -Language: English - -Character set encoding: UTF-8 - -*** START OF THIS PROJECT GUTENBERG EBOOK THE YOUNG MECHANIC *** - - - - -Produced by Chris Curnow and the Online Distributed -Proofreading Team at http://www.pgdp.net (This file was -produced from images generously made available by The -Internet Archive) - - - - - - - - - - - THE - YOUNG MECHANIC - - CONTAINING - _DIRECTIONS FOR THE USE OF ALL KINDS OF TOOLS_, - AND FOR THE - _CONSTRUCTION OF STEAM ENGINES AND - MECHANICAL MODELS_, - INCLUDING - _THE ART OF TURNING IN WOOD AND METAL_. - - BY THE - AUTHOR OF “THE LATHE AND ITS USES” - “THE AMATEUR MECHANIC’S WORKSHOP,” &c. - - _FROM THE ENGLISH EDITION, WITH CORRECTIONS, &c._ - - G. P. PUTNAM’S SONS - - NEW YORK - 27 WEST TWENTY-THIRD ST. - - LONDON - 24 BEDFORD ST., STRAND - - The Knickerbocker Press - - 1896 - - Entered according to Act of Congress, in the year 1871, by - G. P. PUTNAM & SONS, - in the Office of the Librarian of Congress at Washington. - - - - -INTRODUCTION TO THE AMERICAN EDITION. - - -In presenting the American edition of this little work to the public, -we believe we are supplying a want that has long been felt by the Young -Mechanics of this country, and many others who desire to become versed in -the practical use of tools. We know of no other book published in this -country or England, in which the method of using tools is so clearly -explained; and although written more especially for boys and beginners, -it contains much information that will be of great value to the practical -mechanic. The author is evidently thoroughly acquainted with his subject, -and understands how to communicate his ideas in a simple and concise -manner. - -The first six chapters are devoted to the description of Tools for -working wood and the manner of using them, beginning with the simplest -operations, requiring but few tools, and gradually leading on to the more -difficult, giving examples of all the methods of joining and finishing -work that are in common use among good workmen, and in this connection -we would like to call attention to the small number of tools the author -requires for performing all these different operations, the idea among -amateurs and boys generally being, that if you only have tools enough you -can make anything. This is not so, and if the beginner will follow the -advice of the author, and buy a few good tools, and learn the use of them -thoroughly, and gradually add to his stock as his knowledge of their use -increases, he will find it greatly to his advantage. - -The next five chapters relate to the lathe, and the art of turning. -The author follows the same plan as in the first part of the book, and -gives more practical information in these few pages than we have seen -in any other book on the subject, most of them being written apparently -for finished mechanics, and not for beginners. The Art of Turning as -an amusement, is beginning to attract considerable attention in this -country, but not so much as it deserves and would obtain, if it were -more generally known how many beautiful and useful articles can be -produced in the lathe. The expense of the necessary tools has deterred -many from attempting to learn this branch of mechanics; but we believe if -any one has the time and patience to devote to the work, they will never -have occasion to regret the money spent for this purpose. - -The last four chapters contain practical instruction in model-making and -working in metal. This part of the book we would particularly recommend -to inventors who desire to make their own models, as it contains -information in regard to files, drills, and the various small tools used -on metal, and also directions for laying out work, which are invaluable -to a novice in such operations, and will save him much time and trouble. - -As this book was originally published in London, where the facilities -for getting many kinds of small tools are better than in this country, -perhaps a little advice as to the best way of getting such tools as may -be required will not be out of place. In most of the large Hardware -Stores, carpenters’ tools will be found, put up in chests, at prices -varying from five to fifty dollars or more; but we should not advise the -amateur to buy any of these, as the quality of the tools is not always -reliable, and as they are usually fitted up to make as much show as -possible for the money, they contain many tools which are of very little -use. The best way is to make a list of the tools required, and select -them for yourself. The most important thing is to have the Cutting tools -of good quality. We give below the names of some of the best makers of -tools; if you purchase any of these, you may be sure of the quality. - - On Saws,—HENRY DISSTON, GROVES & SON. - On Chisels and Gouges,—BUCK BROS., MOULSON BROS. - On Plane Irons,—MOULSON BROS., WM. BUTCHER. - On Files,—P. S. STUBS, GREAVES & SON, EARL & CO. - On Rules and Squares,—STANLEY RULE AND LEVEL CO. - -If you live in the City, you will probably find no difficulty in -procuring some of the above makes; but if you cannot find them there are -some others that are good, and you must rely somewhat on the dealer. In -regard to the probable cost of the tools, a set such as is described on -pages 29 and 30, would cost from fifteen to twenty dollars. - -Of Foot Lathes, the following are some of the makers: - - N. H. BALDWIN, Laconia, N. H. - GOODNOW & WIGHTMAN, Boston, Mass. - AMERICAN TOOL CO. ” ” - G. L. CADY, Lowell, Mass. - EXETER MACHINE CO., Exeter, N. H. - JAS. STEWART’S SONS, New York. - -From some of the above the amateur will probably be able to select -a Lathe to suit him in size and price. The lowest price at which a -serviceable lathe can be bought is about forty dollars this is without -tools or chucks. About fifteen dollars more would be required for -these. Lathes can be bought from this price up to hundreds of dollars, -according to the style of lathe and the number of chucks, but of course -the beginner would not need an expensive lathe, and seventy-five to one -hundred dollars would buy a lathe and tools suitable for all kinds of -small work in wood, ivory, or metal. - - This volume being an exact reprint of the English edition, - it may be well to explain that the material called _Deal_ in - England is much the same as our _Pine_. The article called in - England a “Carrier,” is with us called a _dog_ (see pp. 112, - 114, 115). Articles priced in English currency would cost here - now about 35 cents to the English shilling, or $7 per £ stg. - - - - -PREFACE. - - -Of all people in the world who must not be neglected are, first and -foremost, “Our Boys,” and, of all boys, _mechanical boys_ deserve a very -high place in our estimation. Whatever others may be, these, at any rate, -are possessed of sound heads, and willing hands. Therefore, to help these -to carry out their designs, appears to be a special duty of those who, -once mechanical boys themselves, have lived to become the progenitors of -others. In fulfilment of this very duty I have taken up the pen, and with -special reference to _young_ mechanics, but without entirely forgetting -those of maturer growth, I have thrown together a few hints upon that -absorbing question, “How to make and how to use?” In doing this, I have -endeavoured to carry out the plan of _small beginnings_, going from -the simplest and easiest to the more complicated and difficult work, -although here and there, of sheer necessity, a somewhat different order -has been observed. The workshops of King’s College School prove the -capabilities of boys to do high-class mechanical work when their efforts -are rightly directed by a master’s hand. Where the latter cannot be -obtained, guide-books must, however insufficiently, take his place; but -whether instruction in mechanical art be oral or otherwise, practice and -perseverance are the secrets of success. - - “Qui studet optatam cursu contingere metam, - Multa tulit fecitque puer; sudavit et alsit.” - - - - -CONTENTS. - - - CHAP. PAGE - - I. INTRODUCTORY, 1 - - II. HOW TO MAKE A CAGE, 15 - - III. MORTICE AND TENON JOINTING, 29 - - IV. HOW TO MAKE A TABLE, 49 - - V. DOVETAILING AND MITRING, 66 - - VI. REBATING, TONGUEING, AND GROOVING, 89 - - VII. THE YOUNG MECHANIC AT THE LATHE, 103 - - VIII. ON WOODS AND MATERIALS FOR TURNING, 122 - - IX. SHARPENING AND SETTING TOOLS, 144 - - X. HAND-TURNING IN WOOD, 163 - - XI. HARD-WOOD TURNING, 203 - - XII. HOW TO MAKE A STEAM-ENGINE, 226 - - XIII. WATT’S ENGINE, 264 - - XIV. HOW TO MAKE AN ENGINE, 281 - - XV. HARDENING AND TEMPERING TOOLS, 325 - - - - -CHAPTER I. - - -There never was a time when a taste for practical mechanics was so -general among boys as it is now, in this year of grace 1870. There are -comparatively few homes in which evidences of this hobby are not apparent -in every odd nook and corner, in the shape of carpenter’s tools, not -always in first-rate condition, nor by any means generally in their -proper places. A saw here, a hammer there, a gimlet, bradawl, or chisel -elsewhere. - -This probably results from the giant strides which have been made of -late years in mechanical enterprise, and the introduction of machinery -into every department, as a means of saving labour and facilitating the -production of the various necessaries of life. - -Man is an imitative animal, and in this as in other things “the child -is father to the man;” and hence it comes to pass that the boy whose -eyes are continually resting upon machinery of one sort or another -(agricultural implements, if a villager; engines for planing, sawing, -turning, and so forth, if resident in a town) sooner or later feels an -innate desire to construct models of these gigantic mechanical labourers, -by whose incessant but unfelt toil our several daily needs are so cheaply -and plentifully supplied. - -Even if the youthful mind does not always display highly-developed -inventive faculties, there is very generally manifested a desire of -personally constructing some one or more of those articles which conduce -to the gratification of a particular hobby. If the boy has a taste for -natural history, cases and cabinets will be made, for the reception -of eggs, butterflies, and insects, or to contain stuffed specimens of -animals and birds. If he has within him the elements of a sailor, his -ingenuity will be exercised upon model boats and ships. If fond of dumb -pets, rabbit hutches, dove-cots, or cages will afford him opportunities -for the exercise of his constructive powers, and thus the young mechanic -frequently lays the foundation of future eminence in that particular line -of life to which his tastes naturally lead him. - -There are few boyish hobbies in which assistance has not of late -years been given by instruction books and guides of a high degree of -excellence—natural history, botany, gardening, rearing and breeding all -manner of pets—to each of these, well-written volumes have been devoted -by able and experienced writers, but mechanical and constructive art -has been somewhat neglected. Here and there, in periodical magazines, -a few pages are dedicated to the subject, but no book about practical -mechanics, written expressly for boys, has yet appeared. - -The author of the present volume, himself father of four lads, _all_ of -whom in turn occasionally try their hands at this kind of work, and who -has himself for many years practised the mechanical arts of carpentry, -turning, and model-making, hopes that the hints contained herein may -prove valuable to those young friends whom he now addresses. Some of -the following chapters will be arranged for very little boys, some for -those who are older, while it is believed that other parts of the work -may not prove altogether useless to those who have dropped jacket and -knickerbockers and rejoice in the vigour of manhood. Thus the little boy, -who receives the book as a present, will find it a fast and faithful -friend as his years, and, we trust, knowledge and bodily powers increase. - -“_Small boys need few tools, but much perseverance._” Let this be their -motto, as it will stand them in good stead. A pocket-knife, gimlet, -hammer, and a few nails will generally serve their purpose; but there is -one other tool, namely, a square, which is of great importance, and of -which it is well to learn the use as early as possible. A small saw and -a bradawl may also be added to the list, and likewise a chisel half an -inch wide. Thus equipped, a very youthful carpenter can do a good deal, -and, let me tell him, a good deal has been often done without even this -moderate supply of tools. It must be taken for granted that the knife and -chisel are sharp, because blunt tools make bad work, and by far the best -plan for small boys is to get some friend to sharpen them when blunt, as -the operation is not easy and requires practice. It is a very foolish -plan to try and work with a blunt knife, for the fingers are just as much -in danger; and a boy who intends to learn how to use tools must learn at -the commencement to use them with due care, so as not to damage himself. - -There are small boxes of tools sold, containing generally a wooden -mallet, saw, plane, chisel, and gimlet, at about 3s. 6d. or even 5s. Such -a box is simply useless. The tools are of iron—will not take a good edge, -and are generally disposed to bend and twist. Avoid these, and buy, or -get a friend to buy, those I have named, of good quality, and be sure to -take care of them, for which purpose you may try your hand at making a -box. For this purpose, you will require some thin board (half-inch thick) -planed on both sides. (The carpenter will prepare this for you.) Let us -see how much you will need. Measure your longest tool, the chisel or -saw, if the latter is quite a small one fit to go into a little box; if -not, it can be hung on a nail, and you can make your box to contain your -knife and chisel and gimlets. I daresay if the box is 9 inches long, 4 -inches wide, and 3 inches deep, it will be large enough to take these few -tools, for I have just now measured such a hammer and chisel as I have -recommended, and find them each about 9 inches in length. The top and -bottom of a box should project a little all round, so that you will want -them about an inch and a half wider and longer, which will also allow for -the thickness of the wood; for you must remember we have given the size -of the box _inside_. To make this clear, I shall here give a plan of the -bottom of the box (Fig. 1). - -[Illustration: Fig. 1.] - -[Illustration: Fig. 2.] - -[Illustration: Fig. 3.] - -It is 10½ inches long, and 5½ inches wide. The broad black line shows -where the edges of the sides and ends will come, these being half an inch -thick, so that there is a quarter of an inch all round the outside as a -border. Reckon across and you will understand this better. A quarter of -an inch outside, half an inch for the black line (equals three-quarters -of an inch), 4 inches for the _inside_ width, half an inch again for the -black line, and a quarter of an inch outside as before,—altogether making -5½ inches. Now reckon the length. A quarter-inch border, half an inch for -the black line, 9 inches inside, half inch for the second black line, -and another quarter outside—making 10½ inches. You require, therefore, -two boards 10½ inches long and 4½ wide for the top and bottom. Now the -two long sides and the ends are to be 3 inches wide to form the depth of -the box, and here you want no extra _width_, but as the _inside_ of your -box is to be 9 inches long, and the sides are usually nailed over the -ends, like Fig. 2, where I have shown them put together, you see that you -must have the _sides_ as much longer than 9 inches as will allow them to -lap over the ends; that is, half an inch at each end where I have made -them black, or altogether, one inch; so that you will want two pieces 10 -inches long and 3 wide. The ends will be also 3 inches wide and 4 inches -the other way, and here no additional size is needed. Now, the usual way -to cut the sides is to get a narrow strip of board of the required width -and thickness, and long enough to make both the sides and ends, just such -a piece as Fig. 3, on which are marked the lines where it will have to be -cut across, and you will easily perceive that you require 28 inches in -length and 3 in width. - -But you must understand that when you cut with a saw you waste a little -of the wood, which falls in the shape of sawdust, and so if you did not -allow for this, your box would be too small. The waste depends on the -thickness of the edge of the saw, where you will, if you examine it, see -that the teeth spread out right and left to prevent it from sticking -fast as it is used. Probably, you would waste three-eighths of an inch, -which is nearly half an inch in cutting off the pieces, so that instead -of a piece exactly 28 inches long, you must have it 28½ inches, or even a -little more. - -I want you to understand all this before you set to work, even though at -first you may get a carpenter to measure and cut it for you; because most -small boys take no trouble of this kind, and consequently they are sure -to make their boxes too large or too small, and they look very bad when -done. However, as I said before, I expect my young readers to understand -what they are about, and they must set out their work carefully, or they -will never get on so as to be able to make good use of the later chapters -of this book. A carpenter’s rule is made like this (Fig. 4). - -[Illustration: Fig. 4.] - -Sometimes there is a brass slide, to add to its length when necessary, -and sometimes it is hinged so as to fold up again. If you want one for -your box, you can get it so made, when it will go in nicely. It is 2 -feet long—1 foot on each side of the central joint. A foot is 12 inches; -the whole rule, therefore, is 24 inches. Now, you will see that each of -these inches is divided by short lines into eight equal parts, called -eighths; at the second, the line is rather longer, this being a quarter -of an inch; at the fourth, there is a still longer line, this being the -half-inch; then comes another eighth, then the three-quarters, another -eighth, and the inch is made up,—eight-eighths being equal to one whole -inch. Very likely you will find one _edge_ of the rule, or sometimes -only one _inch_, divided into smaller parts, which are sixteenths, -or half-eighths; and sometimes, but not very often, divisions still -smaller are used, which are half-sixteenths, or thirty-seconds, because -thirty-two such divisions make the complete inch. Three feet make one -yard, but carpenters always reckon by the foot and inch, and by eighths -and sixteenths of an inch. In some trades the inch is divided into a -_hundred_ parts, and work is measured up and fitted so carefully, that it -would be considered faulty if a mistake of less than a _thousandth_ of an -inch were made; but you will not yet understand how it is possible even -to _measure_ so very small a quantity. You should certainly learn and -understand how to measure with a common two-foot rule, and when you can -add one to your box of tools, do so. - -Now, let us examine the tool called a square, without which the marks -could not readily be drawn as a guide for the saw, where the strip of -board is to be cut to make the sides and ends of the proposed box. Here -is a drawing of one (Fig. 5). - -[Illustration: Fig. 5.] - -[Illustration: Fig. 6.] - -It is a handle and a blade, like a knife half opened, the one being -fixed exactly square, or at right angles with the other. The blade is -thinner than the handle, and when the latter is placed as in Fig. 6, -a line marked across the board against the edge of the blade will be, -of course, square to the side, so that when cut off, the piece will be -like the end of Fig. 6. This is not the shape which the sides of boxes -generally have when made by small boys, because they have not a square, -and do not know how to work properly. Nevertheless, if _one_ end of a -board is cut square, you might get the piece right by measuring the same -distance on each side (say 10½ inches), and drawing a line across from -point to point, as a guide for the course of the saw. But, then, as it is -absolutely necessary that the end of the board should be square to the -side, to do this you had better get a proper square at once, and learn -how to use it. You will, indeed, find this tool most necessary for all -kinds of work, and you will be quite unable to do without it, even though -you only have, besides, a knife and gimlet. - -Now, if you want to cut off a piece of board with the saw, you must -_never cut out the line you have marked as a guide by the help of your -square_, because if you do, you will get the piece too short, owing to -the width of the saw-cut which I explained before. Cut, therefore, _just_ -beyond it, leaving it upon the piece you are going to use for the side -of your box, or other article. At first, you will find it difficult to -saw neatly and close to the line, but you will get used to it very soon; -and if the saw does not go quite straight, you can trim the piece with -a sharp knife neatly up to the line, which you see you could not do if -you cut out that line by sawing exactly upon it. All these directions -in little matters are very important, because you will find that, by -attending to them, you will work well, and the various things you make -will look neat and trim, and be fit to show to your friends. - -Now, let us go on with the box, which was laid down just to allow a -little explanation about the carpenter’s rule and square. I shall suppose -you to have cut off all the pieces quite squarely and neat, and that the -_edges_ are also square to the sides, which you must take care to insure -by keeping the blade of the saw upright when you use it. It is a good -plan to measure and mark _both_ sides of your board for this purpose, and -to mark the edges from one of these lines to the other. You will then -have guide-marks all round, and, by keeping close to these, you will be -sure to cut your work truly. It would not so much signify if the long -sides were cut a trifle _too_ long, as I shall explain presently; but the -_ends_ must be square and true to measure, 4 inches by 3 inches. You must -now proceed to nail them together. This must be done with small _brads_, -which are fine nails, and which for the present purpose may be one inch -long. If your pieces are all exact to measure, draw a pencil line across -the two side pieces, a quarter of an inch from the ends, by the help of -the square, as if you wanted to cut off a quarter of an inch at each of -those parts, and with your bradawl make two or three holes (three will -be best) along those lines. Do not make the first and last too near the -edges, or you will split the wood, and spoil the box. Now set up one of -the short pieces, and place upon it the piece which you have bored holes -in. If you have a bench with a vice, you can screw up the short piece -into it; but it will stand up very well upon the bench if you have no -vice. It is now in the position of Fig. 7, C. - -[Illustration: Fig. 7.] - -Hold it thus, and run the bradawl a little way into the lower piece, -through the holes already made in the upper. Drive a brad through the -middle hole first, which will hold it together, and then through the -other two holes. If you have been careful, you will find this corner -square and neat, and the wood not split in the least. Do the same with -the other short piece, and then nail on the long side that is left. The -frame of the box will now be complete. - -I told you a short time ago, that it would not much signify if the -_sides_ were cut too long. The reason is this: Suppose B to be the side -half an inch too long. You would mark off 9 inches of the middle by two -lines drawn with the square as before, which would be the length of the -_inside_ of the box; you would then place the inner edges of the end -pieces against these lines, and nail them on like A, and afterwards -neatly saw off the two pieces which lap over these at each end. If the -wood is likely to split when the holes are made for the nails, or if the -workman is pressed for time, he very frequently does his work in this -way, and then cuts it off and planes it neatly. It is, however, better to -work as directed, only be sure to bore holes carefully for the nails, so -as never to split the wood. - -No very special directions are needed about putting on the bottom. Leave -all round an exactly even border of a quarter of an inch, and after it -is nailed, you may neatly round off all its edges, to give it a finished -appearance. - -The cover is, of course, to be attached by a pair of small hinges. Brass -hinges are the neatest, and when you buy them, ask for screws to match. -The hinges may be three-quarters of an inch long, and they will be, when -shut, about half an inch wide, which is the size you need. Lay them -(shut up) upon the edge of the back, about two inches from the ends, -and with a hard pencil cut to a fine point, or with the point of your -bradawl, make a mark at each end, as if you were measuring the length of -the hinges on the edge of the box. Between these marks you have to cut -out pieces like Fig. 8, which will be just the length of the hinges, and -deep enough to allow them, when shut up, to fit and lie even with the -top edge of the box. Open them, make holes with the bradawl, and put in -the screws. If you have not a screwdriver, you can turn them with the -end of an old knife; but you may as well get a small screwdriver, for if -you intend to do good work, you will often use screws instead of nails. -Hinges are always screwed on. Now lay the cover in place carefully, mark -its position, so that you have some sort of guide-line to direct you, -and then by laying the cover flat on the bench, and standing the (open) -box on its side, you can screw on the hinges upon the cover. Round all -the edges of the cover as you did the bottom, but keep the edges of the -_box_ square and _sharp_; and so you have now a really well-made little -tool-chest. A little brass hook and eye will do to fasten it, for a lock -is rather difficult for a small boy to put on. - -[Illustration: Fig. 8.] - - - - -CHAPTER II. - - -The method of constructing a simple box has been given in the first -chapter, because so many other articles are made upon exactly similar -principles. The rules laid down comprise two or three essential points, -the neglect of which render the ordinary carpentry of boys so essentially -bad. Foremost of these is _the use of the square_. There is no tool of -more general use in the hands of workmen in wood and metal, and yet, -generally speaking, either none at all, or a very faulty one is added to -the collection of tools ordinarily supplied to boys. In the next place, -I have insisted upon _accuracy in measurement_. The carpenter’s rule is -not at all difficult for a young boy to understand; but even if he is not -in possession of such at his first attempts, he should always be induced -to work by measure of some kind. This causes him of necessity to exercise -his mind as well as his hands, and teaches him to consider well at -starting as to what he must allow for thickness of wood, the difference -between inside and outside measurement, and so forth; all this will -greatly conduce to his success, and consequently satisfaction in his -work, and will lessen the chances of his beginning a number of articles -and casting them aside unfinished—a propensity too common in all boys. - -I shall now resume my directions in the first person, which I think -is the more easy method both for master and pupil. The next specimen -I propose, because it requires even more care than a box, but is at -the same time perfectly within a boy’s powers, is a birdcage. Of these -there are such a number of varieties that it is difficult to settle -upon the best kind to begin upon. I think, however, a wire cage will on -the whole be the easiest to construct, only you must take great care in -boring holes in the thin strips of wood, and, indeed, if you can get a -birdcage-maker’s awl besides the one you have, it will save both time -and trouble. It is not made round with a flat end, but is three-cornered -with a sharp point, so that it has three edges, and when it is carefully -used and twirled round and round by the fingers in making holes, it will -hardly ever split even very thin strips and pieces of wood. However, if -you cannot get one never mind, you must use the common bradawl according -to directions here given. - -I shall suppose you now in possession of a carpenter’s rule, and that you -have carefully learned all I told you of the inches and eighths, so that -you may be able to measure and mark your work very truly. The front of -the cage is represented in Fig. 9, before the projecting roof-boards have -been put on. - -[Illustration: Fig. 9.] - -Here you see two upright strips at the corners, which shall be 8 -inches long. These are 12 inches apart, _outside_ measure. They are ⅜ -(three-eighths) of an inch square, and you must get them ready planed -from the carpenter. There will be four of them required, as they are at -the four corners of the cage; so that, as they are each 8 inches long, -you can get a strip 36 inches in length by three-eighths wide, and this -being 4 inches more than you need, will allow for waste. At the lower -part of the drawing, you see the edge of the bottom board, which projects -a little all round. As the _outside_ of the front pillars are 12 inches -apart, this board may be 13 inches long, which will allow a border of -½ an inch (half an inch), and it may be 8 inches wide. It need not be -_thicker_ than a quarter of an inch. A little above this board (say half -an inch) is another board from one pillar to another, which is to be 1¼ -inches wide and three-eighths of an inch thick. As the pillars are also -three-eighths thick, and their outside edges 12 inches apart, you must -take 6/8 (six-eighths) of an inch from 12 inches to find the length of -this board. - -If you look at the divisions upon your rule, you will see that -six-eighths of an inch amounts to exactly ¾ (three quarters), so that -your board must be 11 inches and _one_ quarter long. This will also be -the length of the board at the top where it falls between the pillars, -and this too must be three-eighths thick. - -I shall now show you how to mark and cut this top piece into the shape -here sketched. Cut the board first of all into an oblong, and mind -that you mark it by your square, so that the _ends shall be square to -the sides_. Let it be 2½ inches wide. Here it is (Fig. 10). Measure a -length of 6 inches from either end to the middle at A, and make a mark -at that place. Draw a line, C B, one inch from the opposite side, the -whole length of the board, and mind you draw it correctly. You should -measure an inch at B, and at C, and then draw a line from one point to -the other along the edge of your rule. You must now draw two lines from -the spot you marked at A to the ends of this line (where you see the -dotted lines). In order to cut this piece, you must begin at A, not at -B or C, or else if the saw should stick you will be sure to split off a -strip right across the piece; but if it should stick when you are cutting -_from_ A, you will only split off a bit of one of the three-cornered -outside pieces, which would not signify at all. - -[Illustration: Fig. 10.] - -When you are sawing, be sure, as I told you before, not to cut into the -line you have marked, but saw just outside it, so that the lines will be -left upon the two sloping sides of the board. You may _cut as close to -it as you can_, but you must not destroy it, and then you can with your -knife neatly shave off the rough edges which the saw has made, until you -have pared the wood quite neatly all along the line. If you cut this line -out, you will no longer have any guide to work by. Cutting out guide -lines is a very common fault, not confined to small boys or big ones. You -will find it easy to pare this sloping side if you begin to work from -A downwards to B and C, but you cannot cut it in the other direction. A -carpenter would, of course, run his plane down the slope, and so will you -by and by; but planing is difficult, and it is better you should wait for -a time before you buy a plane; for, remember, those foolish little things -in boys’ tool-boxes are no use at all. - -You had better now prepare the holes into which the wires are to be put -as you see in the drawing. You can use either iron wire or brass, but -the first is cheapest. These will have to be a quarter of an inch apart. -Both the top and bottom strips, you will remember, are 11¼ (eleven and a -quarter) inches long. Now, 11 inches will be 44 quarters, and one more -will be 45; but as the first hole must be a quarter of an inch from the -ends, you will find that 44 holes will be required. Look at your rule and -count this. You must mark all these by little dots with a pencil on one -piece, and then laying the other upon it, mark the rest exactly even with -the first. Do this with great care, or the wires will not stand upright -when the cage is finished. The space between the top and bottom pieces -will be 5¼ inches, so that if you allow the wires to enter a quarter -of an inch at the top and bottom, you will want 44 wires 5¾ inches in -length—you may say, 6 inches. You can have them all cut and straightened -for you, but if you have a pair of pliers with cutting edges, you can do -it yourself, and it is almost necessary you should get a pair, or borrow -them, if you intend to construct wire birdcages. You will want a few less -in each side of this cage, as it will not be there so wide as it is in -front. We shall presently see how many it will require. - -You may put together the front of the cage at once and set it aside, -or proceed to cut out the rest of it. Generally speaking, it is the -best plan to cut out and prepare all the main parts of your work before -proceeding to fix them in their respective places; but the front of such -a cage as I am describing, being complete in itself, you may do as you -like about it. We will begin with the wires. Insert the ends one after -the other in a row in one of the pieces, laying it upon the bench, or -fixing it on its edge in a vice, but taking care not to bend them. When -one piece is thus stuck full of wires, lay it flat on its side, and put -the other piece in its place, and one by one insert into it the other -ends of the wires. A pair of pliers will help you greatly in doing this. -I daresay the two pieces of wood will not be very parallel, but will be -closer at one end than at the other. This does not matter, because you -will set it right in nailing on the upright strips or corner pillars. -This, therefore, is the next thing you must do; and you must have two -brads top and bottom, each an inch long, but as fine as you can get. Nail -to the top board first, and then place the other in position half an inch -from the bottom of the pillars. If you have no carpenter’s vice, you had -better work with the front of the cage laid down flat and near the right -hand edge of the bench or table, so that the pillar almost overlaps it. -In this position, you can bore the two holes and nail it together; but be -guarded as to splitting the pillars. - -You ought now to have the front well and firmly put together and standing -square and true as in the sketch; only the bottom board, of which you see -the front edge, is not to be attended to at present. - -[Illustration: Fig. 11.] - -There is another way of going to work, namely, to put the whole framework -of the cage together and add the wires afterwards. In this case (the -holes having all been made beforehand as directed here) the wires are in -turn inserted at the top, and then being slightly bent are put in place -in the bottom piece—each wire being completely fixed before the next is -added. Either way may be tried, but in that given above the wires are -not bent at all, and therefore have not to be straightened. Adding them, -however, afterwards is the common practice among the cage-makers. Indeed, -it generally happens in large establishments that one set of workmen -make the woodwork, and another set add the wires—such division of labour -proving more advantageous. - -[Illustration: Fig. 12.] - -Attention is now to be given to the sides, of which Fig. 11 is a drawing. -Here you need not make any corner pillars. You have only to cut out the -top and bottom strips—the lower one, 1¾ inch wide, to match that in -front: the top, 1 inch wide, to match the straight part of the ends of -the upper front piece or gable, as you see in Fig. 12. You will also see -by this drawing that you must nail the side pieces _inside_ the corner -pillars, and _not upon_ them, so that the nails go in from the front of -the cage into the ends of the two side pieces which carry the wires. I -have shown by dots (Fig. 12) where the nail holes are, and they must be -carefully made, avoiding the places where the other two nails come, which -you hammered in when you fitted together the front. The side strips, A B -(Fig. 11), may be 8 inches long. Both sides of the cage are to be made -exactly alike. I have told you to make the lower side-rails 1¾ inch wide, -because they must come to the bottom of the pillars, for no half-inch -space is required at the sides between these rails and the bottom of the -cage. It is so left in the front, because a tray, or cleaning-board, -has to be slid in there. You had certainly better put together the side -pieces by means of the wires, as in Fig. 11, before you nail them in -their places. - -You now require a piece of board for the back, and quarter-inch stuff -will do very well. Bought cages are made of much thinner wood, generally -mahogany, but at first it will be easier for you to use thicker boards. -If you round off the edges, they will not appear so thick. Very thin deal -will warp or bend after it is made up; and, indeed, it is quite possible -the back of this cage will do so. Get the wood, however, as dry as you -can, and the top boards, when nailed on, will probably prevent it. - -To cut out this back board, you may lay down upon the piece from which -it is to be cut the whole front of the cage, and draw a pencil round it, -only, when you come to the bottom of the side pillars, you must draw a -line straight across from one to the other. Then cut _from_ the point at -the top, as you did before. Let the grain of the wood run up and down, -_not across_, the back. Nail the back thus cut to the side strips, as you -nailed on the front, and you will then only have the roof to put on, and -the bottom. - -This roof may consist simply of a thin board, cut square and true, nailed -on to the two gables, and it will look much prettier if it is made to -project beyond the front. If you measure down the slope of the front or -back top-piece, you will find it 6 inches long, and a little more. Your -board should therefore be 7 or 8 inches wide, because, although the roof -pieces meet at the top, they should come down a little beyond the sides -of the cage. As the sides are 8 inches wide, cut the top 11 inches long, -which will allow it to project in front 3 inches. - -If you look at the cage at the end of these directions, you will -understand this. You must slope, or _bevel_ off, the top edges of these -roof boards, to make them fit neatly together along the ridge; and as you -will paint the cage, you can glue on a narrow strip of paper, to make it -quite water-tight. The door of these cages is generally in the back. You -merely mark and cut out a square hole about 3 inches square. You then -fit a piece in, and hinge it either with wire, or (which is easier) by -sticking on a strip of calico down the edge of it, and fasten with a wire -hook. As the back is but a quarter of an inch thick, you will be able to -cut out the hole (before nailing on the back), with a sharp pocket-knife; -and again I say, don’t cut out the guide-lines—cut inside them, and then -neatly pare exactly up to them. Make the bottom 13 inches long, and 10 -wide, which will allow it to project in front, and also half an inch on -each side. - -[Illustration: Fig. 13.] - -You have now to make the tray, to slide into the space left in the front -below the bottom front rail. This is to hold sifted sand, and is made -loose, because it requires to be taken out and cleaned every day (Fig. -13). It is merely a flat thin board (one-eighth of an inch will be quite -thick enough), with a strip nailed on, or glued on, in front, to fit the -space left for it, and other smaller strips glued on all round it, so as -to form a very shallow tray or drawer. The small strips can be glued -on flat _upon_ the top of the board, but to fasten on the front, you -must first glue on a similar strip to those round the sides, and just -such as you made the pillars of, but not quite so thick, and then glue, -or nail on with very small brads, the front piece, nailing or gluing it -to this strip. This will make it very firm, and will do well enough for -your first cage. A, Fig. 13, shows a part of the drawer, C is the front, -and D the strip it is glued to. The handle of this drawer or tray is -to be made of wire, unless you can find some little knob or other that -will do. If you succeed in making this cage, you will have learned a -good deal, because, although not really difficult, it requires care and -consideration; and if you are in a hurry, you will split the wood, or -make it crooked, or cut the pieces too short. It should be neatly painted -in oil-colour—_green_ is a favourite colour—but the top boards may be -red, and the wires should be left clean and bright, because the bird -often pecks at them. If you paint the _inside_ of the woodwork, it should -be white. - -I have not here put any feeding-boxes, or seed-drawers, because glasses -are the best; but you will see two holes (Fig. 11), one inch across, in -the lower side pieces, for the bird to put its head through to get at the -seed and water. A bit of wire, forming half a hoop, supports the glasses -or trays. These ought to be cut with a centrebit—a tool you have not, and -the carpenter had better do it for you. Here is the cage complete (Fig. -14). You can do without making holes in the sides, if you put two wires -longer than the rest, and bend them, as you see at B in Fig. 13, before -putting them in place. - -[Illustration: Fig. 14.] - - - - -CHAPTER III. - - -The previous chapters were devoted to such exceedingly simple and easy -specimens of carpentry as can be made by any boy of eleven or twelve -years of age, or even younger, who has the necessary perseverance, and -will take sufficient care in measuring and fitting. In both and all -similar cases, it is better for such to buy pieces of board already -planed, and of nearly the desired size; but I shall no longer presuppose -such necessity, but advance the young mechanic to the dignity of a plane, -and a few more of the more necessary and useful tools. The list may -therefore now comprise— - - 1 HAND SAW, 16 inches or so in length, a full-sized one being - almost beyond the powers of a boy. - - 3 FIRMER CHISELS, quarter, half, and one inch wide. - - 1 MALLET.—Chisel handles should never be struck with a hammer, - which splits the handles. - - 1 HAMMER.—This should be light. The best way is to buy a - hammer-head, and make the handle. A heavy one can be added, but - will hardly be required at first, and is useless for light work. - - 1 JACK PLANE, 1 SMOOTHING DO.—The jack plane is not usually - added to a boy’s tool-chest, but it is impossible to plane up a - long straight edge without it; and as these planes can be had - from 12 inches in length, I should certainly recommend one, say - 12 to 15 inches. - - 3 GIMLETS, 3 BRADAWLS.—One of each of these should be as small - as can be obtained. Add a medium and a larger one. - - 1 SCREWDRIVER, 1 PINCERS, 1 CUTTING PLIERS.—Screwdriver should - be of a medium size; the pliers such as are used by bellhangers. - - 1 COMPASSES.—These should be light _carpenter’s_ compasses, not - such as are made of brass and steel. They are very useful. - - 2 GOUGES.—_Carpenter’s_ gouges, not turner’s. They will answer - for the present, in many cases, to make round holes in boards. - The centrebits and braces are expensive. - - 1 OIL-STONE.—There is a cheap and quick-cutting stone called - Nova Scotia which will answer the purpose well. - - MORTICE-GAUGE.—The use of this will be shown presently. - - 1 SQUARE, 1 2-FOOT RULE, GLUE POT, and BRUSH.—These are, as - before stated, indispensable. The rule need not have a brass - slide; the square may be made entirely of wood, or with a metal - blade 6 to 9 inches in length. - -The above, with the addition of a carpenter’s brace and bit, two or -three augers, about three mortice chisels, and a hatchet, would suffice -for a very large amount of good work. Indeed, it represents almost a -complete set of tools, the only additional ones that are at all likely -to be needed being a longer (trying) plane, rebate plane, and pair of -match, or tongue and groove planes. Without any of the latter, the young -carpenter will find it easy to carry out a good many light specimens of -his ingenuity. - -It is much better, in general, to work with a few tools, and contrive -to make them answer all sorts of purposes, than to lay in a larger and -more expensive set at starting, for the latter are sure to be abused and -kept in bad order, because if one chisel gets blunt, another is taken up, -instead of sharpening the first; and planes and other tools are treated -in a similar manner, and a carelessness is engendered fatal to success. -It is astonishing how much may be done with few and inefficient tools, -but then the utmost patience and industry have to be exercised, much as -we see prevailing among the native workmen of India and America, who -execute the most beautiful and delicate work with tools which, in the -hands of a European, would be generally simply useless. - -The next work that should be attempted by the young mechanic should be -mortice and tenon jointing, as used in constructing frames of various -kinds for doors, window-sashes, tables, and other articles of everyday -use. Perhaps one of the simplest and easiest examples will be a -towel-horse, which, at any rate, will be of use when completed. - -Now, it may be at once stated, that for work of this kind especially, -but generally also for all work, it is essential to be able to square up -truly the several pieces required. This will require practice—long and -careful practice—and the beginner will meet here with his first and chief -difficulty, but he must not despair. - -[Illustration: Fig. 15.] - -It has been presupposed that a strong work-bench, table-plank mounted -upon trestles, or some sort of tolerably efficient and firm bench has -been obtained, or is accessible, and, in addition, a strong stool upon -which to saw, cut out mortices, and so forth. A small carpenter’s bench, -with a wooden vice, is most handy and serviceable, but is not absolutely -necessary. It will be easy to _make_ one by and by; for the present, any -available substitute must be used. The height of the proposed towel-rail -may equal the length. About 2 feet 6 inches will be a fair size, and it -may be of the simplest possible form, such as is here delineated (Fig. -15). The upright sides may be made of strips of pine, one inch wide and -three-quarters of an inch thick—the rails 1¼ wide and three eighths -of an inch thick. The feet will be considered presently. If careful -attention is given to the following directions, not only will the result -be certainly satisfactory, but the way will be paved for the workmanlike -construction of a great number of similarly useful articles. - -The size of the rough material must always be greater than that -ultimately needed, to allow of the necessary waste in sawing and planing. -Pine boards, however, are usually cut of certain general widths and -thicknesses; and although we have here set down stuff of _one inch_ by -three-quarters, it may be cut from inch board, because very little will -be wasted by the plane, and the finished work will be sufficiently near -to the above measure for the intended purpose, one-sixteenth of an inch -or so being of no practical importance in the construction of such an -article as a towel-rail. Get, therefore, from the carpenter, a strip of -pine 1 inch wide and 6 feet in length, cut from a board 1 inch thick, -and also a strip for the rails (of which there will be three), 4 inches -wide and 2 feet 9 inches long, cut from a half-inch board. The rails you -are to saw yourself from the latter strip, which will give you practice -in sawing a straight course, and the _work_ is easy in half-inch stuff. -You may therefore begin by cutting these, for which purpose you will want -guide-lines dividing the strip into three of equal width. There is a very -simple way of marking these by means of a chalk line, which I will here -describe. - -The width of the board I set down at 4 inches, because the rails, when -finished, will be 1¼ inches each, or, in all, 3¾ inches. As each contains -eight eighths, as already explained, 4 inches will contain thirty-two -eighths. Dividing by 3, we shall have ten eighths for each strip, or 1¼ -inches, and two eighths, or a quarter of an inch, to spare for waste. -Take the compasses, therefore, and open them to 1¼ and a little over -(rather less than to the next division on the rule), and take it off at -each end of the board (Fig 16, A B). - -[Illustration: Fig. 16.] - -Take off, again, from this to mark the width of the next strip, and the -board will be divided with sufficient accuracy for our present purpose. -Take a piece of twine, long enough to stretch from end to end of the -plank, and something over, and tie a knot at one end. Stick a bradawl -through the string, close to this knot and into the board, as seen at C -of the same figure. Take a lump of chalk, and chalk the line from end to -end. Then strain it down the board, holding it by the left hand, so that -it is stretched from one mark to the other, where the saw-cut is to be -made. With the finger and thumb of the other hand, raise it a little in -the middle, and let it suddenly go, when it will make a perfectly clear -and straight line upon the board. Make a similar and parallel line for -the next saw-cut. In the present case, you need not mind cutting this -chalk mark out. Try and saw right down, so as to split it. - -[Illustration: Fig. 17.] - -You now have your strips cut out, but they require to be planed. You -might, indeed, with advantage, have planed the whole strip on both -sides before marking and cutting it, but it is equally easy to do it -afterwards. The jack plane is the one to be used for this purpose. I must -suppose it to be sharp and in good order; if not, ask some carpenter to -set it for you for the present, but I will soon tell you how to do it -for yourself. Indeed, you will have to learn how to sharpen all your -tools before you can be called a good workman. If the plane is properly -set, the cutting edge will project very slightly only from the bottom; so -that when held as in Fig. 17, and the eye directed along the sole, only a -narrow shining slip of metal will appear. If too far out, it will hitch -and make bad work; if not far enough, it will not cut at all; but the -common fault of beginners is to have it too far out, because from their -imperfect handling of this tool they often fail to make it cut, when in -the hands of a carpenter it would work well. Now, if the iron projects -too far, hold it as shown, so that you look along the sole, and give it a -tap with your wooden mallet on the upper face at A, and this is also the -way to loosen the wedge and irons for removal. By a blow at B, you can -send the cutting edge forward to cut more deeply, or in this case you may -tap the iron itself with a metal hammer, but tapping the end of the wood -is better. - -To plane the edges of these strips, you ought to have a bench with a -vice, but there are ways and means to do without it, and one is so good -that I shall speak of it here, although it necessitates a somewhat abrupt -break-off in my description of the towel-rail. It is a kind of vice that -is fixed to a board which is laid upon the work-bench when required. - -[Illustration: Fig. 18.] - -In Fig. 18 is a drawing of one of two kinds of such vices which I will -explain. This first consists of two pieces of wood (ash will be better -than pine) about 9 inches long and 2 inches thick. They are cut in the -shape given in the drawing, and screwed to the board, not tightly, but so -as to move freely upon the screws. The board should be an inch thick to -give the screws a firm hold. You can see by the figure that the tails of -the pieces cross each other sometimes when in use. To allow of this, they -are cut like B and C, so that one can go inside the other. Now, if you -consider a little, you will understand that if we stand a strip of board -between the two, and push it forward against the insides of the tails of -these curiously-shaped blocks, it will make the opposite knobbed ends -close nearer together, and these will grip the piece of wood, and the -harder we push it forward, the more closely it will be gripped and held; -but the moment we draw back the piece, the two jaws will open to let it -go free. You can try first of all upon a thin piece, which can be shaped -by your knife, and make a model of this vice, and then if you can’t -manage to cut out such a one of thick wood, the carpenter would do it for -you, and it will be handy for many purposes. If you have nothing of this -kind, nor a vice to your bench, drive in two pins or pegs of wood, or two -nails, a little way apart, so as to allow your strip of wood to stand -upon edge between them, and drive two more a little way from these; then -one at the end to form a planing stop. A tap at the sides of these nails -will cause them to hold the strip edgewise, quite well enough to allow -you to plane it. There are other ways, and I shall describe them by and -by. In the meantime use nails, or any other plan that will answer. - -[Illustration: Fig. 19.] - -[Illustration: Fig. 20.] - -I shall suppose, therefore, that one of the narrow strips is thus set on -edge upon your bench ready to be planed. Grasp the handle of your plane -firmly with the right hand, and lay hold of it in front of the iron with -the left. Draw it back, and then send it steadily forward, pressing it -downwards at the same time. Now the advantage of a long plane is, that -it does not descend into the hollows of the work, but rests upon the -projections, as in Fig. 19, A. A short plane would do as seen at B, and -therefore would never make a long straight edge. You have two special -points here to attend to. You have to plane a level line from end to end, -and also keep the edges square to the sides, which is by no means easy -at first. You must keep trying it with your square, as I have shown you -in Fig. 20, and not rest satisfied until the handle fits close to the -side of the strip, and the edge lies also close upon that of the strip -anywhere along its length. I daresay you will think this of no importance -in such a common thing as a pine towel-horse; but I may tell you this -is the very secret of carpenter’s work, and when you can saw and plane -truly, and work “to square,” you can make almost anything. It is true -that the strips for the rails are not of great importance in this case, -but the upright side pieces are, and if these are out of truth, the holes -cut through them for the rails, which are called mortices, will be out -of truth also, and you will see the towel-horse, when it is made, all -twisted and awry, and nothing you can do will make it stand firm or look -well. It is, in short, no use to pretend to learn carpentry unless you -at once make up your mind to succeed, and therefore you must always use -the square and try your work as you go on. All the difference between the -usual work of carpenters, and that of boys or men who do not know how to -work, consists of the squareness and good fit of what the former make. -Boys never seem to trouble themselves about such things, and so you see -their boxes and rabbit-hutches look twisted, and being badly fitted, they -soon go to pieces. - -Having planed up the sides and edges of the rails as square and true -as you can, cut the other long strip in half, and square up this also, -taking care that both pieces are alike and both truly worked. If your -bench is sufficiently long to take the whole strip, plane it up before -you cut it across, and you will be sure to have the sides of your -towel-rail equal in size. You have now to make your first essay in -cutting mortices. Follow these directions, and you will not fail. I shall -not limit the description to these special mortices, but give you general -directions. - -[Illustration: Fig. 21.] - -Fig. 21 represents a bar of wood—the side of the towel-horse, for -instance—with a mortice cut through it at A, and others marked out at -_ab_, _cd_. Below, at B, is a gauge, of which the construction and use -will be explained presently. F shows how the feet are to be attached and -cut. They are morticed while in a “squared-up” condition, and shaped -afterwards according to fancy; sometimes they are left square, and knobs -screwed below to make two feet. - -These mortices may, of course, be of any desired length or width. Those -required for the towel-rail sides will be 1¼ inch long by half an inch -wide _nearly_. The planing of the strips may have reduced them more or -less below the exact size specified, try therefore with the compasses -what the precise thickness is of the ends, and measure that thickness on -your two-foot rule. You now want to draw the lines _a t_, which I have -represented as extending the whole length of the strip, and as all the -mortices are to be alike, you may so mark them. The gauge B is of two -parts, a sliding piece, C, and a rectangular bar of wood about 9 inches -long and half an inch square. This slides stiffly through the mortice -in C, and is fixed at any part by the small wedge D. This gauge you can -easily make. It is _not_ a mortice gauge properly so called, because the -latter has two marking points instead of the one seen at _h_, and which -may be the point of a brad driven in and filed up to an edge. Loosen the -wedge slightly, and draw back the rectangular bar, or push it forward, -until you think that the space between the sliding piece and the point is -about that which is required on each side of the mortices, so that if you -set the wedge firm, and resting the sliding piece against the edge of the -board, cause the point to make a mark, and repeat this on the other side -of the same face of the wood, there will be left between the marks thus -made the exact width of the required mortice. Try it, and if not, give a -tap to the instrument, and adjust it until the space is exactly correct. -Then fix all firm, and holding it so that the little point will mark the -wood, while the head or sliding piece is against the side of the board, -run the tool from end to end, or run it along just where the mortices -are required, using both hands. You will thus make the two long lines -between which the mortices have to be cut. Now turn the wood over, and -do the same on the other side. You are now quite sure that these lines, -on opposite sides of the piece, agree exactly in position, which is the -object of using a gauge; and as you have planed up a second strip to -exactly the size of this first, you have but to repeat the process (no -measuring being necessary) upon that; and you may be satisfied that thus -far the two sides of the towel-rail will tally. You now set off with the -compasses upon one of these lines the _lengths_ of the mortices in their -proper places, and at the points thus marked, using your square for the -purpose, mark the end lines of these mortices; but when so doing, carry -the lines across, as _a b_, _c d_, and down the sides and across the -opposite side. With the square this will be easily done, the blade of it -being laid _flat_, so that its edge becomes the ruler, while the handle -becomes the guide or gauge resting against the side of the wood. At E, -Fig. 21, this position of the square is shown. - -By thus carrying round all the lines, you will have the mortices marked -on both sides in exactly the same relative position, so that you can -(and must) cut them half from one side and half from the other, using -the chisel nearest to the size required, but _always of less width_ (or -length) than the mortice, because _you must never cut out the guide -lines_, but must keep within them, only carefully paring the wood at -last close to them. You will never cut mortices correctly, unless you -thus mark the position on both sides, and work as directed. - -The ends of the cross rails will not have to be cut into tenons, as they -will fit as they are, only requiring to be glued into their places, -when, if you have worked carefully, the whole will look well, and will -be square and true, without twist; but if you did not plane up the sides -square, you will find the towel-rail awry and unworkmanlike. Although, -however, there is no necessity to make regular tenons in the present -case, the usual way is to do so, and to fix with wedges, as in Fig. 15. -After a mortice has been cut straight through a piece as directed, this -mortice is slightly eased, or sloped off, as seen at _a b_, which is a -section of one. The rail or tenon _c_ is put through after being brushed -with glue; and when in exact position, two wedges are glued and driven in -at each end, as seen in the drawing. After all is dry, these wedges being -firmly united to the rail, as seen at _k_, prevent it from being drawn -back or moved. Nearly all mortice and tenon joints are fixed in this way. - -As I am describing this kind of work, I may as well explain the method of -marking and cutting tenons, as it will answer not only for affixing the -feet, as shown in Fig. 21, but for all similar work. - -[Illustration: Fig. 22.] - -In Fig. 22, I have illustrated the mode of marking out tenons, and at -D is a double tenon, which is in wide pieces often substituted for the -single, and makes an excellent joint. The longitudinal lines _e_, _f_, -_g_, _h_, are marked as before with the gauge, whether for single or -double tenons; the line _a b_, with the assistance of the square; the -cheeks, _c_ and _d_, are then cut off entirely with a fine saw, called on -this account a tenon-saw,—and care must be taken as before not to cut out -the guide lines. If, instead of the outer cheeks, the piece between them -is to be removed to make a double tenon, this must be done with mallet -and chisel, after carefully sawing down the lines _x y_; and the chisel -is to be used first on one side and then on the other, by which means -the shoulder will be cut true to the guide lines. If, however, the cut -across should curve a little downwards like _n_, it will not much matter, -so long as the _edges_ fit closely. It is nevertheless better to cut -straight across. The outer cheeks of this will be marked and cut as in -the single mortice (Fig. 22). - -If a workman has to cut many mortices on pieces of the same size, he -frequently constructs a rough mortice gauge with double points, which -marks both sides of the mortice at once, like K. A fixed block at K, -the right distance from the points, _l m_, of two nails, is sufficient -when all the mortices are to be alike. There is, however, a regular -double-pointed gauge, made generally of ebony, plated with brass, and a -brass rule to which one of the points is fixed, and which is acted on by -a screw at the end, which can be turned by the thumb and finger. This -has the effect of separating or closing the two points according to the -desired width of the mortice, its distance from the side of the piece -being regulated as before by the sliding head fixed by a wedge. This is -an expensive tool, and need not be purchased. There are also, let me add, -many costly tools of various forms and uses; but let the boy’s motto (and -man’s, too, for all that) be, “_Do as well as you can without_.” You have -no idea how a little ingenuity and contrivance will save your pockets, -and that, too, without in the least tending to spoil your work. All -you require are a few of the most generally useful tools in first-rate -condition—chisels, saws, and planes, sharp and well set, and fit for work -at any moment. - -With regard to uniting two pieces of wood or other material with glue, -it must be remembered that if you use this substance in a thick semifluid -state, and in quantity, its effect will be lost. Make it a rule to put on -as thin a coat as possible, and let it be not thicker than cream, so that -it will freely flow into corners, and spread evenly over the surfaces to -be united. Make the wood also _quite warm_, so that the glue shall not be -suddenly chilled, and let it be used boiling. Always heat it either in a -proper glue-pot, or at any rate, place the vessel which contains it (a -small gallipot, for instance) inside another vessel in which water can be -kept boiling. - -The glue, which should be thin and transparent, being broken into small -pieces, should be put into such a vessel as suggested, and covered -with cold water, and it should be allowed to remain thus until swollen -and softened. Then bring the water in the outer vessel to the boiling -point, and do not use the glue until it is entirely dissolved and of one -uniform consistence. It should be stirred while boiling with a piece of -stick, and a brush used to lay it upon the pieces to be joined. It very -generally happens that pieces glued by boys fall apart almost directly. -This is almost entirely due to the fact that the glue is used thick and -clotty, and in too great quantity, while the wood is never made warm -as it should be. If two pieces are properly joined in this way, it is -almost impossible to separate them at the joint—the wood itself will give -way and split before the glue will yield to the strain. Carpenters use -various forms of clamps or vices to hold work together until the glue -shall be dry; but for boys by far the best plan, where any such holdfast -is needed, is to bind the parts together with twine, and then to set them -aside for twelve hours at least. It is seldom that articles once united -by glue and separated will unite firmly a second time. - - - - -CHAPTER IV. - - -The exercise of a boy’s mechanical tastes upon works of practical utility -is, of course, far preferable to its expenditure upon mere trifles, -made one day to be cast aside and destroyed the next; and as there is -scarcely any household that does not need its furniture repaired or added -to from time to time, I shall now give directions for the construction -of one or two articles that seem to be within fair scope of a young -mechanic’s abilities. The first is a plain, useful table, without a -drawer, and with square legs, because without a lathe the latter cannot -be made ornamental; and lathe work will occupy some future pages, since -it is necessary first to give the young mechanic a fair insight into the -principles and practice of plain carpentry and joinery. - -The _very_ young mechanic, so far as my experience of him goes (and it is -rather extensive), makes his early attempt by sticking the points of four -nails into the corners of any tolerably square piece of board he can lay -hands on. His next attempt, when he has risen to the dignity of a knife -and gimlet, is to place four _wooden_ legs at the corners of a similar -board, which, if the said legs are _glued_ in (by which a wonderful mess -is always made of the structure), is considered a great feat, and worthy -of the admiring patronage of fond parents and playmates. Now, a table -does not consist of any such arrangement of pieces, although I certainly -have seen sometimes, in the cottages of the poor, a three-legged -affair of this nature, which is just nothing more than a magnified -milking-stool. We cannot content ourselves now with anything of the kind. -We shall have to work away with plane and chisel and square, and with -neat tenon and mortice joints first construct the frame upon which the -top will be placed, and then finish it _secundum artem_, the English of -which, as I am writing to boys, I shall not reveal. - -The table shall be 3 feet long, 1 foot 8 inches wide, 2 feet 4 inches -high; the top board being half an inch thick when planed and fitted, for -which it will therefore be required to be three-quarters of an inch in -the rough. The legs demand attention first. Plane up strips cut from a -2-inch board, and let them be exactly 2 inches wide. These must be worked -up with the greatest possible accuracy, or it will be impossible to fit -the framework so as to make the table stand truly or bear inspection. -After four such strips have been planed up, cut a piece from a half-inch -board, or from a board that will plane to half an inch. Let this be 4 -inches wide and 9 feet long, and be sure to plane this also truly, and to -make the edges square to the sides. - -[Illustration: Fig. 23.] - -If you have no strip that will answer of 9 feet long, you can cut two or -more instead, remembering that you will require two pieces each 18 inches -long and two of 2 feet 9 at the least, all as nearly alike in _width_ as -possible. You have now all that you will need for the framework of your -table—the top may be left till the rest is fitted. Now you may proceed -to cut the requisite mortices in the legs, which you will understand by -sketch Fig. 23, which represents one corner of the table before the top -is added. There is no more difficulty in this than in the previous work, -except perhaps that somewhat more care is requisite in squaring up the -several pieces and cutting the mortices with accuracy. Use the gauge as -before in marking the mortices, trying it until it is so fixed that it -will leave the proper width of the holes, namely, half an inch (which is -the thickness of the strips which are to form the framework). This is -upon the supposition that your gauge has but one marking point: but to -explain its use. - -[Illustration: Fig. 24.] - -I shall now introduce to your notice a regular mortice-gauge of two -points, which is vastly more convenient. This is represented in Fig. 24. -The main stem is grooved along its length on one side with a dovetailed -slit, that is, a groove which is wider below than above. This is -generally made in a brass plate attached to the stem of the gauge, but -sometimes in the wood itself. In this slides a slip of brass which can be -drawn back by pulling the knob A, or by turning a thumbscrew at one end, -as in the more expensive gauges. One of the marking points is fixed in -the end of this slide, the other in the wood (or metal) beyond it, at -B, and when these are allowed to be together they form but one point, -being flattened on one side, so that they will fit accurately against -each other. Thus it is easy to separate the two points at pleasure to the -exact width of the required mortice. By means of the wedged sliding piece -C, we now have merely to determine how far the edge of the mortice is to -be from _one side of the piece_. Thus, suppose that in the present case -we should prefer to have the side of the frame nearer to the outside edge -of the legs than to the inside, we can so arrange it easily; but we must -then take care to gauge all alike, either from the inside edge or the -outside. We do not, therefore, with this kind of gauge work from _both_ -edges, and leave the space _between_ the lines for the width of the -mortice, but we work from _one_ edge only of the piece of wood, and mark -the mortice at once in any desired position. I need hardly repeat, that -for any particular job, a very good substitute for such gauge can be made -by driving two small nails into a strip of wood cut with a projecting -piece to serve instead of the movable head. - -[Illustration: Fig. 25.] - -Let us now proceed with the work in hand. One of the legs of the table, -before being worked into shape, is shown in Fig. 25; the dotted lines -show how it will be eventually sloped off below the mortices which carry -the top frame. These mortices must not now go through the legs, and -therefore you will have to be very careful to hold the chisel upright, -so as to insure the _squareness_ of the frame when put together. The -mortices being in adjacent sides, will of course meet, but it will be -advantageous to cut those which are intended to receive the two longest -strips, viz., the front and back, rather deeper than the other two. -First set off an inch from the top of the leg at the line A B. If less -than this intervenes between the top of the mortice and the end of the -leg, you will probably break the piece out and spoil your work. As the -side boards are 4 inches wide, and must come flush with the top of the -legs, you will have to cut them like C, and there will be 3 inches left -for the tenon, all of which may be left, as the wider this is the more -hold it will have on the legs into which it is to be glued. It is plain, -therefore, that the mortice will be 3 inches long and half an inch wide; -and when you have marked it to this size, take care to cut it accurately, -because if it is too small, you will break out the piece between the -mortices when you try to force in the frame pieces, and if too large, -you will scarcely get the whole to remain secure. Work therefore exactly -to gauge. It is usual to keep these side and end pieces more to the -outside of the legs than the inside, as F, where you are supposed to be -looking at the _inside_ corner; and if you look at D (which shows the -top or cross section of a leg, as if after the pieces were fitted you -had sawn off the leg close down to the mortices, exposing them to view), -you will see that by thus keeping near the outside edges you get _both_ -mortices deeper than if you cut them, like E, in the middle of the sides -of the leg. Of course, the deeper these tenons are let into the legs, the -stronger their hold will be. There will now only remain to warm all the -pieces and glue them into their respective places, with the precautions -before stated as to the thinness of the glue and speed of the operation. -See that all stands square and true; if not, a tap here and there as -required will set it straight, and then let all stand till dry. - -I have told you to cut the side and end pieces 18 inches and 2 feet 9 -respectively, so that if the mortices are 1½ inches or so deep, your -frame will be about 1 foot 6 inches wide, and 2 feet 6 inches long. The -top, which is to overlap as usual, will be now prepared as follows. -It will not be possible to make this of a single width of board; and -nothing will more fully test the young workman’s skill, than planing the -edges of two pieces so that they shall fit accurately together. It must, -nevertheless, be attempted. - -Cut two pieces of three-quarter-inch board, and plane the sides as -accurately as possible. Then set them up edgewise, either singly or -together, and plane the edges with steady, long strokes of the longest -plane you have, set fine—that is, with the cutting edge projecting but -slightly. Try each singly with the square from end to end, and then lay -them on any perfectly flat surface, as on your bench, or on a table, and -see whether the edges lie close all along. Remember, too, that they may -do so when one surface is upwards, and not when turned over, as will -occur when the edges are not square to the sides. In cutting out the -pieces, therefore,—which, when finished, are to be together 1 foot 8 -inches,—you should make them 1 foot 9, so as to allow you a whole inch -to waste in planing and fitting. When both are as true as you can get -them, lay them down near together, and brush the edges with boiling hot -glue. Then immediately put them together, and rub them a few seconds one -against the other, till they seem to stick slightly. Then leave them in -their exact position, and drive a couple of nails into the bench against -the outside edges, so as to keep them together, or in any other way wedge -them tightly in position until they are quite dry. When the glue is hard -which has been squeezed out along the joint, you may run a plane all over -the united boards, and you ought hardly to see the joint, which will be -nearly as strong as any other part. - -This top has now to be attached to the frame, as follows. Cut some pieces -like K in Fig. 25, and glue them here and there along the inside edges -of the frame, so that one side of them shall come quite flush with the -upper edge. To these the top has to be glued. Lay it, therefore, with its -under side upwards, upon the floor (I suppose the short pieces glued and -_dry_ on the frame), and having also glued the sides of the short pieces -which will touch the under side of the table top, turn the whole upside -down, with its legs in the air, adjusting it quickly. Its own weight will -keep it in position until dry; or, if not, it is easy to lay an odd board -or two across, and put some weights upon them. When dry, turn over your -table, and plane round the edges where necessary; and, if it does not -stand very well, trim the bottoms of the legs. Clean off glue, and rub -any rough places with sandpaper or glasscloth, filling up any accidental -holes with putty, after which it will be fit for receiving paint or -stain, if it is not considered desirable to leave it white. The corners -and edges of the top may be rounded off, to give a finished appearance. - -I showed by dotted lines the usual shape of the squared legs. They are -planed off, tapering from below the frame, and this should be done after -the mortices are cut, and before fitting the parts together. The best -way to insure equal taper of all the legs, is to prick off at the bottom -of each equal widths from the corners or edges, and to run a pencil line -from the point where the taper is to begin to these marks. Then plane -exactly to the lines thus made. - -[Illustration: Fig. 26.] - -Let us now consider what errors of construction are most likely to occur -in working out these directions. First, it is possible that the framework -may be out of square. This may proceed from two causes. In the first -place, the side or end pieces may not be of equal length between the -legs, owing to some one or two being driven further into their mortices -than the others. To avoid this, which is not uncommon in many works of a -similar nature, it is well always to mark the length that each is to be, -irrespective of the part within the mortices, as Fig. 26, A and B. If the -space on each between the dotted lines (_carefully marked by means of a -square_) is equal, it is no matter whether C and D are also equal. We -have only to take care to let them into the mortices to a greater or less -depth, until the line comes exactly even with the inside edge of the -legs. Again, it is possible that when the table is placed upon its legs, -these may not rest truly on the floor. Probably one or two of the frame -pieces run up like E, instead of standing at right angles to the legs. -This results from the mortice not being cut correctly; and as you cannot, -in this case, mark both sides and cut from both, as you did in making -the towel-horse, this is not unlikely to happen. It will not, therefore, -signify much if you purposely cut your mortices a little too _long_, -and then, when you have placed the table on its legs, after gluing up -the frame, and before it is dry, you can force it to stand truly, and -then wedge up with glued wedges where necessary. You cannot, however, -do this with the _sides_ of your mortices, because you require these to -fit exactly; you must therefore use extra care in keeping these as true -as possible. In many cases you can wedge the _ends_ of tenons to correct -a bad fit, but never the sides. These are the probable, or I will say -_possible_, faults against which to be on your guard. - -[Illustration: Fig. 27.] - -In making a similar table with a drawer, the same operations have to be -gone through, but the upper frame is somewhat differently constructed, -and the corners of the drawer are united with dovetails. Plane up the -legs as before, but cut mortices as at A. Fig. 27, which represents the -right-hand hinder leg as you would see it standing in front of the table, -and before the framework had been fitted in its place. B is the other -hind leg, with the tenoned strips just ready to be driven in. The piece -E is made as before, as is also C and its opposite piece at the _ends_ -of the table. But this pair of mortices, you see, are made shorter than -before, and the strip C is notched at the bottom as well as at the top, -forming a regular _tenon_, as it is called. Below this first is a second -mortice, cut the other way, the longest side standing _across_ the leg -to receive a strip, D, upon which afterwards another strip, X, will be -nailed or glued, forming the rebate in which the drawer will slide, and -of which the upper surface must be level with that of the strip M. There -is a plane for cutting out rebates without the necessity of adding a -strip, but I do not suppose you as yet to have such a one. When these -pieces, C and D, are driven up close into their places, they will touch -along their sides, so that on the outside they will appear as one piece. -Of course there will be a similar pair on the right-hand side of the -table. D ought to be tenoned, so that the side on which X is to be nailed -will lie flush or level with the corner of the leg, so that the strip X -shall project wholly beyond it. - -The left-hand _front_ leg is shown at P, with its mortices, and the -tenoned strips between which the front of the drawer will lie, closely -fitting when shut. These front strips should be each 2 inches wide, the -mortices 1 inch long, or as long as you can safely cut them; you must -tenon the cross pieces, of course, to fit these. - -All the rails may be of half-inch board. Mark all tenons across with the -square as before, so as to give the exact _inside_ dimensions, and you -cannot well go wrong. These lines, too, will guide you in keeping the -framework square and true; for if you have planed the legs correctly, and -your strips are inserted exactly to the aforesaid lines, it stands to -reason the work will be satisfactory. To make the drawer, observe, first, -that it is not like a box as most boys would make it, for when turned -upside down, as in Fig. 28, Fig. B, you will find the sides projecting -beyond the bottom, which projections rest in the rebate, X, of the last -figure, and take the whole weight of the drawer, enabling it to slide -easily and smoothly in and out, especially if those surfaces which are in -contact are rubbed with soap or blacklead, or a mixture of the two. At C -you have a drawing of the same, with the bottom removed. This, you see, -is a square or oblong frame dovetailed together, and when it is glued and -dry, the bottom is slid in along the grooves in the sides (one of which -is seen at _x x_), and a couple of brads driven through it into the back -rail, K, fixes it completely. The front board of the drawer is cut and -planed to fit exactly between the two rails which were morticed into the -legs, as shown in the last fig., and is always of thicker stuff than the -sides or bottom. It may, in the present case, be half-inch, and the rest -quarter-inch. - -[Illustration: Fig. 28.] - -If you look at C, you will observe that the front and sides of the drawer -are of the same depth, and that only the back is narrower. (Remember that -in this cut the drawer is seen from below, the groove _x x_ being near -the bottom of the sides, and level with the bottom of the back.) - -To cut dovetails is not difficult, but requires neatness and care—a fine -saw (dovetail or light tenon-saw) and a really sharp chisel; and, above -all things, remember not to cut out the lines which have been drawn -as guides. H is the _end_ of the front of the drawer; L the left side. -Having cut out the latter, and planed it up nicely, draw a line, by the -aid of the square, one quarter or three eighths of an inch from the end -_across_ it. This will be the line _o p_ of the bottom of the dovetails. -Then mark and cut out two or three, as seen in the drawing, using the saw -where you are able, and clearing out with the chisel in other places. -From _o p_, measure the exact _inside_ width of your drawer, and beyond -the second line made across at that distance, leave a quarter of an inch -for the second dovetails, and cut them out as you did the first. Now, -prepare a second precisely similar piece for the opposite side. Next -lay L in place upon H very truly, and with a fine-pointed hard pencil, -or a scriber (a sharp-pointed steel marker), trace round the dovetails, -marking them on the end of H, and with a sharp chisel cut them in a -quarter of an inch deep, which will allow them to take the side piece -exactly flush and level. Mark these two which have been so fitted, and -proceed to do the same at the other end of the front piece, tracing -these, as before, from the dovetails of the opposite side, which are -to be there inserted. You do exactly the same with the back piece; but -as this is both narrower and thinner, the dovetails will be cut quite -through it, and will be seen on both pieces after being glued up, and -there will only be room for one dovetail, instead of two. When all are -cut, lay the pieces in position, glue quickly, press all together, and -contrive to wedge up or bind round the whole until dry, testing with the -square and adjusting, as maybe necessary. We shall return to dovetailing -again, but these not requiring _excessive_ neatness, will be a good -beginning, and show you in what special points care is needed in such -work. Nothing remains but to plane a piece for the bottom, and slide it -into place. - - - - -CHAPTER V. - - -In the last chapter we entered a little upon the matter of dovetails, but -as the mode of uniting the angles of boxes, drawers, and such like, is -of almost universal application, it will be as well to devote a separate -short chapter to the subject. - -There are several different kinds of dovetails used, according as it may -be desired to let them appear upon the finished work, or wholly or in -part to conceal them. Carpenters generally use the kind which is visible -on both sides, cabinetmakers, as a rule, take special pains to conceal -it, only using the other form upon work that is to be afterwards covered -with veneer (a thin covering of some ornamental and more expensive wood -glued upon the surface of that which is of less value, and of which the -article is made). - -The dovetail described in the last chapter, as proper for the attachment -of the sides to the front of a drawer, is not that which is ordinarily -used by the carpenters, but the following, which is somewhat more easy -to make, and is the same as would be used for the other corners of such a -common drawer as that described. - -I must at the outset remind my young readers once again of the standard -rule, without due attention to which they have _no hope of success_ in -this neat and delicate operation of carpentry. _Never cut out your guide -lines, but leave them upon your work_, and use your square diligently -upon the _edges_ of your work, the bottom of the dovetails, sides of the -same, and upon the sides of the pins. Never mind the _time_ necessary for -this. You are doing work, remember, that is to bear inspection,—work that -will stand wear, and be really useful in the household to which you have -the honour to belong. You would not therefore like to see open spaces -here and there, requiring to be filled up with putty, or the side of the -box not truly square to the back and front. And it may be noted here, -that if dovetails are properly fitted together, the box or other article -will stand firm, even before the glue is added; but if the same are badly -cut, and put together carelessly, no amount of glue will avail to hold -the work securely; and it would have been as well or better never to -have attempted dovetailing, as such bad work would be stronger united by -nails, and in any case is but a disgrace to the young amateur mechanic, -whose motto should always be, “_Whatever is worth doing at all is worth -doing well_.” - -[Illustration: Fig. 29.] - -You will remember how you were taught to wedge up mortice and tenon -joints with glued wedges, which, becoming part of the tenon, and -rendering it larger below than above, prevents it from being withdrawn -from the mortice. Now, a single dovetail has the same effect, and is in -point of fact of the same shape and size as the tenon with its wedges -attached. See Fig. 29, A and B, the first being a wedged tenon, the -second a dovetail. - -We shall begin with a single dovetail, which is applied to the -construction of presses used by bookbinders and others, and also -domestically for house-linen. In these there is a strong tendency to -draw the sides upwards, and to tear them from the bottom—a strain which -this form of joint is exactly calculated to withstand. The same is also -used in making many kinds of frames, where similar strength in one -direction is necessary. If you have no special need of such at present, -you should nevertheless make one or two for practice, and to give you a -better insight into their construction. Indeed, if you cannot make single -dovetails well, you will hardly succeed in making a whole row of them -exactly alike, for joining together other articles, as drawers, boxes, -and cabinets. C of this fig. represents a bar of wood truly squared up, -and ready for being marked out. The square is laid across it as seen, -and a line drawn on each side by its assistance, as far from one end as -is the thickness of the other piece to which it is to be attached, and a -little over (say one-eighth of an inch) which will afterwards be neatly -planed off. This is allowed merely because the extreme angles at _e e_ -sometimes get damaged in cutting out the dovetail, and if they are, they -will have to be removed. Having drawn the above line all round the piece, -divide it into three by the aid of your compasses, as shown, on what we -may call the front and back, and then on both these sides draw lines, _e -e_, to the angle. You now have the dovetail, or rather the pin of the -dovetail, marked, and with a fine saw you have only to cut out this piece -as you see at D, taking great care to cut accurately close to the lines, -but to leave them, nevertheless, on the edge of the piece you are about -to use. - -If you can saw truly, you should not have to touch these pieces with a -chisel, but if not, you must take a _very sharp_ one, and pare the wood -exactly true to the lines which you have marked. Now the dovetail made -by dividing the width of the stuff into three, as given here, will not -answer so well for pine, which is liable to split off in the line H H -of the fig. D; but for ash, beech, elm, and such like, it is a good -proportion. If the material, therefore, is pine, divide it into four -instead of three, as seen at E, and draw lines to the angles from the two -outer marks; or, without any such division, set out equal distances from -each side, so as to give about this proportion to the pieces which are to -be cut out. - -Where there are a row of dovetails to be made (as in cabinet work), even -this latter measurement into four would make them too angular, as you -will learn presently. You must now fix upright in your vice the piece -in which is to be cut the dovetail to receive this pin; and laying the -latter in place as it will be when the frame or other work is put -together, draw round it with a sharp pencil or scriber, as seen on the -end of K (the lines _c d_, at such distance from the end of the piece as -is the _thickness_ of the pin, and the perpendiculars, _a b_, are to be -drawn with the square); and if the angles of such pin do not reach the -angles of that in which the dovetail is to be cut, as will often be the -case, the lines on the opposite side similar to _a b_ must be also drawn -with the square. So you see that I was quite right in directing you to -add a square to your box of tools, even before many other requisites of -carpentry. - -If it is not considered desirable that the dovetail should reach the -extreme angles of the pieces, as _a b_, fig. K, the pin piece is first -marked as if for an ordinary tenon, and the dovetailed pin marked on -this, as M. When the fellow-piece is cut out, it will then appear as N. -The effect will be the same as the last, except that the end of the pin -will be more conspicuous. A great deal depends upon the material, and on -the intended use of the finished article, therefore you must use your own -judgment, or consult that of others better acquainted with the art than -yourself. L shows the dovetailed joint complete as last described. - -[Illustration: Fig. 30.] - -We now recur to the row of dovetails and pins—or dovetails and _sockets_, -as the part is often called which is to receive the pins. The most common -kind is that represented by A B, Fig. 30; and as you ought now to be -thinking of a larger tool-box, and would not like it roughly nailed -together like the first, you might try your skill by constructing one -more worthy of the name, and with a drawer or two in it. You must begin, -as before, by marking the two lines across your work by the edge of the -square, or, if you prefer it, by your gauge, which, when set to the -thickness of one piece, will mark the others correctly; and remember to -mark _both sides_. Then set out your dovetails, but do not make them so -angular as you did the single one; for remember you have a whole row of -them to assist in holding the work together, and when glued, this will be -of necessity a very strong and reliable joint, if well made. - -Always make the pins before the sockets, and mark round them as closely -as possible, and take great care when sawing not to break them, and if -possible keep their angles also very sharp and clean. It is solely care -in these particulars, and accurate cutting just to the gauge lines and -no further, that makes carpenters’ work generally so superior to that of -amateurs, and boys especially are generally careless, and in too great a -hurry to get the work done, that they may go to something else. Remember, -therefore, that when you begin to hurry your work, you begin to spoil it. - -I have made the drawings of the three principal dovetailed joints so -plain as to render special description almost unnecessary after the -remarks already made. The second and third, however, may need a few -words, as they differ slightly from that used in the drawer, of which -a description has been given, chiefly because the piece in which the -dovetails are, is, in this case, as thick as that used for the sockets. - -Suppose the dovetails _and pins_ marked out ready to be cut. Take your -marking-gauge and set the slide about a quarter of an inch from the -point, and run a line across the ends of the two pieces at A B, and at C -D, and also at E F. Stop at A B when you cut the sockets, and take care -to get the bottoms of these quite square and even. Cut the dovetails or -pins as directed in making the drawer, but stop on the lines _e f_ and _g -h_ (the latter also to be made with the gauge on both edges of the work), -thus the two pieces will, of necessity, fit nicely together, and only a -single line will appear a little way from one corner. If all lines are -made with gauge and square, this form of dovetail may require neatness -and care, but will not be beyond the skill even of a young mechanic. I -should indeed advise that every opportunity be taken of joining pieces of -wood with tenon or with dovetail, because, after all, these are the chief -difficulties to be encountered. If you can square up your work, and make -true-fitting joints, there is little in carpentry and joinery that you -cannot accomplish. - -The third example is worked exactly like the second, but instead of -leaving square the pieces projecting beyond the dovetails and pins, -these are sloped off or bevelled carefully from the extreme corners -down to the pins and sockets. The result is, that when put together, no -joint appears, as it is exactly _upon_ the angle. There is no neater or -stronger method than this of joining the sides of drawers, boxes, trays, -and such like articles. The cabinetmaker employs no other for heavy work; -only when it is very light does he make use of a plan, the appearance of -which is (when finished) like the last-described, but it is less trouble -to make, and less strong, yet sufficiently so for many purposes. This -method is called _mitring_, and is accomplished in the following way. - -The wood (let it be for a small tray) is prepared as usual, truly and -evenly, and the ends exactly square to the sides. If you use stuff about -a quarter or half an inch thick, or even an eighth (the first or last -being suitable for such light work), you can make a mitred joint with the -help of the gauge alone, but frequently a _mitre-board_ or _mitre-box_ -is used, which saves some trouble in measuring and marking. It is well, -however, that you should begin with this trouble, and take up the easier -method afterwards; especially as it will in this case give you a simple -lesson in mathematics, and teach you some of the properties of the figure -called a square. Let us commence with this lesson. - -A, B, C, D, Fig. 31, is a square; the lines at the opposite sides are -parallel,—that is, they are exactly the same distance apart from one -end to the other. To make this clear, E and F are given, which are not -parallel, for they are further apart at one end than they are at the -other. And as A B is parallel to C D, and A C parallel to B D, so A B -is perpendicular to B D and to A C, or what we have called _square_ to -it, as you would find with your square, which is made, as you know, to -prove your work in this respect. The consequence is, that the angles (or -corners) are all alike, and are called right angles. Understand what is -meant by angles being the same size or alike. M and H are alike, though -the lines of one are a great deal longer than those of the other; but -though the lines of K and H are the same length, the angle K is much -smaller than that at H. - -[Illustration: Fig. 31.] - -As I have gone a little into this subject, I will go a little further, -for it is as well that you should learn all about the sizes of angles, -and I only know of one way in which to make the matter clear. - -Every circle, no matter how small or large, is supposed to be divided -into 360 equal parts, called degrees. That large circle which forms the -circumference of the earth is considered to be so divided. Now, if we -draw lines from all these divisions to the centre, they will meet there, -and form a number of equal angles. I have not divided the circle P all -round, because it would make so many angles that you could not see them -clearly; but I have put 360 at the top, and then 45, which means, that -if I had marked all the divisions, there would be 45 up to that point. -Then at 45 more I have marked 90, and so on, marking each 45th division, -and from these I have drawn lines to the centre of the circle. Now, if -you understand me so far, we shall get on famously. Look at the line from -360 to the centre, and that from 90°, and see where they join. This is -a right angle, and this is the angle at each corner of a square. At N, -I have drawn this separately to make it clear, and you see I have taken -a quarter of the circle, or the _quadrant_, as it is called, of 90°. -And you now see that I might extend the lines beyond the circle to any -extent, but it would make no difference,—we should still have 90° of a -circle, only the circle would be larger, as those which are partly drawn -with the dotted lines. - -Now, all angles are thus measured by the divisions of a circle; the line -at 45, which meets the line from 360 at the centre, makes with it an -angle of 45°, which is half a right angle. A line drawn at 30° would -make an angle of 30 with the same line from 360, and so on right round; -only when two lines come _exactly_ opposite one another, as 360 and 180, -or 270 and 90, these make _no angles_—they are but one straight line -passing through the centre, and are called diameters of the circle, -a word which means _measure through_, or across the circle. Now, the -corners of a square frame, or of a drawer or box, are right angles of -90°. At R, I have drawn such a corner of a frame, and if I place one -point of a pair of compasses at _e_, and draw a circle cutting through -the lines of the sides of the frame, you see I should make it 90°, or a -quadrant, like N. Moreover, if I draw the sides of the frame as if they -crossed as at _e_ R, I draw a small square, and the line _e_ R is the -diagonal of such square: _e_ R _is the mitred joint I have to cut_. Look -at T S and you will see this, as here the two sides of the frame are -represented as cut ready to be joined together. - -A square has another quality: all its sides are equal, and this is very -important, and will help us in cutting out the work. _x_ Y represents the -strip of wood to be properly sloped off for a mitred joint. With a gauge -such as that just above _x_, or your regular marking gauge, set off on -the side Y a distance equal to _x x_ (the _width of the_ pieces); join _x -b_ by a line, and you will have the right slope. Why? Because when you -measured with the gauge you marked the _two equal sides of a square, -and x b is the diagonal of it_, which is exactly the same as you had at -_e_ R. By measuring in this way, therefore, you can, if your strips are -already truly squared up, always mark out a mitred joint correctly. The -two little angles at _x_ and _b_ are also, I should point out, equal—each -half of a right angle or 45°, and the other strip or side of the frame -will make up the other half right angle, or complete the exact square of -90°. - -In all this I have clearly laid down the principles of mitred joints, -and given you a lesson in mathematics. I shall now, therefore, go on to -the work of practical construction (Fig. 32). You must be very careful -to make the edge B square to the side A, as in all other work which I -have explained to you; or, if this side is moulded like the front of a -picture-frame, you must square the edge with the back. After having cut -all the pieces, you have to glue them and fasten them together. Warm -them, and use the glue boiling, as directed before, and quickly lay the -pieces together. To do so effectually, you must place them flat on a -board or on your bench, and having adjusted them, you can tie a strong -cord round the whole, putting little bits of wood close to the corners, -so that the string shall not mark your work, if such marks would be of -consequence. Or you can wedge up strongly in another way. If you look at -C you will see a square representing a frame with eight spots round it. -These are nail heads, and mark the position of eight nails driven round -but not touching the frame into the bench. Then, having prepared eight -small wedges, drive them in between the frame and the nails. - -You will find this as simple and easy a way of keeping the frame together -as any, and all must remain till the glue is dry and hard—probably till -the same hour on the following day? Then remove the wedges and take up -your frame, which should be trim and strong. Nevertheless, you are now to -add considerably to the strength of it in one or both of the following -ways. - -[Illustration: Fig. 32.] - -With a mitre-saw or tenon-saw cut one or two slits at each angle, as -seen at D, Fig. 32, _e_ and _f_. Cut little pieces of thin wood, and -having glued them, drive them into these slits. If you saw them slanting, -some tending upwards and some downwards, it will be better than cutting -straight into the frame. Then, when all is dry, neatly trim off these -pieces even with the frame. You may also, if the work is of a more heavy -kind, as a large picture-frame, finish with keyed mitres, _g_. Cut a -place with a chisel of the shape here shown, about one-eighth of an inch -deep, half into one piece and half into the other. Then cut out a key -of the same form of thin hard wood, to fit exactly, and glue it in. The -shape of the key prevents the joint from coming apart, and makes it very -strong and durable. A very large number of light boxes are made with -mitred joints, as workboxes, water-colour boxes, compass-boxes, and such -like; and you can examine these for yourself; but you will not often -see the keys at the angles, because most of such boxes are veneered, or -covered when finished with a thin layer of some ornamental wood. - -I shall now proceed to show you how these joints can be cut at once -without the trouble of gauging and measuring to find the proper angle. -Therefore I shall let you into the secret of mitring boxes and mitring -boards, which, if you had much to do of this kind, would shorten your -work considerably. - -Fig. 33, A, represents a mitring-board, B a mitring-box. We must go into -a little mathematics again, and try to understand these, because, if you -do so, you may devise others, occasionally more suitable for any special -work you have in hand. - -[Illustration: Fig. 33.] - -First, look at D of this figure. You have a line, _a b_, standing upon -another C D, and perpendicular to it—that is, it leans neither to the -right nor to the left. It makes two angles at _b_, one on each side of -_a b_, and these are angles of 90°, or right angles, as I explained. -Now, if one line like _a b_ stands on another, these two angles are -_together_ equal to 180°, or twice 90°, whether this line is or is not -upright or perpendicular to the other. Look at fig. C. Here you have the -line _x x_, and standing on it several others; one, _a b_, is upright or -perpendicular, making with it two angles of 90° each, or 180° together. -Now, take _f b_, and suppose this to make 45° on the right-hand side, -you see it makes therefore a proportionately larger angle on the other. -It makes, in fact, an angle of 135°. But 135° added to 45° equals 180°, -which is the same as before, and whichever line you take, the angles -together made by it at _b_ will equal 180° of the circle—that is, they -will equal two right-angles. - -Now, if I take the fig. D again, and carry on the line _a b_ right -through _c d_, where it is dotted, two angles will be made on the other -side of _c d_, which will each be right angles of 90° as before, so that -all the four angles thus made are equal. It follows from this, that -whenever any two lines cut each other—E Q and R S for instance—the angles -at T _equal_ four right angles, no matter whether the lines are or are -not perpendicular to each other: and what is more (and what I specially -want you to note), the _opposite_ angles _are equal_—_i.e._, the two -small ones, or the two large ones. - -The action of a mitre-block or mitre-box depends upon the principles -here laid down, so you see that although few carpenters understand much -about mathematics, and simply work as they were taught, without knowing -or caring why, those who planned the method of work, and invented -mitre-boards and such like devices to shorten work and lessen labour, -must have understood a great deal about such things. And so it is -generally, as you will find with inventions: things look easy enough, and -natural enough, when we see them every day; but it has taken a great deal -of thought and sound knowledge to invent them in the first place, and a -great deal of practical experience to construct them so neatly. Even a -common pin goes through such a number of processes as would surprise you, -if you have never been able to see them made. - -Look carefully at A. It represents a block of wood, about 1½ or 2 -inches thick, and 3 or 4 wide, firmly screwed on the top of a board 1 -inch thick. The length is about 18 inches. Two saw-cuts are made with a -tenon-saw, right through the block to the board, at angles of 45° with -the line _a b_. These are guides for the saw to work in. The wood to be -cut is laid against the edge of the block, and rests on the board, and -the saw is then applied in one of the grooves while the wood is being cut -by it. Let H be such a piece. If the saw is put in the left-hand slit, -it will cut it like _y_; if in the other, it will cut it the other way, -like _x_; and thus, if a piece is taken off at each end, it will be as -you see, ready to become one side of a frame. Now, examine K, which shows -all the lines or edges of the mitring-board, as seen from above, with -the strip _a b_ sawn across in the line _c a_. The lines _a b_ and _c a_ -cross each other, making the opposite angles equal; and as one angle is -45° the other must be 45° also, so that the right-hand side of the strip -is correctly cut. But so also is the other end, and if we turn it over, -it will exactly fit, and the two will form two sides of a square. I could -prove to you that the second strip contains angles exactly similar to the -first, but you ought to be able now to detect the reason for yourself, -and I do not want to teach you more mathematics at present, as I am -afraid you are tired of these, and will want to go on with the real work -of fitting and making. I have, however, said enough, I think, to make you -comprehend _why_ the two saw-cuts must be at an angle of 45° with the -edge of the top board. - -Perhaps you wish to make your own board, however, and would like to know -an easy way to get the saw-cuts at the right angle? I shall therefore -show you how to do this, but you must be very exact in your workmanship. -A B, Fig. 34, is the piece of thick board as seen from above, and close -to it is a perspective view of the same which shows the thickness. Set -off a distance, A E, equal to A C, and join C E. The dotted line shows -you that C E is the diagonal of a square, and the angles at C and E -are consequently each 45°; but we do not want this line to end at C, -it is too exactly at the corner for convenience. Measure, therefore, -a distance, E _b_ and C _a_, equal, and join _a b_, which will be the -place for the saw-cut; and the other can be marked out in exactly the -same way. _a x_, in the perspective view, must be carefully marked by the -help of the square. Take care to mark the line on the bottom board, where -the edge of this upper thick piece will fall, and screw the two firmly -together. If the edge and face of the thick piece are not truly square to -each other, the mitres cut thus will not be correct; but, if all is well -made, they may be glued at once together, no paring of the chisel being -necessary or desirable. - -The mitre-box, Fig. 33, B, is on precisely the same principle, but is -chiefly used to cut narrow strips not over 2 inches wide; it should be -neatly made of mahogany, half an inch thick. There is also generally made -a saw-cut straight across, at right angles to the length of the box or -board, which is convenient in sawing across such strips of wood, as it -saves the necessity of marking lines against the edge of the square: of -course, it is specially used where a large number of strips have to be -cut square across. In all these you observe one saw-cut leaning to the -right, the other to the left. This is necessary when picture-frames or -moulded pieces have to be cut to 45°, because you cannot, of course, turn -such pieces over and use either side, which you can do when the piece has -no such mouldings. - -[Illustration: Fig. 34.] - -Several modifications exist of mitring-boards; some arranged for sawing, -and some for planing; and where thousands of frames have to be cheaply -made, the angles are cut off with circular saws, of which I need not -speak particularly here, but which I shall probably have to describe -in a future page. In Fig. 34, K, I have shown one corner of a simple -picture-frame, covered with what is called rustic work, that is—short -pieces of oak, ash, or other wood cut from the tree, left with the bark -on, or peeled and varnished. These are nailed on with small brads; and, -if well assorted and arranged, this will have a very neat appearance, -suiting well for rooms fitted up in oak, as many studies and libraries -are. In picture-frames, however, a rebate (called rabbit) has to be made -at the back, like L, in which the picture with its glass and back-board -has to rest; and this requires a special plane. The front also is always -either sloped off or moulded. I shall therefore make this kind of work -the subject of my next chapter, and describe the operations of rebating, -grooving, tongueing, and moulding. - - - - -CHAPTER VI. - - -These operations, which are frequently required in carpentry, are done -on a small scale by planes. On a larger scale, circular saws and other -machinery are widely and extensively made use of for the same purpose, -as being much more rapid and economical. Of course, the young mechanic -will employ the more usual method, and the present chapter will therefore -treat of the planes necessary for the above work, and the method of using -them. - -The common rebate or rabbit plane comes first. This is of various widths; -an inch being a very useful size. It is different in many respects from -the smoothing-plane, being made with a single iron only, which is so -arranged as to reach into angular recesses, which could not be touched -by the ordinary plane, of which the iron does not extend quite to either -side of the sole. Fig. 35, A and B, will illustrate this. A represents -the plane as seen from above and at one side, B gives the perspective -view of the sole, C represents the iron, D the wedge. Let us suppose a -rebate required upon a strip 1 inch thick, the same to be half an inch -wide and deep. A gauge is first set to the required distance, and a line -is marked on both faces, as a guide for the action of the plane. After -a little practice it will be found easy to guide the entry of the plane -with the left hand, grasping it so as partly to overlap the sole, and -thus determine the width of the cut, which must not at first be carried -to the full width required, but may be brought within an eighth of an -inch of such gauge line, and the material removed sometimes from one face -of the rebate and sometimes from the other, taking care to keep it nicely -square. - -[Illustration: Fig. 35.] - -At first it is an easier plan to nail on with brads a strip of wood -accurately planed, which in this case, as the sole of the plane is 1 inch -wide, must cover it from end to end to a width of half an inch. This -will prevent the possibility of going too deep into cut, and insure the -correctness of the rebate, Fig. 35, H. The injury to the sole will not be -great if small brads are used, but at the same time it is better to learn -the art of using the hand as a guide, which is the more general method of -the working carpenter. As for the use of rebates, there are few pieces -of cabinet-work or joinery in which they are not found, and as stated -in the previous chapter, no picture-frame can be made without them. The -shavings which escape from the rebate-frame do not rise out of the top, -as in the smoothing-plane, but from the side, which is hollowed out for -the purpose, as seen in the drawing. - -The skew rebate-plane is made like the preceding one, but the iron, -instead of standing at right angles to the sides, is placed at an angle. -With this you can plane across the grain of the wood. - -The next plane to be noticed, is that with which grooves are cut, -such as you will often see in the sides of book-shelves, in which the -several shelves slide. The same is done where two boards are to be -joined lengthwise, and there is danger of their becoming separated as -the wood shrinks in drying. The panels of doors, too, are slid into -similar grooves in the styles and rails of the framework, and there are -innumerable other cases in which this mode of work is carried out. These -grooves are generally cut with the plough, a curious-looking tool, by -no means like a plane in appearance, but of great use to the carpenter. -Of course, we require various widths of such grooves, according to the -special purpose intended, and these are determined by various widths of -the cutting irons, which, however, all fix into the same stock; a dozen -or more of such irons are sold with a single plane. - -[Illustration: Fig. 36.] - -In Fig. 36 is a set of drawings explanatory of the above tool. The -central part, or stock, is that which corresponds to the same in other -planes, and it is only modified to suit the other parts, which simply act -as guides or gauges regulating the distance of the grooves from the edge -of the board, and the depth to which they are to be cut. When the arms, A -A, are removed, you have the plane as it appears with a brass fence, _b_, -at one side, which can be raised or lowered at pleasure, and set at any -point by the screw C; _d_ is an iron plate which acts as the sole of the -plane, the cutting edge being set to project a very little way below it. - -The arms A A carry the fence _g_, which is flat on the inside next the -plane, and moulded (merely for appearance sake) on the outside. The arms -slide in two holes in the body of the plane, and can be drawn out at -pleasure, and fixed by little wooden wedges, _e e_. Thus, while in use, -the fence rubs along the edge of the board, while the groove is being -cut at such distance as the fence is fixed, and to such a depth as is -allowed by the position of the brass check or guide. Complex, therefore, -as this tool appears, it is not so in reality. We shall presently -describe a chest of drawers or cabinet calculated to receive small tools, -or specimens of coins, shells, and such like, in which another kind of -grooving-plane has to come into use, called (with its fellow, which makes -a tenon to fit such groove) a match plane. This is of extensive use, less -expensive than the plough, and on the whole more likely to be useful to -the young mechanic. Indeed, although the plough has been here described -and illustrated, it is not by any means to be considered essential, -and its purchase may well be deferred until other tools of greater -importance has been effected. The side or sash fillister to be presently -described, for instance, would be more useful. - -[Illustration: Fig. 37.] - -Fig. 37 is such a cabinet, with six drawers, dovetailed at the corners as -usual. The bottom, however, projects beyond the sides, so that the latter -are not made lower than the back, as was the case with the table-drawer -previously described. The top and sides may be of mahogany, the back -and bottom of pine (stained or not at pleasure), or if cost is an -object, the whole may be of any other wood; but the grooves in which the -drawers slide, can be cut more sharply and neatly in harder wood than -pine—birch, for instance, which is very fit for the purpose, and will -take a good polish. The outer case is first made like an open box. The -dimensions may be regulated according to the intended use, but generally -the drawers increase in depth downwards. The top and bottom overlap the -sides, the latter to a somewhat greater width than the former. The sides -can therefore only be dovetailed to the back; the bottom may be attached -with screws, and the top likewise, but the holes must then be plugged to -conceal them. If the whole is of deal, and to be painted or veneered, -this would be the best plan; but if the top is of mahogany, it is not -so easy to fill up the holes above the heads of the screws so as to -thoroughly conceal them. If, however, you have no plough to cut a groove -to let the sides and back a little way into the top, glue alone will not -hold sufficiently. In this case smaller holes may be made to admit 2-inch -brads to assist the glue, such holes being easily filled with putty -stained to imitate mahogany. - -The peculiarity of the drawers consists in their meeting each other quite -closely when shut, without the intermediate divisions ordinarily seen. -Hence the necessity for a different arrangement of the sliding surfaces -as before referred to. The insides of the case have _five_ grooves -ploughed across them, as seen at C of this figure, the sixth drawer only -being made as usual to slide upon the bottom of the case, and having its -sides made lower than the back for this purpose. - -In the grooves thus cut, the projecting part of the bottom of the drawers -is made to fit and slide, and they will run more smoothly if cut so that -the grain of the wood shall run across the bottom, from front to back, -and not from side to side. The bottom of the drawer must not come below -the level of the front, but either the front should be rebated to take -one edge of it, as seen at E, which is the best way, or a slip of wood -should be glued along as at F, on which that edge may rest, and to which -it can be attached. D exhibits this distinctly, as it is drawn as if the -nearest end was removed to show the position of the other parts. The -bottom, therefore, will be let into the front, and nailed under the back -and sides, and will project rather less than half an inch each way, to -fit the grooves in which it is to slide. Another way to effect the same -is to make the drawers as usual, with no such projections, and to nail -a strip to run in the grooves in the middle of the side pieces, or, if -preferred, near the top. The effect is, of course, the same, and such -strips being planed up nicely, with the grain running lengthwise, will -cause the drawers to work in and out very smoothly. - -There is no neater way than this to make a cabinet; and sometimes the -whole is closed with a panelled door, for which purpose the case is -left to project beyond the drawers. Unless well supplied in the matter -of planes, which is hardly to be expected, you will not be able to cut -the grooves in the side of the outer case in any way but the following, -which, however, will answer very well when the piece in which they are -to be cut is not above 9 inches or 1 foot wide. Mark out the places, -spacing them with the greatest care, and cut just within the lines with a -tenon-saw; then cut out with a chisel the narrow piece which intervenes. -There is a plane called a routing-plane used for this by cabinetmakers -and joiners, but you may as well exercise your ingenuity to do without -it. If you have a plough, you may remove the fence, and let it follow up -the saw and chisel, but it will be hardly required if you use the chisel -carefully. - -I shall now introduce to your notice another very excellent plane, called -a side or sash fillister, for cutting rebates of any required depth and -width. It is very like the plough in appearance, with a similar wooden -guide or fence on two arms to regulate the width, and another of metal, -moved by a screw at the top, to regulate the depth of the cut. Fig. 38, -A, shows one side of this plane, and B the other. The cutting edge comes -down to the level of _c d_ in fig. A; the fence, of which the edge is -seen at _h_, will draw up to the level of _a b_, or lower to that of the -edge. This plane, therefore, is but a more complete rebate-plane, fitted -with guides for depth and width. It does its work very perfectly, and is -of extensive use. - -[Illustration: Fig. 38.] - -I have given descriptions of these planes, although the young mechanic -will not at first possess them, as they are somewhat expensive, because -I feel it as well to let him know how work is done by the trade, and -why it is that such work is effected more rapidly and better than he -himself can do it; but at the same time it is far better that he should, -for a long time, work at a disadvantage, by using few tools, and those -of the simplest construction, before taking in hand others which cost a -good deal of money, which might often be better spent. A look back over -these pages will show that with a long (or jack) plane, a smoothing-plane -and a rebate-plane, all the work previously alluded to can be done. As, -however, I am writing upon the subject of planes, I may as well mention -two more—match-planes and beading-planes—to which may be added those -for moulding, being an extension only of the last named. Match-planes -are always in pairs. Their use is to cut, the one a groove, Fig. 39, A, -the other a tenon or tongue, or feather, as it is sometimes called, as -Fig. 39, B, down the long sides (with the grain) of boards that are to -be joined lengthwise (Fig. 39). If the plough is used, a groove is cut -in both pieces, and a slip of board planed up to fit them; either method -will answer equally well. When boards joined thus shrink, the tongue or -slip fills up space. - -[Illustration: Fig. 39.] - -There is no necessity for illustrating the planes used for beading -and moulding after the description already given of others. The irons, -instead of being flat, are filed into grooves and hollows of the required -pattern, and of course transfer their own form to the wood upon which -they are used. They are held on the slope of the moulding to be cut. -When blunt, they have to be sharpened with slips of oilstone, which can -be had for the purpose, of square and round section; sometimes they are -sufficiently soft to be filed into shape, but a keen edge cannot thus -be obtained. Mouldings, however, are generally finished off with fine -sandpaper. They are always planed lengthwise of the grain in long strips, -and are cut to the required lengths (generally with mitres). When very -broad, they are made up of several narrower ones, glued side by side. -The young mechanic had better get them cut for him by some friendly -carpenter, as it is hardly worth his while to buy planes for which he -will have comparatively little use. - -I shall conclude these papers on carpentry by describing the method -of making such a door as would suit the cabinet already described, -especially as it will explain the way in which all panelling is done, -whether for doors, shutters, or other similar articles. Panelling is -indeed of very general application in every household, and it is well -worth while even for the young mechanic to learn how it is accomplished. -It is absolutely necessary, however, that he should be possessed either -of a plough or match-planes for routing out the grooves in which the -panels slide. - -Nearly all panels have a beading or a moulding running round them as a -finish. - -[Illustration: Fig. 40.] - -Fig. 40 illustrates the method of panelling. A, B, C are the styles, D, -E, F, G the rails. The mortices and tenons are cut as usual. The inside -edges of C, B, D, G are then grooved with the plough, and both edges of -the other pieces. The panels are carefully squared up, and then bevelled -off at the edges so as to fit the grooves. To put such a door together, -A, D, G, E, and F would be first arranged, then the panels slid in -from the outside, and afterwards the styles B and C put in place. The -part beyond the outer mortices in the latter pieces, which are left for -safety in cutting these mortices, and to prevent splitting when D and -G are driven home, are not cut off until the glue is dry. The process -is simple, but it requires great care, both in setting out the various -measurements, and in squaring up the different pieces composing the -whole. After the whole is dry, strips of moulding, cut to mitre-joints at -the corners, are nailed on with brads round the panels to give the whole -a finished appearance. - -In the above examples, in which I have gone from the more simple to -the more complicated, are comprised the main principles of the art of -carpentry. At any rate, when the young mechanic can do _as much_, he will -be able to accomplish a great deal more. - - - - -CHAPTER VII. - - -There are a number of useful and ornamental articles which cannot be -made with the carpenter’s tools alone, but which need a lathe for their -construction. Wooden boxes of circular section, wooden and metal wheels -and pulleys, ornamental chair and table legs, and a countless number of -similar articles, all depend upon the skill of the turner. Models too -of engines and machinery of all sizes and shapes, bring the lathe into -constant requisition. - -No one can say to whom this machine is to be attributed. Probably it has -been developed by slow and imperceptible steps, from the potter’s wheel -to its present elaborate and perfect form. As for the part that old -Dædalus had in it, I believe he had just as much to do with it as he had -with the saw, which he is said to have invented from seeing the backbone -of a fish. Now, the backbone of a fish is not a bit like a saw, but the -jaw of a shark is, and very quickly it amputates legs, arms, and heads, -when unfortunately the chance is given to it. We need not, however, stay -to discuss this unimportant point; we will leave it to the researches -of the Antediluvian Society, or Noahican Brethren, or any other known -or unknown learned body, and proceed to consider the lathe as it is -now generally constructed—the ambition of boys, the delight of adult -possessors, and, to the writer, “gem of gems!” - -At the very time I write, I am engaged in fitting up two lathes; one of -which is for just such a “young mechanic” as this book is intended to -instruct. The bed will be of dry hard beech, the fly-wheel of iron turned -up with five grooves or speeds, as they are called. The heads, which are -the only really important part, are to be made by a well-known London -maker, whose work is sure to be the best possible at the price afforded. -Nevertheless, this lathe will cost several pounds, although it is to be -fitted for hand-turning only, and it is possible in London to find a much -cheaper (not better) article. - -When I was myself a “young mechanic,” so many years ago that I find I -do not quite like to count them, I had a lathe at £2, rather shaky, -wooden fly-wheel, wooden head—not at all the thing to recommend. Then -I had another made by a gunsmith—all iron—for it was what is called a -triangle-bar lathe; the bed being a bar of triangular section, on which -the heads or poppits slid, and also the rest. I think now it was not a -bad lathe; but I am afraid the work I did on it was scarcely first-class; -and I sold the machine one fine day under the impression that if I had a -better I should do better work. This, however, proved a terrible fallacy; -so I set myself upon high as a warning to young mechanics, who always -fancy that their clumsy, bad work is due to some fault in their tools, -whereas, after all, it is generally their own. - -Well, I had a succession of lathes, after that triangle-bar one had -passed into oblivion, by various makers; some good, some indifferent, -some for heavy, and some for light work; and I fancy I am now fairly able -to give an opinion upon the merits or demerits of any particular lathe -which may come under my notice. - -I was going to write a piece of advice, “_Don’t give too much for a -lathe_,” when I remembered that I was scribbling for the edification -first of boys; and experience tells me the caution is by no means -generally necessary, few boys’ pockets being very heavily lined, owing -to the constant claims upon them for peg-tops, knives, string, and -etceteras—not to say lollipops and bulls’ eyes, and similar unwholesome -luxuries. - -I suppose, however, I must give some idea of cost, if only as a partial -guide; but all depends upon the special object for which the lathe is to -be used. If for models, for instance, it would not be so expensive as -if it was desired for elaborate ornamental work in wood or ivory, when -the young mechanic has grown whiskers, and become an adult enthusiast at -this delightful recreation. For there are all kinds of lathes to be had; -some that will answer well for beginners, and for rough work in after -years; some beautifully finished, intended to be used first for simple -hand-turning, but which are of best construction, and therefore worth -adding to from time to time; and if carefully used, will descend in good -order from father to son. Then there are lathes for heavier work, and for -screw cutting and engine making, fit for engineers; and others of minute -size and exquisite finish, adapted to the special requirements of watch -and clock makers—lathes you could put in your waistcoat pocket. - -Now, if I were sure you would be very, very careful, I should like -to recommend a good lathe, worth adding to as you grew more and more -experienced; but these, even of simplest make, are costly, and not within -reach of half my readers. I shall therefore say—get a good, plain, -strong tool that will bear a little rough usage, and which will cost you -as little as it is possible to make them for: and if you find, after a -year or two, that you are becoming a proficient, and therefore not so -likely to damage a _good_ lathe, you can set this, your first, on one -side, and let it become your _hack_ to do any odd jobs, and buy yourself -both a larger and a better one. I know this will be a _double_ outlay; -but experience tells me it will be the best way and the cheapest in the -long run. Perhaps you may like to go on as you are. Your small lathe may -prove an accurate one, and quite sufficient for your need. In such case, -of course, a new one will not be required at all. But if it should be -otherwise, and circumstances allow you to improve upon it, you may rest -assured your old friend will be ever a handy assistant, and save your -better lathe very considerably in many ways. - -You can get a lathe for about $20 to $25, with iron bed complete; and I -really think it impossible to obtain a cheaper one. Of course it will be -small, and of the plainest possible construction. It will, nevertheless, -answer for light work in wood and metal, being designed to assist the -young mechanic in making model engines and similar curiosities. From this -you may go, pound by pound, to good, serviceable tools; and these to a -£300 lathe for rose engine-work, and elaborate ornamentation in ivory -and other costly materials. Most probably I shall be able to give you a -catalogue or two at the end of this book, published by makers of such -lathes, and you can then judge of the probable cost of your workshop. The -drawing of the lathe (Fig. 41) will be readily understood even by those -boys who have had no opportunity of seeing any work of this kind. There -are, however, few towns or villages in which a lathe does not exist, and -may not be examined by any boy who desires to learn its construction and -use. Its object is to give rotary movement to any material it is desired -to form into a circular or cylindrical shape. - -[Illustration: Fig. 41.] - -Motion being given to the fly-wheel by means of the treadle and crank, -is communicated to the pulley upon the mandrel. Upon the screw of this -mandrel, B, the work is fixed; being usually held in a chuck suited -to its particular form, but sometimes it is screwed directly upon the -mandrel. The rest, C, is then fixed near it, and the tool is supported -thereon and held firmly while the work revolves against it. All this -is easy to understand—it is _not_ so easy to carry it into practice. -Attention to the following directions will enable the young mechanic to -become a good turner in course of time; but the art cannot be practically -learned in a day, and it needs experience and considerable practice to -become anything like a proficient. - -If the construction of the lathe itself is understood, the first -consideration is what tools and chucks are necessary. I shall speak -of the latter first, as little or nothing can be done without them. -First comes the prong-chuck, for soft wood (Fig. 41, A). This, like all -others, is made to screw upon the mandrel. Its use is to hold one end of -any piece of wood while the other is supported by the point, E, of the -poppit, H, which poppit can be moved at pleasure along the lathe-bed, -and fixed at any given place by a hand-nut below. The point itself can -be advanced or drawn back by turning the handle, K. A piece of wood thus -mounted must of necessity revolve with the mandrel, because, although -it can and will turn round upon the point of the back poppit, it cannot -do so upon the fork or prong, which enters and holds it securely. -This chuck, or one of the same nature, is always used for cylinders of -soft wood, which can be supported at both ends, such as tool-handles, -chair-legs, and other work not requiring to be hollowed out. - -It sometimes happens, however, especially if the work is at all rough, or -considerably out of truth, that the piece slips round upon the fork or -prong, especially if it does not enter deeply enough; and in addition, -tool-handles and round rulers, and many articles that have to be -similarly supported at both ends, are made of hard wood, into which this -prong will not readily enter. - -In such cases, and indeed as a general substitute for the first, a chuck -called a “cross-chuck” is to be used (Fig. 41, L, M). The _centre of -the little_ cross (which is of steel, and fits into the same square or -round hole in the socket which carries the prong, and which is also used -to hold drills, pieces of iron rod which are to be turned, and other -articles) is made to revolve in the precise axial line of the mandrel, or -to run _true_ with it, as it is called. The arms of the cross are to be -imbedded in the work, which is best effected by making in the latter two -saw-cuts at right angles with each other (Fig. 41, N), which represents a -piece ready for mounting. - -The next chuck is equally necessary (Fig. 41, O). It is a taper screw of -steel, fixed in a socket which can be attached to the mandrel. Two sizes -of this chuck would be useful for a large lathe, but for such a one as -will probably be purchased by the young amateur, one only, with a screw -of medium size, will suffice. The use of this chuck is to hold pieces -which only require to be supported at one end, so that a tool can be used -to work upon the other, either to mould it into the required form, or to -hollow it out for a box or bowl. Of course you might screw such work on -the mandrel-nose itself, but it would make a very large hole in the end, -whereas this taper screw only requires a moderately sized gimlet-hole. It -is therefore a much more convenient way of attaching work to the mandrel, -and is of extensive use. - -The cup-chuck is the last required. It is sketched at P, and is sometimes -of iron, but generally of brass. There are several sizes made and sold -with lathes, but you need not have at most more than one or two, as I -shall show you how to make wooden ones, which answer as well, if not -better. The flat plates, R, R², can scarcely be called chucks, but they -generally come into the list of such. The latter has five projecting -points, which, sticking into such a thing as a flat-board (like a -bread-platter, or round pulley), hold it sufficiently firm when the back -centre is brought up against the other side of the piece, to allow of its -being turned. The other is merely a flat plate with holes in it, through -which screws can be passed from behind into any odd bit of wood of 2 -or 3 inches in thickness, whereby a chuck can be quickly made to suit -any required purpose. Two or three of these would be convenient, one of -which should be nearly as large as the lathe will carry; and in this one -a great many holes and slots should be made. This is called a face-plate, -and, in addition to the ordinary screws, whereby pieces of wood are -attached to it, it is fitted with clamps and bolts of various forms, for -the purpose of holding securely upon its face all kinds of flat works in -wood or metal,—such as cog-wheels, which have to be bored out and faced. -The young model-maker will find a face-plate of great service. The larger -one should be of iron, as it will be cheaper than brass. - -We now pass on to chucks for metal turning. These are of various shapes. -First in order comes the centre chuck and dog, for holding rods of iron -which can be supported at both ends. The commonest form is represented in -Fig. 41, S, T. S is such a face-plate almost as I have described, but it -has a pin projecting from it, and also a steel centre-point. The latter -is often made to screw out and in, which is the best plan. The pin can be -slid to any point in the face-plate, and clamped by a nut at the back. T -is called a dog, and of these two at least will be required, if the young -mechanic intends to work in metal. - -The way of using these is shown at T². The rod of iron has a hole drilled -at each end, as nearly in the centre as possible. It is first indented -with a punch, then a drill is put into the drill chuck, and one end -of the rod brought against it as it revolves, while the back poppit -centre-point is screwed against the indentation at the other end. A -little oil is applied to the drill to assist its working, and the rod -itself is prevented from turning round either by grasping it with the -hand or screwing a hand-vice upon it, so that this comes against the bed -or the rest; or it can be held in the hand, which has one advantage, -namely, that the operator can feel exactly what is the resistance caused -by the drill, and can regulate the pressure accordingly. The screw of the -poppit is, of course, to be very slowly and steadily advanced during the -process. All _drilling_ in the lathe is done in this way, but in boring -out long holes, the action is often reversed, the work being kept in -motion while the tool is advanced, without being allowed to revolve. You -need not bore more than one-eighth of an inch for light work, but must do -the same at each end of the rod. The holes thus made should be of such -a size as not to let the extreme end of the back centre-point touch the -bottom, or it will soon be worn down and blunted;—remember this in all -future work. - -Supposing the rod to be thus bored at each end, place the centre-chuck -upon the mandrel, instead of the drill-chuck, and mount the bar between -this and the point of the back-centre. Thus placed, it will be accurately -supported, but if the lathe is put in motion, it will not turn round. -Now come into use the little dogs. Remove the bar, and choosing a dog of -which the open part is tolerably near the size of it, slip it over the -end about half an inch, and there fix it by tightening the little screw, -which, you observe, will drive the bar as far as possible towards the -smaller part of the opening, and when it can go no farther, will secure -it as in a vice. It is a good plan to file a slight flat upon the bar, -just where the screw of the carrier will come. Now replace the bar, and -when the lathe is put in motion, the tail of the carrier should come -against the projecting pin in the face of the face-plate, which will -compel the iron to go round with it. This is the way all bars of metal -are mounted. I shall not tell you yet how they are to be turned, because -this would interfere with the order of my description. - -To mount in the lathe such pieces as cylinders of engines, which require -to be bored, or any other objects which have to be turned on one or both -faces, the young mechanic must make wooden chucks, and bore them out -exactly to fit the article and hold it securely. There are metal chucks -expressly made to take all work of this kind, and which are so contrived -that they will also hold it truly central, but they are costly, and need -not be obtained with the first lathe—at any rate, not until _absolutely -required_, and that will be, I know, a long time hence; ay, a _very_ long -time, for many good workmen have never even _seen_, much less possessed -one of them. Perhaps I may draw and explain one in a future page, as well -as some other chucks, which it is not necessary to notice here. - -The chucks then absolutely necessary are these— - - 1. SQUARE HOLE CHUCK, which will take the prong, the cross, the - drills, and short bits of iron to be turned. - - 2. THE TAPER SCREW. - - 3. FLANGE or FACE CHUCKS, one with five points, and two with - holes for screws, also one larger for a face-plate. - - 4. Two or three CUP-CHUCKS (I can, however, scarcely call these - _absolutely_ necessary). - - 5. CHUCK FOR IRON, viz., face-plate with centre-point, and two - dogs to take iron from 1 inch diameter down to quarter-inch. - These should have pear-shaped openings, not round; any - blacksmith can make them, but somehow they do such work - generally in a clumsy fashion; and they cost but 35 to 75 - cents, according to size, beautifully made with turned screws. - -Now as to tools. Their name is legion—tools for iron, brass, ivory, -hard and soft wood; and many an odd shilling will be well laid out from -time to time in adding to the stock. Happily those most needed are not -costly—about $3 a dozen without handles, which latter may be had at 10 -cents each and upwards, according to the material and finish, all with -iron or brass ferules, so necessary to prevent splitting. You may buy -your first few simple tools handled, but after you have these you can -turn as many handles as you like, and you can buy ferules of all sizes at -any regular tool-shop. - -I may as well tell you that in a great many country towns you will be -unable to obtain turning tools except gouges and chisels, so that when -you buy your lathe in London, as you will find the best plan (or in -Manchester, Birmingham, or other manufacturing town, if nearer to you), -you must lay in a little stock of tools at the same time, and take future -opportunities of getting more. In regular tool-shops you will have them -laid before you by dozens of every conceivable shape and size, so that -your great difficulty would be what to pick out if it were not for some -such directions as I am now about to give you. - -First, you will want gouges and chisels. Begin with two sizes of each—one -of half an inch, the other of 1 inch in width. These are to be mounted in -long handles. - -Now, with these alone you can do all the plain work in soft wood which -does not require to be hollowed out, tool-handles, chair-legs, legs of -towel-horses, round rulers, and all sorts of things, and to a certain -extent you can turn out the insides of wooden chucks, bowls, and boxes, -but not very easily with these alone. Hence you must add some of those -shown in Fig. 42. These I shall endeavour to assort as follows:— - -A to F are for hollowing out hard woods; G and H are hook-tools (very -difficult to use) for hollowing out soft wood boxes and bowls. - -[Illustration: Fig. 42.] - -I and K show the edge and side of a parting tool for cutting off the ends -of cylindrical pieces, separating the turned from the unturned parts, and -for all similar work. [A tenon-saw held still against a piece revolving -in the lathe will often serve to cut it in two, but parting tools must -also be had, and two are better than one, as a thick one should be kept -for common woods, and a thin one for ivory and precious materials; -sometimes one with a _notched_ edge is used for cutting off soft wood.] - -L to O are for turning iron and steel. The first is a _graver_, of which -all sizes are made; one of a quarter inch width on either face is large -enough. It is a square bar of steel ground off cornerwise so as to form a -lozenge-shaped face. This is an essential tool for iron, and will do all -sorts of work. - -M is a hook or heel tool, made sometimes with a flat edge and sometimes -with a rounded one, the latter being most useful. It is a very powerful -tool, much used by some, especially for heavy work—I don’t think you need -get one at present. If I am able to teach you to use a graver it will -do almost as much work, and is a neater tool. If you use a tool of the -nature of heel-tools at all, I think, on the whole, the nail-head tool, -N, either round or square, is the best. It is at all events handy for -roughing down work, and when it is reduced nearly to the size required, -and is partly smoothed, the graver will finish it. - -O is an inside tool for hollowing out iron. There are different shapes -of this used, each turner giving the preference to some particular -pattern to which he has habituated himself. None of these tools for -metal have sharp edges—at least they would not appear so to an ordinary -observer. The angle of the edge is 60° to 80°, or even 90°, which is, as -you know, a right angle, and is that most generally used for the cutting -edges of tools intended for brass, as U, V, W, of which V is a most -useful pattern. Those for hard wood have edges a little more keen, but -after all they scrape rather than cut; the only tools for wood with keen -edges being the gouge and chisel. - -P are callipers for measuring the _outside_ of work of all kinds. Q and R -are the same, arranged for in and outside work. The first is an ordinary -pair closed until the ends have crossed, which they will all do; but if -the inside of hollow work to be gauged is small, they will not enter it. -In this case none are so generally useful as the in-and-out callipers, -R, for when accurately made (and if not you can easily correct them with -a small file), the one end will measure the external diameter of work, -and at the same time the other end will be found to have its points -separated to such a distance, that if you were to turn a box or chuck to -this inside measure, the cylinder first turned will exactly fit it. Thus -if you turn a box-cover, and take the size of it with the straight end of -the callipers, and then turn down the rim of the box until it is just the -size indicated by the curved ends, the one will exactly fit the other. -In turning a piston to fit the cylinder of an engine, you would work with -this useful tool. - -S is the turner’s square. The blade slides stiffly and accurately in a -slot in the brass, being kept by a spring at one side from working loose. -This square is used to gauge the depth of boxes and other works which are -to be turned to an exact size, and it also serves to test the squareness -of many kinds of work. Suppose, for instance, you had turned a box, you -would put the blade of this tool against the bottom and press upon it -till the brass rested across the rim, touching it in two opposite places. -Now possibly the inside may be smaller at the bottom than at the top. -Test it by bringing the steel blade edgewise against it. You will see -whether the brass still touches in two places across the mouth of the -box. The squareness of the outside with the top or bottom can be tested -in a similar way. We shall have occasion to recur to this when we come to -boring and fitting engine cylinders. - -S² is another small square, which is often serviceable where the -carpenter’s square cannot be used. If you intend to make models, you will -want both of these; at the same time, it is quite possible to make the -latter of iron, or even thick tin, if you have the former, as an accurate -guide to work by. - -T represents a pair of spring-compasses or callipers. They are used to -set off distances, and have the advantage of not being liable to shift -their position when once they are set to any required width. You will -require a pair of compasses of some sort, and if not already provided, -these are the best you can have. - -There are many other tools, which, though not absolutely turning tools, -are more or less used in connection with the lathe, but these need not -now be further alluded to, and I shall go on to describe as clearly as -possible the method of working at the lathe with hand-tools, commencing -with the operation of turning soft wood with the gouge and chisel; but I -must first give a short chapter upon the nature of woods used. - - - - -CHAPTER VIII. - - -As different materials require somewhat different management, and even in -the matter of wood alone this rule holds good, it may be as well to have -some idea of what is meant by _hard_ and _soft_ wood. - -The young mechanic has most likely hitherto considered all wood under -one head; but there is a vast difference, nevertheless, in the internal -structure, even of such kinds as grow in England; and the woods of -foreign countries differ again from these, some being of such close -texture that it is almost impossible to work them with ordinary tools, -and some (such as the palm) being little else than gigantic ferns, -and in structure like that much-dreaded implement of flagellation—the -schoolmaster’s cane. - -In England the hardest wood found is that of the box-tree, the chief -place of which is in Surrey, at Box Hill; it is, nevertheless, found -scattered here and there in all parts of the country, but not generally -of a size greater than 3 inches in diameter. It is of very slow growth, -and our own country would not nearly satisfy the demand made for it by -various trades. Hence a large quantity of box, of larger growth, and -generally of harder and better quality, is imported every year from -Turkey, to be used in the construction of blocks for engravers, who alone -require many tons weight annually, and for carpenters’ rules, mallets, -turned boxes, and tool-handles; to which I may add the important item -of peg-tops. I fear some of my readers may think I should have placed -these first on the list! Opinions, however, I imagine, differ in this -particular, as in most others, and upon all subjects. - -The grain of boxwood is so close and even that it is one of the most -valuable turning materials we possess. It takes excellent screw-threads, -provided they are not too fine; is a very general material for boxes of -all kinds, and also for chucks, although there is really no reason why -it should be wasted in so applying it, when other woods of less value -make such efficient substitutes. Probably its use for this purpose arose -from the facility with which a screw can be cut in it to fit that on the -mandrel, and that it is so hard as not to allow the collar beyond the -screw to make much impression upon it. In consequence, when it is well -fitted, such a chuck can be screwed on many times exactly to the same -point, and will continue to run true. But I myself have found that if the -mandrel-screw is not very coarse, the threads cut in the inside of the -chuck are apt to break off. - -Somewhat similar in texture, though by no means generally used, is the -wood of the ELDER, which is quite different, be it observed, from the -ALDER, although I often hear the names confounded together. The wood -I allude to is that of the tree which bears umbels of sweet, white -blossoms, which give place to those jet-black berries we find upon them -late in summer, and which are made into elder-wine, for home consumption -at Christmas, when, no doubt, most of my readers have drunk it, hot and -spicy and sugary, to keep out the wintry cold. From the same tree are -commonly made those harmless engines of mimic warfare—pop-guns! - -If it were not for the presence of the pith, which is in fact the very -quality which makes it valuable to boys for the latter purpose, this wood -would certainly have been eagerly seized upon by turners. Even with this -defect, it is used instead of box for the inferior kinds of carpenter’s -rules and other purposes, and the larger pieces will make very good -chucks, if a little care is exercised to prevent splitting them. It is -indeed a wood that might be far more extensively used in this way than it -is. - -The YEW, perhaps, should come next in order, for this too is very -close-grained and very beautiful, and when highly polished it will bear -comparison with many foreign woods which we import at a high price; it -is, however, brittle and apt to splinter. - -WALNUT varies considerably in quality, some being harder and richer in -grain than others. This wood, however, is not to be classed among those -which are properly speaking _hard_, as it can be cut with ease, and can -only be planed and worked as deal would be, viz., _with the grain_; -whereas the hard woods work with _almost_ equal facility in either -direction. This indeed in a great measure constitutes the difference -between soft and hard woods, in the turner’s sense of the words. If you -were to hold a chisel flat on the rest, so as to let it scrape a cylinder -of wood as it revolved in the lathe, you would find in some cases that -it would tear out the fibres in shreds—_these are soft woods_. In other -cases it would leave the surface rough but otherwise tolerably even, and -with some it would leave the same fairly turned. - -I cannot call to mind any English wood but box that can be turned by a -chisel held so as to scrape it, but the greater number of foreign woods -are always turned in this manner, being hard and close in the grain. - -BIRCH.—Oh, once-dreaded tree! birch! with its long, swaying, switchy -boughs, drooping as in sorrow at the mean uses to which it was applied! -It is nevertheless a very useful tree, and the young mechanic can take -full revenge upon it by cutting, and chipping, and turning it into all -sorts of useful articles. It is, however, now more generally used in -cabinetmaking, for wardrobes, bedsteads, chests of drawers, and such -like, as it looks very neat when planed and varnished. Perhaps, as a wood -for the exercise of the turner’s art, it must give place to - -BEECH, which is a common and excellent material for the essays of -beginners, who can turn tool handles especially from the small trimmed -billets of it which are kept by the chairmakers, and which can generally -be bought for a trifling sum in any town, and in many villages. If not, -the wheelwright may be applied to for a supply, as he uses it rather -extensively for the felloes of his wheels. It is peculiarly liable to the -attacks of the little worm, weevil or maggot, who drills such innumerable -and such beautifully round holes in furniture that stands long unused. - -Beech is often used for the screws of carpenters’ benches, as it takes -very well a thread of such size as is required for that purpose. It will -also, for the same reason, answer very well for chucks, for which it has -the recommendation of cheapness and toughness. - -ASH seems to come next upon the list. It is probably the most useful -of all English woods, and where toughness, pliability, with moderate -hardness, are valuable qualities, no English wood can exceed it. For -frames of carts and carriages, shafts, agricultural implements, -wheelbarrows, and smaller articles of husbandry, it is precisely what -is needed, and in the workshop of the turner it is equally valuable. -Tool-handles of ash are very durable, and hold the tool with great -firmness, owing to the natural elasticity of the material. It may be -stained and polished, and is then, for real _work_, preferable to the -more costly hard woods of which handles are very generally made for the -workshops of rich amateur mechanics. - -OAK is little used for turning, the grain being too coarse. The young -mechanic need never make use of it for this purpose, and the same may be -said of the elm. - -ELM is, nevertheless, used by turners for the wooden buckets of pumps, -and is a generally useful wood. Bulk for bulk, it is lighter than beech, -and it makes a good material, it is said, for lathe beds, though beech -is more frequently used. It will answer for chucks, as indeed most woods -will that can be cut into screws; it is very tough. - -EVERGREEN OAK, or HOLM OAK, as it is called, is very different to the -forest tree, and might be classed among shrubs. When dry, it is by no -means a bad wood to turn, and will take a good screw thread, and make -excellent chucks. - -ACACIA is an excellent wood. It is of a yellowish brown colour, tolerably -hard, and will take a good polish. It is most certainly to be set down -among the woods valuable to the turner. - -SYCAMORE is white, very soft until old, when it becomes much harder. This -is also a turner’s wood, and used extensively for wooden bowls, backs of -brushes, turned boxes, and what is generally called “turnery.” A little -of this will be useful to the young mechanic. It will make excellent -bread platters, stands for hot water jugs, and such like. - -HOLLY.—The Christmas garland, with its red berries decorating even the -poorest homes in midwinter, is a tree well worth the attention of the -young mechanic. It is his substitute for the more precious material -ivory, and from it he will turn the white draught or chess men, boxes, -and many small articles. But it is necessary that this material should be -perfectly dry, and to get it in perfection, carefully preserved to insure -its whiteness, it will be generally necessary to procure it ready for -the lathe at some lathemaker’s, or at first-class cabinetmakers’. If cut -green, it requires long seasoning, during which it shrinks considerably. -In fact, it takes some years entirely to rid it of the great quantity of -moisture which it contains. It is well worth procuring, nevertheless, for -it is nearly as white and free from grain as ivory. - -Many of the fruit-trees of our orchards and gardens supply good material -to the turner. APPLE, PEAR, CHERRY, PLUM, and some others, are all more -or less useful. The grain of the first is rather dark, the fibres often -twisted. It looks well when polished. - -PEAR has a very fine, even grain, and is largely used for making the -curved templates (or patterns of curves for architects and engineers); it -will make good boxes, and is fairly serviceable to the turner. Its colour -is light brown, but darkens by exposure. - -The PLUM has a wood veined very like that of the elm, but is a finer and -better wood for the lathe. This is the _wild_ plum, and not the grafted -fruit-tree of our gardens, which is not nearly so good. The wild plum is -excellent for small boxes, and looks well when nicely turned and polished. - -CHERRY is a very excellent wood, and naughty, fast boys, who take to -smoking, like young Americans, when they ought to be filling their young -brains with knowledge instead of narcotics, know very well that it is -made into pipes and stems of pipes. Happily this is not its only use, -for it is fit for many other purposes; and for light, elegant furniture, -it is scarcely to be equalled. Dipped in lime-water, it darkens, and by -doing this here and there, a beautiful mottled appearance is given to it. -It takes an excellent polish, and should be among the stores of the young -mechanic. - -We now come to another soft, white wood. The LIME, which, as it is -more even in grain, more easily cut in any direction than most woods, -is greatly used by carvers and pattern-makers (_i.e._, those who make -wooden patterns of wheels, or lathes, or machinery, which are to be cast -in metal). [The pattern is pressed into damp sand, and then removed, and -the melted metal is then poured into the impression thus made. If the -sand is too wet, the process will not only fail, but the hot metal will -be scattered on all sides, inflicting dreadful burns and injuries; but -with care, the young amateur may make castings in tin or lead, as will be -explained by and by.] Even with a penknife alone, very pretty ornaments -may be carved from the wood of the lime, and also from that which follows. - -WILLOW.—This is even softer than the last, and will plane into long, -thin shavings, which are made into hats. (Once on a time I should have -said “_and bonnets_,” but in these days no one would recognise such -articles. They are fast fading out of existence; but I think quite as -much sound sense used to be found under them as is now found under the -very inefficient substitutes worn by ladies of the present day.) This -wood will, of course, turn very easily, but requires very keen tools. In -fact, _sharp_ gouges and chisels are invariably necessary for soft wood -turning. Get some dry willow by all means, if you can. - -The last wood of English growth which the young mechanic is likely to -meet with is the thorn. This grows to a tolerably large size, and -is hard, close-grained, white, and altogether a good and serviceable -wood. It will make capital chucks, taking a clean screw-thread, is -easily procured, and is therefore strongly recommended to the notice -of the young mechanic. The woods above named, except box, are all to -be considered _soft_ woods, and will work with gouge and chisel; but -box, thorn, elder, and one or two of the more close-grained, will turn -pretty well, and can be smoothly hollowed out, with hard wood tools held -horizontally upon the rest. - - -HARD WOODS. - -All those woods, properly called _hard_, including the best box, are -of foreign growth, mostly coming from the Tropics. I do not know why -they should be so much harder than those of temperate climes, but so it -is. There are, however, woods in New Zealand, of which the temperature -is similar to that of our own country, which are also exceedingly hard -and difficult to work. A very large number of foreign woods are yearly -brought to England in logs or billets or planks, some of very large size, -and all of great weight. They are mostly liable to one defect, viz., -rottenness of the core or heart, which limits the size of the pieces -which can be cut from them. They can all be procured from the London -lathe and tool shops, and there are also dealers in these woods (Jacques -of Covent Garden, Mundy & Berrie of Bunhill Row, and some others). It is -almost impossible to procure them in the country, but rosewood, ebony, -kingwood, &c., may be sometimes had in such small pieces as the young -mechanic may require, at the cabinetmakers’. Among the most useful are— - -EBONY, of which there are two or three kinds, some harder and more -close-grained and blacker than others, and one which is called green -ebony, which is like lignum-vitæ (an English wood, but which grows to a -larger size abroad; indeed, many so called English woods are not really -so, but have been brought from other countries to be grown here). The -general colour is green, but the veins are rather darker. Bowls and -skittle-balls are made of it. It is not, however, of the same general use -as the black ebony, which is very largely used both for cabinet-work and -turning. - -BLACK EBONY is very close and hard, and, of course, proportionately -heavy. It splits readily, but when chopped, the chips come off more like -charcoal, showing no consistency. This is the kind imported from the -Indies, and especially from Madagascar and Mauritius, and is the best -for all kinds of turned work. Portugal affords another kind, which bears -the same name, but is more brown than black, and softer, less compact in -grain, and generally of less value. Ebony will bear eccentric work, and -all kinds of beautiful carving and ornamentation in the lathe. - -ROSE-WOOD is very commonly used for furniture and turned work. It is a -rich red wood, grained with black. It is not _very_ hard, less so than -ebony, and has more evident grain or fibre. It turns well, and some -pieces are very handsome. - -AFRICAN BLACK-WOOD is in appearance similar to ebony, but it is even more -close and compact, and is the most valuable of all to the ornamental -turner. When this or ebony is set off by being inlaid with ivory, or -even holly, it is very lovely in its intense and brilliant blackness. -Either this or ebony is used for black pieces for the chessboard or -draughtboard, though stained boxwood, being less costly, is sometimes -made to take its place. - -AFRICAN CAM-WOOD is a very beautiful material when first cut. Its -rich red tint is diversified with the most brilliant yellow streaks. -Unfortunately, however, these are not lasting. Exposed to the air, they -gradually become darker, until they become red like the rest of the wood. -This material, however, has a fine, close grain, is a genuine _hard_ -wood, and of general use to the turner for ornamental articles of various -kinds. - -TULIP-WOOD is not very hard. Cut across the log, the appearance is fine, -owing to the rings of growth being wavy and irregular, in dark and light -red alternations, that reminds one of the flower after which it is -called. This tree, indeed, which grows to a large size, bears flowers -similar to those of our gardens imported from Holland, which grow upon -short perpendicular stems. The centre or core of tulip-wood is generally -rotten. It sucks up a good deal of polish before the grain shows out -brightly and strongly, from being less hard and more fibrous than many -others named above. - -PARTRIDGE-WOOD is a nice, hard, and very pretty wood, rather dark or -gray. The fibres seem to run both ways, giving a mottled appearance when -turned. - -CORAL-WOOD is bright red, hard, and close in grain, well suited for red -chessmen, where that colour is preferred to black. It looks very handsome -in the midst of other coloured specimens; otherwise, like all material -of one tint and free from veined lines, there is too much uniformity -of appearance to make it pleasing to the eye of one who is gifted with -appreciation of colour. - -It is not necessary for me to go in order through a long list of foreign -woods. The very young mechanic, unless living in London, will seldom meet -with many of them; and a very good selection for the advanced turner will -be composed of the following:— - -BLACK EBONY. - -COCOA or COCUS, which is not the cocoa-nut tree, this being a palm, the -wood of which is stringy like a fern or a cane; whereas, cocoa or cocus -is firm, hard, and excellent. - -BLACK-WOOD, which cuts finely with tools for eccentric work. - -KING-WOOD, a good and useful wood, something akin in appearance to -rosewood. - -SATIN-WOOD, pale yellow grain, like watered silk, turns very well, but is -by no means hard; there is also a red satinwood. - -ROSE-WOOD, already described; it loses colour after exposure, and is most -beautiful newly cut. - -If the above are added to the most useful of the English woods described -above, it will scarcely be worth while to add to them except as -_specimens_. It is, however, very interesting to collect and arrange -these, and it is an employment well worthy of the attention of the -young mechanic. Thin slices cut across the grain, and sometimes, or in -addition, slices cut with the grain, should be arranged in order after -being trimmed to shape (round, square, or triangular, or even six-sided). -They should be very carefully polished to bring up the grain, and -labelled with the common and Latin (or botanical) name. The country from -which procured, with short notes relative to the size and general growth -of the tree, should be added. This will compel inquiry, and a great deal -of information will be thus gained and stored up. A similar collection of -English woods may be made, and, of course, with much greater ease. - -It will be observed that I have said nothing of the pines, deal, and -larch. They are extensively turned in the lathe, the greater part -of the common painted furniture being made therefrom; but deal is, -nevertheless, not a turning wood. It splits easily, has an open grain, -with fibres loosely connected, and although it can be cut into mouldings -with sharp chisels and gouges, it generally needs a little rubbing with -Dutch rush, fish-skin, or glass-paper; after which, a handful of its own -shavings held against it as it revolves rapidly in the lathe, is the best -polisher. Of course, however, it may be varnished, and of late years it -has become fashionable, when thus finished, for bedroom furniture. It -is, however, in this case generally improved and embellished, by having -thin strips of coloured woods inlaid in its surface. It is useless for -_hollow_ work; and wood that cannot be hollowed out satisfactorily, is -not to be classed among those suitable for the turner. - -Whenever you have time to spare, and are not inclined to turn, yet -feel disposed to wander into your workshop, it is a good plan to trim -and prepare pieces of wood for the lathe. You need a chopping-block, -which is the end of a stick of timber sawn evenly across, and stood -up in some out-of-the-way corner where chips will not be much in the -way, and a light axe or adze, which latter is said to be the best. It -is called the bassoohlah or Indian adze, but I never had one, nor ever -saw it mentioned, except in one very excellent book by the late Charles -Holtzappffel of London, who, indeed, keeps these tools. But a light axe -is easily obtained, and will do very well. Take care to saw the pieces -off truly square—I mean straight across the log, and not slanting either -way. Cut some from your evergreen oak, or beech, or elm, for chucks, -remembering to have length for the mandrel screw, beyond what you will -probably need for hollowing out, to take the pieces to be turned. Cut -some longer than others, and from larger or smaller pieces; from 2-inch -diameter to 4, which is a useful general size. But your lathe of 5-inch -centre will take chucks or work of nearly 10 inches, so you can cut some -few pieces rather larger. Probably, your only work of 6 to 9 inches -diameter will be an occasional bread-platter, or a stand of some sort; -your general work will be much less. Besides chucks, of which the number -is in time very great, you will be constantly wanting tool-handles. Cut -some for these, and placing one end on the chopping-block, trim them to -something like the required size, but a good deal larger round than you -think necessary, because you will find that the size will deceive you -frequently. - -[Illustration: Fig. 43.] - -For finally trimming up short pieces, a peculiar knife is used by the -lathe and tool makers; and when you can spare the money you should get -one, as you will find it easy to use, and it will save you many a cut -from the axe. In fact, I never advise _very_ young mechanics to make use -of the latter tool. It requires practice, strength, and a good deal of -skill to use it well; and nothing is more easy than to lop off the end -of a finger or thumb, and, unfortunately, nothing is more difficult than -to repair the damage. The paring-knife for short thick pieces mentioned -above, is made like D, Fig. 43. It consists of a long and curved handle, -turned up at one end to fit under a staple, E, with a cross piece of wood -for the hand at the other end, and a broad strong blade with one bevel -in the middle—(by one bevel I mean, that the edge is not like that of an -axe, but like that of a carpenter’s chisel, the bevel or sloping part -being outside). C is the piece of wood to be pared, A the bottom board or -platform, B a block fastened to it, and made on a slope to prevent the -tendency of the wood to slip away from the knife. The whole of this may -be screwed down to the bench, or to a heavy stool when in use. The hook -and ferule should not be made so large and loose as in the drawing, and -a better joint is that of an ordinary hinge. If made loosely, the blade -twists about too much from side to side, escaping from the wood. There is -no danger to the fingers from this useful tool, which the young mechanic -should add to his workshop as soon as he can. - -Another useful and easily-constructed apparatus for the preparation of -long pieces is the shave-stool, used by coopers and chairmakers to hold -the pieces securely while they are being shaped by the double-handled -shave or drawknife, as it is often called, a tool omitted from our list, -but very useful all the same. This is sketched at B, Fig. 43. It is often -very roughly made, the chief necessity being that it shall be strong. It -answers also for a sawing-stool. Upon the stool or bench, A, is fixed -a sloping block, B. A swinging frame, C, is hinged or pivoted at D, so -that if the lower part is pushed back from left to right, the upper -cross-bar, E, will come forward and almost touch the highest part of the -sloping block, B, so that any piece of wood, such as F, will thereby -be pinched and held tightly between the rail, E, and the block. The -workman sits astride of the stool at A, facing the block, and his feet -are placed on the bar C. When he wishes to hold the wood which is to be -shaved by the drawknife C, he presses _from_ him with his feet the lower -part of the frame, and he can instantly loosen the wood by drawing his -feet towards him. The movement is made in a moment, and the wood shifted -round as required, and alternately turned about and held tight, while -the drawknife is used almost ceaselessly. A very few minutes generally -suffices thus to pare down a rough piece for the lathe. The cross-bar, -E, should be tolerably strong, and is better if not rounded very nicely, -as the edges help to hold the wood. The latter is sure not to slip away, -because the pull of the drawknife tends to draw it up higher on the slope -of the block, which pulls it into a still narrower opening. Nothing can -exceed the ease with which this appliance is used, and the rapidity with -which the required operation can be carried on. No wood-turner’s shop -should be without one. - - -ORDER AND ARRANGEMENT OF TOOLS. - -[Illustration: Fig. 44.] - -I must say a word or two as to neatness and order, especially in the -arrangement of tools and appliances for the lathe. Whether you have a -dozen tools or a hundred, always put them in the _same place_, so that -any particular article can be found instantly, no time being wasted -hunting up and down, or examining a long row of tools for the one -required at that particular time. Turning tools, moreover, should be -kept distinct from those used for carpentry, and in a special rack by -themselves. The best tool-rack, I think, which can be made, is one like -Fig. 44. This may be made of deal, but the pieces between the holes are -thus liable to get split off, and beech or ash is therefore preferable. -The whole frame is made to be screwed to the wall; or, if the latter is -damp, the frame should be first screwed to a board covered with baize, -and this, in turn, fixed to the wall. Thus arranged, it will have a very -neat appearance, and the tools being kept dry, will remain generally -free from rust. They should, nevertheless, be carefully looked over once -a week and wiped, when those requiring to be ground should be subjected -to that operation, and thus be ready for future use when required. They -are bad workmen who allow blunt or damaged tools to accumulate, instead -of at once setting them in order. The horizontal bars are bored with -holes by means of a centrebit. The holes must be arranged as to size by -the measurement of the _ferules_ of the tool handles, some being larger -and some smaller, so that when the tool is placed in any hole, the handle -will drop in to the depth of the ferule and fit. Thus the tools will -all stand upright, instead of leaning from one side or the other. After -the holes are made, a piece is cut out (see fig. B) at the front edge, -because the blades of some tools are wider than the ferules, and, in -addition, if this were not done, the different tool-rails must be as far -apart as the whole length of the tool (handle and all included), to allow -of the latter being lifted sufficiently high to drop into the holes. - -The strips for the holes should be about 2 inches wide, the lower one, -for the larger chisels and gouges, rather wider than the upper ones. -Sometimes these tool-racks are fitted up inside a cabinet, whose doors -have similar racks; thus all can be shut in out of the reach of dust -and dirt. Holtzappffel, the great lathemaker of London, fits up such -cabinets complete in oak or mahogany, all the tools being handled in -hard wood and turned to one pattern. The cost, however, £5 and upwards, -renders such less desirable to the young mechanic, who can rig up a -common tool-rack, which will serve his purpose equally well. It is also -far more satisfactory, in looking round your workshop, to feel that you -have at all events been as little extravagant as possible, for amateurs -get no return for outlay as tradesmen do. - - - - -CHAPTER IX. - - -There is no operation in which the young mechanic is so much at fault as -in that of grinding and setting in order the various tools he has to use. -Nevertheless he will never become either an independent workman or a good -one, if he has to depend upon others for this necessary labour. - -No doubt, to sharpen a tool which is in very bad order is a tedious and -tiresome job; but it is not so wearisome an affair to keep tools in -condition for work, after they have been once thoroughly sharpened by one -who understands how to do it. Never, therefore, use a blunt tool, but -at once go to the hone or grindstone with it, and put it in first-rate -order. Time thus employed is never wasted, but rather saved; and the -result will appear invariably in the work which you are engaged upon. -You must, in the first place, understand precisely what it is you have -to do; and although the following details may be by some considered -more adapted for advanced students than for young mechanics, a little -attention to the explanations will render the matter clear to any boy -of age and intelligence to take in hand, with reasonable prospect of -success, the tools of the carpenter, turner, and fitter. I can only say, -that boys of this generation are wonderfully well off in having these -things explained to them. Twenty years ago young mechanics had to grope -along in the dark, ignorant to a great extent of the _principles_ of -work, and almost equally uninstructed in the practical part of it. - -In Fig. 45 are represented similar angles to those already explained to -you, and you will quickly understand how useful is a little knowledge of -the elements of mathematics. Suppose A to be a tool, the angle of the -point is a right angle, or 90°. B is another of 60° at the point, and I -have drawn a line across to show you that the three sides of this figure -(called a triangle) are equal. So remember that if you want an angle of -60°, you have only to draw a triangle of three equal sides, and each of -these angles will be 60°. Again, I may as well remind you that three -times 60° equals 180°, which is equal to _two right angles_, so we find -here that the three angles of an equal-sided triangle equal two right -angles, and even if the sides are not equal, the same thing is true. For -instance, look at the first tool, across which I have also drawn a line -to make a triangle. The point we know is 90°, and if the sides, _a b_, -are equal (although the third line is _not_ equal to either), the two -small angles are each 45°, _i.e._, 90° between them, so the three angles -again equal 180°. - -[Illustration: Fig. 45.] - -The third tool (which we may suppose a turner’s chisel held _edgewise_) -is shown to have an angle of 30°, and I have added one more which has an -angle of 45°. Now all tools, if _well_ ground, are ground to a certain -known angle, according to the material which they are intended to cut. -Tools intended to cut soft woods, like deal, are ground to an angle of -20° to 30°, like the chisel seen edgewise. I shall have a word to say -presently as to the direction in which such tools are to be held, in -order to make them cut as well as possible. A tool for hard wood is given -next at E. The angle is now at least 40°, and it ranges up to 80°, giving -a stronger, thicker edge, but not so keen a one. We have, therefore, more -of a scraping tool than a cutting one,—at least, in the way it is usually -held. Then we come to the tools with which iron is turned and steel also. -Fig. F is one of these, and the usual angle is 60°, and thence it ranges -to 90°. Thus you see, advancing from soft wood tools to those for hard -wood, and thence to a substance still harder, we have increased the angle -of the edge, beginning at 30° and ending with 80° or 90°. But now we come -to a material which is harder than wood and not so hard as iron, yet we -use tools with an angle of 90°, which is still greater, and 70° is the -least angle ever used for this metal. - -Experience only has taught the proper angle for tools, and it is found, -that if brass and gun-metal are turned with tools of a less angle -than 70°, they only catch into the material, and do not work at all -satisfactorily. You can, however, _scrape_ brass, as a finish, with the -thin edge of a common chisel; but then the tool is held so as to scrape -very lightly and polish; and its edge will not remain many minutes, -unless the maker (intending it to be so used) has made it much harder -than he would make it for soft wood cutting. - -If you buy your tools at any _good_ shop, you will find that they are -already ground to nearly the angles named, and when you re-grind them, -you must endeavour to keep them to the same. The _bevel_, as it is -called, of many tools need not be ground at all, as they may be sharpened -solely by rubbing the upper face on a hone, or grinding it, holding it -so that the stone shall act equally on all parts of it. If, however, the -tool should become notched, you must grind the bevel of it, and then you -must try and keep the intended angle. One tool, however, or rather one -pair of tools, viz., turning-gouges and chisels, are very seldom ground -with a sufficiently long bevel when they first come from the maker. The -usual shape of the edge is like G, whereas the angle should be much less, -as seen at H. This you must correct when you first grind the tools for -use, and keep the same long bevel and small angle of edge continually -afterwards, for you will never make good work on soft wood if your -chisels and gouges are ground with too short a bevel. - -I must also guard you against another common error, which, however, is -very difficult to avoid at first, and only long practice will enable -you entirely to overcome it. I, is the chisel (held edgewise as before) -ground as it ought to be; K is the same tool ground as it generally is -by young hands, or, even if it is correctly formed at the grindstone, -one or two applications to the oilstone almost invariably round it off -as shown. The bevel of _all_ tools must be kept quite flat and even, and -when the tool is afterwards rubbed on the oilstone to give a finish to -the edge, another flat, even bevel should be made. In the same figure at -L is an exaggerated view of the chisel, with its first long bevel formed -at the grindstone, and the second very small bright bevel seen at the -extreme edge of all such tools when they have been set upon the oilstone. -This second bevel, slight as it is, you will at once understand makes the -angle of the edge a little larger, therefore you must allow for it, and -grind a little keener edge than you really require. - -Now, all this is very simple and easy to understand, and when you have -mastered this much, you will be in a fair way to understand more. The -second part of the subject, nevertheless, requires very close attention, -and very likely may not become quite clear to you when explained. I shall -therefore draw a line here, and make this lesson a special paragraph, -which you can look back to some other day, when you are grown from -a boy-mechanic to a man, and have had more experience in cutting and -turning wood and metal. - -The tools above described have their cutting edges formed by the meeting -of two planes at a given angle,—these planes being the flat bevels (or -the flat top and one bevel) formed by the grindstone. But in some tools -three planes meet to form an edge instead of two, and the angle of -the cutting edge is not the same as that of either of these, although -it depends upon them, and can be nicely calculated. This calculation, -however, requires a knowledge of some higher branches of mathematics than -the young mechanic is supposed to be acquainted with, and therefore a -table is added instead, by which, when the angles of two of these planes -are known, the third may be at once seen, which last determines, of -course, the angle of the edge. - -As an example, take the graver, of which you will find a drawing among -the other tools, but which I give again in this place. M, Fig. 45, is -the tool, looking at the face or bevel which has been ground upon it, -making a lozenge-shape or diamond. But this face is a _third plane_, and -the cutting edges, _a_ and _b_, depend for their angles upon all three -of these. Now, for iron we want an angle of 60°. How are we to make -the edges, _a b_, of that exact size? The bar is first of all square -in section, like N, which would be its shape before the third face or -bevel is ground, and all the angles are now right angles of 90° each. -But instead of this, we want two of them 60°, the other two being of no -importance. We simply proceed thus:—Determine which angle is to become -the point of the tool (it is no matter in the present case, as all are -alike), then grind away underneath till the new bevel forms an angle of -45° with the back (by which I mean the edge which runs along from the -sharp point towards the handle—the edge _x_ in fig. O). Trigonometry -enables us to find out that an angle of 45° is the one required, but you -will find it in the table annexed to this chapter, and an explanation of -this table is also given to enable you to use it easily. Thus ground, the -edges _a b_ of fig. O will be each formed of two planes meeting at an -angle of 60°. You can make a gauge of card or tin, P, to work by, of the -required angle. - -[Illustration: Fig. 46.] - -[Illustration: Fig. 47.] - -In order to understand the use of this table, it is necessary to give -names to the several angles of a tool. That upon the front or face of -the tool, as A of the point-tool, is called the plan-angle; that made -by the upper surface and the front edge, as B (_a_, being the angle in -question), is called the section angle, because, if you were to saw -right through the central line lengthwise, this is the angle that would -appear at the point, viewing it sideways. Now, if we look at C, Fig. 47, -we shall be able to understand how the front line, _b c_, is obtained, -which constitutes one side of the section angle of a tool. It results -from the meeting of the two diamond-shaped planes at the sides formed -by the grindstone, but is dependent also on the plan-angle. These two -side-planes are to be generally ground at an angle of about 3° from the -vertical, which is to give the clearance of the tool if held in a fixed -position, as in the tool-holder of a slide-rest, the tool being supposed -horizontal. This is in accordance with what I have before told you, viz., -that the cutting edge should be presented to the work at the smallest -possible angle, 3° being very small indeed. This angle is generally -measured by placing the side ground in contact with a cone of wood or -metal, turned to an angle of 3°, such as D,—_k_ being a tool the front -of which is evidently 3°; or a piece of tin, _l_, cut to the same angle, -and stood on its edge, will answer the same purpose. By 3°, I mean an -angle of 3° measured on the circumference of a circle, as I have already -explained in a former page, such angle being of course at the centre -of the circle where the lines drawn from the several degrees on the -circumference meet. - -Now, when you have ground these two surfaces, the line _b c_ of B (or -C) will have a certain slope or inclination depending on the plan-angle -of the point. The exact inclination of it may be therefore said to be -accidental; but, whatever it is, it becomes of great importance in the -final result, being one side of the angle which will give any particular -angle of cutting edge. And here the table comes into use:—Suppose I wish -to have an edge of 60°, for cutting iron. Measure the _plan_-angle,—say -it is 90°, which is that of the graver; then, on the table, under the -words “plan angle,” you will see 90°, and opposite, above 60° of “cutting -edges,” you will see 45°. You have only to grind back the upper face of -the tool, until it makes an angle of 45° (section angle) with the front -edge or line, _b c_, and the edges _x x_ will be angles of 60°. Or take -the tool E, of which the plan angle is 120°, and suppose you want cutting -edges of 80°, for brass, opposite 120°, and above 80°, is 78° 5″. Grind -back the top face to an angle of 78° 5″ (or 78½) with the point line, and -it is done. - -Until you have practically proved it, you can have no idea of the vast -importance of having correctly-formed cutting edges, and of placing them -within a hair’s-breadth of the proper position. But it is in slide-rest -work especially, and in cutting metal with tools held rigidly in one -position, that this is of such paramount importance. It makes all the -difference between cutting off a clean shaving, and tearing from the -material by main force a quantity of disjointed particles, the latter -process leaving a rough unfinished surface, the former producing one -as smooth and polished as a sheet of glass; and the advantage of this -short table is, that you can at any time shape your own tools for the -particular work in hand. - -After you have had some practice in turning, you should certainly learn -to shape your tools from square bars of steel, worn files, and broken -steel tools of various kinds; and before you have arrived at sufficient -dexterity to do this entirely by yourself, you will get them roughly -shaped for you by the blacksmith, and then with grindstone and file you -will further perfect the angles for use. Steel does not require, and -must on no account be subjected to, a white heat, or you will spoil it -hopelessly; and you can always heat it in a common fire, or in the little -stove that I shall describe in a subsequent chapter, to a temperature -that will allow you to bend it into any required form with the hammer and -anvil—a bright red being the utmost heat it must be brought to. - - -POSITION OF CUTTING TOOLS. - -We must now consider the mode of applying the edge of a tool to the work, -so as to produce the best effect. First, we will consider the case of a -gouge and chisel acting upon soft wood. - -[Illustration: Fig. 48.] - -In Fig. 48, A represents a piece of wood in the lathe, as you would see -it if you stood at one end of it, and a chisel is being held against -it. The arrow shows the direction in which the wood is supposed to be -revolving. Held thus, the chisel would scrape, and its edge would be -carried off at once; it could not possibly cut. But, held as at B, -it would cut off a clean and continuous shaving as the wood revolved -against it, and this shaving would slide off along the upper face, _b_, -of the tool, so that you can see that this face ought to offer the least -possible resistance to it. The tool acts, in fact, like a very thin, -sharp wedge, which divides the material by pressure, which has to be -great or slight according as the edge is sharp and thin or the contrary. -Now, if you again look at A, you will see that this wedge-like action -cannot take place, so that the tool is in its worst possible position. - -Between the two positions, however, here shown, are several others at -a greater or less angle to the surface of the wood; but the smallest -possible angle it can make is the best, so long as the thickness of -shaving removed will suffice for your purpose. This rule holds good -with all tools, whether carpenters’ or turners’, which are made with -sharp-cutting edges. Care must be taken, however, that the lower face -of the tool does not rub against the work, which, again, it is evident, -limits to a given degree the angle at which the cutting edge is to be -applied to the work. - -We now pass on to C, which represents the ordinary tool for turning iron, -held flat upon the rest, the position it usually occupies. We see at once -that in this case also we have a scraping tool only, and that, although -the angle of the edge is far greater than that of the chisel, it must -soon be ground off by the action of the metal to which it is applied, or -of the hard wood, which is also cut in this way. But with this form of -tool we shall find it impossible to apply it so as to cut in the best -way; because if we lower the handle, as we did that of the chisel, the -part below the edge will rub against the work, while the edge itself -will be moved out of contact with it. Thus we are obliged to hold the -tool in the position first shown; but we may therefore conclude that the -_tool itself is a badly formed one_ for the intended purpose; and so it -is, although you will see it in almost every workshop in the kingdom. -Let us see what can be done to improve it. At D, I have represented the -same tool, but the blackened part shows what has been filed away from the -upper face, and the dotted lines show that, when this has been done, a -tool is made very similar to the chisel for wood, and that it is also now -in a good position for _cutting_ (_not scraping_), although it is still -held horizontally upon the rest. Shavings of iron curl off the upper face -of this, as wood shavings curl off upon a chisel. - -If the angle, however, is too small, the edge will soon be broken off, -and the tool will dig into the work; hence the necessity of knowing -at what angle a tool ought to be ground to cut any particular metal -successfully. - -Such a tool as the last named, which is intended only to cut with the -front edge, and which is represented in E, is called a single-edged one, -because it only cuts in one direction, but many others are double-edged, -cutting the shaving at once on the flat and edge—that is, paring it off -from the material below and also from the side. For instance, F is a -cylinder of iron, from which a shaving is supposed to be in process -of being cut. It has to be removed from the shoulder to which it is -represented as still adhering, and also from the flat surface, _e b_, -around which it was, as it were, once coiled. But this requires two -cutting edges, both acting at the same time, but in different directions; -and good mechanics therefore so form the tools, and so use them, as to -cut in both directions, which leaves the work beautifully smooth and even. - -These tools are mostly used in the slide-rest, where their true position, -once determined, can be accurately maintained; and it is, perhaps, only -with the slide-rest that perfect work can be done. There is, however, -no reason why you should not use tools of all kinds intelligently, and -understand exactly how they should be formed, and how held. Suppose you -have a tool correctly made by the aid of the table of tool angles already -explained, still looking at fig. F, you can see that the smaller part of -the roller is that which is to be left finished, and that it ought to -be quite smooth, but the shoulder at _a_ is not of the same degree of -importance. A tool fit for such work would evidently be shaped on its -_plan-angle_ or face, like H in fig. C or I; and, if held as seen, both -edges would be brought into action at the same time, as will be at once -evident on inspection. In practice, however, the two edges would not be -allowed to touch for their whole length, or the angle on the right would -leave a scratch upon the finished work; therefore it would be eased off -a little, as at K, L. But this is evidently as nearly as possible the -shape and position to be given to such a tool, and the edge which has to -leave the finished surface should, as it were, _follow_ the other; the -right-hand angle being _just_ and _only just_ kept out of cut. - -The hand-tools you will generally use are the heel-tool, M, held on -the rest as shown, which, you see, brings the edge into cut at the -least possible angle to the work, and the nail-head, which is in fact -a heel-tool of four faces, or, if round, a heel-tool _all edge_, and -which can be rolled over as it gets blunted. To these add the graver, -of which I have already spoken. I have tried to show its position at O, -with the bevel of the face pointed in the direction of the shoulder, and -downwards; but it can be held face upwards also, and in one or two other -positions. Always remember that the cutting edge is to be presented at a -small angle with the work, and you cannot go wrong if the tool is well -formed. The nail-head and heel-tools are single edged, and easily ground -without the table of angles, but the graver is a double-edged tool, -properly speaking, although only one edge may perhaps be used. - -Having explained the principles upon which you have to work as regards -grinding your tools and holding them when in use, I shall merely add a -few remarks as to the action of the grindstone and oilstone, and the -proper way of using them. - -Always let the stone revolve towards you, as if you had to turn it smooth -with the tool you have to sharpen, except when you cannot possibly do so -without cutting grooves in it. Chisels, knives, axes, planes, and all -similar tools with flat edges, are to be ground with the stone running in -that direction, by which means you will avoid giving them a wire edge, -as it is called (_i.e._, a ragged-looking edge), and it will instead be -even and sharp; the filament of metal being, as it were, driven back into -the substance of the tool, instead of drawn away from it. Gouges may be -ground in the same way, but must be rolled about to keep up the form of -edge. It is indeed the easiest way with these to hold them _across_ the -stone, in the same direction as its axis, and then, by rolling them over -backwards and forwards, you can give a very good shape to the edge, which -should run slightly to a point, or rather _tend_ to one. They are never -to be ground square across, like that of the carpenter. - -It is generally necessary to have some sort of rest upon which to lay -the tools during the operation of grinding, but do not trust to special -contrivances for holding them at the precise angle needed; rather trust -to your own skill, which will increase more and more by being severely -exercised. Always remember to grind your tools to a sharper angle than -will be ultimately required, that the final angle may be given by the -oilstone. Of the latter there are many kinds. Nothing probably can -surpass a Turkey stone, if good, but this varies considerably in hardness -and other qualities. There is a very quick-cutting, slightly coarse stone -from Nova Scotia, which is very serviceable, as it does this tedious work -with great rapidity, not, however, putting on the tools a very fine edge, -but one that admirably suits for such as are to be used on metal. With -the rest, a rub or two on Turkey, or Arkansas, or Chorley Forest stone, -will impart a finish. Arkansas stone, however, may be had coarse as well -as fine; it is much liked by some, but I prefer the Nova Scotia, as it -cuts more keenly, and even with the sharpest stone, setting tools is a -most laborious process. - -The young mechanic will find it very difficult at first to hold the tool -steady, and to move it to and fro upon the oilstone so as not to give it -any rolling movement, by which the edge and bevel would be rounded, as I -before explained, which would in effect enlarge the angle of the cutting -edge, besides preventing it from being held at a sufficiently small angle -to the work to cut effectively. Nothing but practice will overcome this -difficulty; I shall not therefore attempt to describe exactly how the -tool should be held and the sharpening effected, such description being -not only difficult, but, as experience has proved to me, impossible. - - - - -CHAPTER X. - - -We now enter upon the actual work of the lathe, which should be -comparatively easy to understand after the foregoing observations. - -Your raw material having been chopped or shaved into a rough cylindrical -form, you have to mount it in the lathe. I may suppose it a piece of -beech for a tool-handle. If you have the cross-chuck, you should use it; -if not, you may use the prong instead. In either case, centre the wood as -truly as you can, so that, when the rest is fixed near it, the piece may -not be much farther from it, as it revolves, in one place than another. -Mind and screw down the back poppit tightly upon the lathe-bed, and also -the rest, putting the latter as near the work as you can without touching -it. Now set the lathe in motion,—this is tolerably easy, but to keep it -in motion will probably not be easy at all. It is one of those operations -which require practice, because while your leg is at work upon the -treadle, your body must be firm and still, so that you feel yourself free -to use the tools without giving much attention to what your leg is doing. -After a while you will do this with perfect ease. The wood is, of course, -to rotate towards you, and the surface will come in contact with the -edge of the tool as the latter is _held tightly down on the rest_. Now, -this is, after all, the real difficulty, for every projection striking -the tool tends to jerk it off the rest, and this has to be resisted with -some force. There is, however, this advantage in hand-tools, viz., that -they may be held rigidly yet be allowed some slight play, according to -the peculiar exigencies of the work; and at first you will save the tool -by allowing it to yield slightly until the roughest part has been cut -away. Afterwards, there is to be no movement except that required to make -it follow the curves or level parts of the work. Do your best first to -produce a cylinder, _i.e._, a straight, even piece of wood, as long as -the required handle, and as large round as the largest part proposed to -be given it. It is the best plan at first to copy a well-shaped handle, -and to turn as many as you want of that size exactly to the same pattern. -This will give you such an amount of practice in copying form, as will -stand you in good stead in after days; for it is not easy at first to -turn even two things exactly to pattern and to _size_. - -You must not expect to be able to run your tools along the work like a -professional or old hand at the lathe; you must do the best you can. Hold -the handle in the right hand, and with the left grasp both rest and tool -together, and you will hold it firmly. Then you _ought_ to run it along -right or left at the right speed and the right angle, but you will be -unable to do so yet;—never mind. Remember the _principle_ I have laid -down as to the position and angles of cutting tools, and trust to time -and perseverance to make you a good workman. - -The gouge is the easiest and best tool to use at first; and you can do a -fair amount of _smooth_ work with it if you know how, although smoothing -and levelling is the special work of the chisel. The gouge, however, is -used for all sorts of curves and hollows, and though the actual point -will only turn a groove if held still, the _side_ of the cutting part -will, if the tool is steadily advanced, turn very fair surfaces indeed. -I strongly advise practice with this tool before attempting to use any -other. Your early work is of little importance, and you may make up your -mind to cut several pieces into shavings and chips without very grand -success, even though you use a chisel; so I repeat, stick to the gouge -only for some time, until you can use it towards left or right, and with -either hand grasping the handle. - -With the chisel, far more care is required than with the last named. -It is altogether a more difficult tool to use. Its position may be -described as follows, but practice alone will render its use easy. Lay -it first flat on the rest as you would the gouge, and let it point -upwards at a similar angle, until it also is in the position the gouge -would take, ready to cut the piece of wood in the lathe, already turned -to the cylindrical form by the latter tool. You will find one point or -angle of the edge, the sharpest, reach the wood before the other, and -will see at once that this would be liable to catch in, if the lathe -were in motion—and so it would. I shall suppose that this sharpest angle -is on the right-hand side as it lies flat on the rest, and against the -wood. Raise that angle so that the tool lies a little edgewise on the -rest instead of quite flat, when the angle of the tool that is highest -on the wood will be also raised off it; the lower angle and remainder of -the edge still being in contact with it. This is its proper position, -with the upper angle out of contact with the work. You may turn it over -so that the keenest angle is the lower one, but then you must raise the -other, which is now the upper one, for under no circumstances must the -one that is uppermost touch the wood. The chisel, therefore, never lies -flat on the rest or on the work, but always slightly raised to clear the -upper point, and in this position you have to keep it, making it descend -into hollows, and rise over mouldings, and cut level places, almost -without stopping an instant; and for wood, especially soft wood, the -lathe is always itself to be run at a very high speed, by putting the -cord on the largest part of the fly-wheel and smallest part of the pulley. - -To return to the supposed tool-handle. Having turned a cylinder, begin -at the ferule, which you must cut off a brass or iron tube, or, which is -easier, buy by the dozen or by the pound ready cut. You will want them -three-quarters of an inch for your largest tools, and about three-eighths -for the smallest, with some of half an inch, and you can then bore your -tool-rack exactly true with centrebits of these sizes. Turn the place -down for the ferule, and take care that you make a tight fit. Gauge with -the callipers first of all, and turn almost to size, then try it on once -or twice until it fits exactly. - -If you use the cross-chuck, you have this one great advantage—you can -take out your work to put on the ferule, and replace it exactly as it was -before, and it will continue to run true. As, however, the piece in the -present case is but partially turned, it can be replaced with sufficient -accuracy upon the prong-chuck, especially if you mark the side of the -chuck, and of the piece of wood, and take care to replace them in the -same relative position. You must now try with gouge and chisel to imitate -the pattern handle, remembering always to work downwards from right and -left into the various hollows—(you cannot cut the fibres neatly if you -try to go up-hill); and where the two cuts meet in the hollows, you must -do your best not to leave the least ridge or mark. You will be sure to -need a little glasscloth to finish off your work, but do without it as -much as possible, because it spoils the shape of mouldings, rubbing off -the sharp angles, which in many cases add beauty to the work. If the -piece of wood is longer than necessary, cut it off with the chisel. In -any case, you must cut off a piece at the chuck end; and this being the -end of the handle which you will hold in your hand, the ferule being at -the end next to the back poppit, you will cut it off neatly with the -chisel in finishing it to the required shape. - -You would hardly suppose it possible to turn off the end of a piece -squarely and accurately with the gouge, but it is a good tool for the -purpose. You must lay it on its side upon the rest, so that its back or -bevel rests flat against the end of the piece from which the superfluous -wood is to be taken; the edge or point of the tool is then allowed to cut -the work by a slight movement of the handle. You can only do it in this -way, with the bevel against the piece from which the cut is to be taken. -Turned over to its usual position, it will hitch in and spoil the work -in a moment. In the same way you can face up a bread-platter or similar -flat work; but such articles as these are not mounted between centres, -but screwed upon the taper screw-chuck or the flat plate with the -screw-holes, so that you can get to the face of them. At first, however, -until the work gets tolerably level, you may bring up the back-centre, -which will prevent the taper screw of the chuck from being accidentally -bent; and when all the rough part is cut away, and the rim turned down, -you can remove the back-centre to finish the facing up. In this work, -however, the back and face do not need much turning, because the platter -is turned from plank wood, planed up truly on each side, and cut roughly -into the form of a circle. If accurately planed, it will run true at -once, and the small amount of facing may be done with the gouge held as -directed. Afterwards it may be necessary to take a light _scrape_ with a -_carpenter’s_ chisel, which answers well for this. Then finish up with -glass or sand paper. Take care to make a neat moulding to the edge, which -will be about an inch thick, and will therefore look very heavy unless -turned off so as to thin it down. A platter is a very good and useful -work for a beginner. - -In turning a platter you will certainly learn one lesson in mechanics. -You will find that it is very hard work to turn anything that is larger -than the pulley of your lathe, and you will only be able to take a very -light cut. Probably you will find it the easiest plan to set the lathe -in rapid movement, and apply the turning-tool only for an instant, and -then to remove it until the work has recovered its impetus, thus cutting -it, as it were, by repeated brief applications of the tool, instead of by -one continuous cut. I do not mean that the tool is to be removed from -the rest, but only eased off for a second from the work. If the latter is -very large, and the pulley on the mandrel much less in size, you can only -work in this way, finishing with a very light cut. There is a tool for -the face of such flat works, called a broad. It is like a broad chisel -with the end turned up at right angles to the side, only the edge is a -bevelled one and thick. They work well in hands accustomed to them, but -the gouge and chisel are sufficient for your present need. - -I shall sketch here (Fig. 49) one or two articles not requiring to -be much hollowed out, which will help you to decide upon such work -as is suitable to a young mechanic desiring, by steady practice and -application, to become a proficient at the lathe, and as soft-wood -turning will teach you more than that in hard wood, I shall direct all -the following to be made of it by gouge and chisel alone. - -[Illustration: Fig. 49.] - -These examples are not given as specimens of the rich work which can be -done in the lathe, but as easy examples of elementary turning. No. 1 is a -stand for an urn or hot water jug, and a slight recess may be made in the -upper surface, in which a piece of cloth, or carpet, or oilcloth can be -glued, which will make a neat finish. No. 2 is a bread-platter, showing -how a little neat moulding takes away the clumsy appearance of the thick -board necessary for this purpose. No. 3 is a candlestick. The lower part -or stand is to be turned from a separate piece of thick board screwed -upon the taper-screw chuck. While it is in the lathe, the hole must be -made in the centre (or marked, if the piece is not very thick) by holding -a pointed tool a little on one side of the centre, so as to describe a -circle of the requisite size. Into this will be fitted a tenon, fig. 3 B, -which is turned on the pedestal, and which is to be glued into its place. -By and by you will learn how to cut a screw upon such a tenon, which is a -far more satisfactory method of proceeding; at present glue will answer -just as well. You can make the upper part separate, forming the junction -at the line C (Fig. 49, No. 3), if you prefer it, or if your wood is not -long enough; but as you will not hollow out the top, you may as well let -it be cut out of one piece with the pedestal. Turn the top quite level, -drive in a piece of stout wire, and point the end of it. Cut out a round -piece of tin to fit, and make a hole in the middle of it to let the wire -through; drop it over the point, and let it rest on the candlestick; a -wax candle can be spiked upon the wire, and will stand firm. - -Figs. 7 and 8 are drawings of tool-handles. These are the best shape to -grasp in the hand, and they look neat in the tool-rack. Tool-handles -with a number of mouldings, are not only absurd, but are uncomfortable -to hold, and not at all suited to their intended purpose. 9 and 10 are -other forms of mouldings, and are given merely to show how angular and -rounded forms should be combined to produce a good effect. If these were -to be made in hard wood, they might be turned with beading and moulding -tools similar to those at A, B, C, D of this figure; such tools are -bevelled only on one side, and being held flat upon the rest, cut the -curves and hollows rapidly, and clean. Sometimes a number of these are -arranged side by side, so as together to make up the outline of the -intended moulding, and being held in position by a handle designed for -the purpose, are presented all at once to the work as it revolves. In -other cases, a flat plate of steel is filed into shape, and bevelled to -form a compound moulding tool. Of course, such contrivances greatly help -the turner, especially if he has to turn a number of articles of exactly -the same pattern, such as the pawns of a set of chessmen, or a set of -draughtsmen; but none of these tools answer upon soft wood, because, as -already explained, tools which have to be held horizontally will cut and -tear up the fibres of all woods that are not very hard and compact in -grain. - -Fig. 6 is a profile of a draughtsman, and fig. 6 B shows how they ought -to be made, but for this you cannot use soft wood, and had better make -them of box and ebony, or holly and ebony—(and, by and by, of black-wood -and ivory). A cylinder is first turned, then marked off as shown with -grooves cut by a parting-tool. The pieces are then separated with a fine -saw, and a chuck is hollowed out to fit them so that each can be readily -turned upon the face. The desired mouldings having been made on one side, -the disc is turned over in the chuck, and the other side operated upon in -the same manner. - -It is quite _possible_, you must understand, to cut these out of soft -wood, even pine or deal. We often see boxes of toys, children’s wooden -plates and cups, turned very neatly of this material; but it is not worth -while to use it if you can obtain boxwood. Moreover, box can be stained -black to imitate ebony, and is very often made to serve instead of it. - -Figs. 4 and 5 are ring-stands for the toilette-table—very useful presents -these to mothers, sisters, and, last but not least, lady cousins, and -other young ladies too, perhaps, who are not cousins. These can be made -in a variety of ways, and give great scope for the exercise of your -powers of design. The first is a simple pedestal on a stand, turned quite -smooth in an elegant and simple curve. The stand is also made without -elaborate mouldings, giving altogether a chaste and elegant appearance -to the design. The extremity is tipped with ivory, and an ivory ring -surrounds the bottom of the pedestal. If this is made in plain deal, -and thoroughly well finished and varnished, it will look very well. The -nicest soft English wood, however, for this is certainly yew, some of -which is beautifully fine in grain; and as it will take an excellent -polish, it always looks well; moreover, it can be turned entirely with -gouge and chisel. - -This ring-stand will be made in two parts; the pedestal being separately -turned at one end, a tenon will have to be made as in the case of the -candlestick, and just above it the wood is to be turned off a little -as if you were going to make a larger tenon. Over this a ring of ivory -may be slipped and glued on, and the two can then be turned together. -A carpenter’s chisel will do for the ivory, which will be scraped into -form by it. It may be polished with a little chalk on a moist rag or -flannel. You can buy odds and ends of ivory from the turners in rings and -solid pieces, which will come in for all sorts of decorations, and you -should save all old handles of knives, tooth-brushes, and such like, for -a similar purpose. Both ivory and bone smell very disagreeably when in -process of being turned. To tip such articles with ivory, you can drill a -small hole in the top of the pedestal with great care, and fit the ivory -after being turned into it; or you can, if the work is larger, bore the -ivory and slip it on the wood;—much depends upon the size and nature of -the work. - -The second ring-stand is of rather more elaborate construction. The -baskets are made of little turned pedestals fitted into a round piece of -wood to form the bottom, and into a ring which makes the rim. Baskets of -this form (even apart from the ring-stand) are very neat and useful. - -It is very easy to turn rings of any size. Mount a piece of board in the -lathe on the taper screw chuck—it need not even be cut to a round form; -then determine the size of the proposed ring, and, holding a parting-tool -upon the rest turned round to face the work, mark two circles, and deepen -the cuts, until the ring falls off. Take care that the outer one is cut -through first. The ring thus cut may be afterwards placed upon a cylinder -turned to fit it, and finished upon the outside, and then placed inside -a chuck of wood bored out to suit the work, and neatly rounded off upon -the interior surface. Of course, if you have to make rings of bone or -ivory which are already hollow, you can at once run a mandrel or spindle -of wood or metal through them and subject them to the various operations -required. - -Mandrels, or tapered cylinders of brass or iron, fitted as chucks to the -mandrel of the lathe, are sold on purpose for this work, but a wooden -rod answers just as well, and costs nothing. Turn such a rod a little -tapering, and take care not to drive the work too far upon it, because, -although at first you can safely drive it on very tightly, if it is of -ivory or bone, you will frequently find your ring suddenly split and -open when its thickness has been reduced to the required standard. If a -number of equal rings are required, it is the best plan to turn a hollow -cylinder and then saw off the rings as you are directed to saw off the -draughtsmen. They will, of course, have to be finished in a chuck. - -If you look round any fancy warehouse in which Swiss carvings are sold, -you will see how beautifully soft white pine can be worked in the lathe -by keen tools and clever hands. In Tunbridge, too, many thousands of -soft-wood articles are manufactured yearly, some plain and merely -varnished, and some curiously inlaid with coloured woods, so that you -need not despise such materials as willow and sycamore and the various -pine woods, which are all capable of being made into pretty articles of -one kind or another. The varnish, however, for these is such as to coat -them with a glassy layer which does not sink into the wood. Common rosin -dissolved in turpentine or in linseed oil, kept on the hob so as to get -warm, answers well for these deal articles, and is extensively used where -the slight tinge of yellow is not considered important. There are many -other much paler varnishes for works of greater value, or where the white -wood is to be carefully preserved. Any of these can be had at oil and -colour shops. - -[Illustration: Fig. 50.] - -You will certainly find a difficulty in turning all exactly alike the -little pillars of these baskets. You should turn several at once out of -the same piece, separating them afterwards. Thus your pattern will always -be close to the half-executed copy, which will somewhat assist you. Do -your best in this respect, but be specially careful, at any rate, to -make all exactly the same length. One pillar is shown separate, but you -can design a pattern for yourself. - -Begin by turning a long cylinder; then set off the respective lengths of -the pillars. Turn one complete as a pattern, and set the callipers to -the largest part of it. Then go to work upon a second, using callipers -freely at all parts of it. As these pillars will all be slender, you will -be in great danger of breaking them; therefore use your tools lightly, -taking only a very slight cut. But with all your care you will find it -difficult to turn a row of more than two or three of the size wanted for -such little baskets. I shall therefore show you how to make a support to -fit at the back of the bar you are at work upon to support it against the -pressure of the tool. - -Fig. 50 gives a representation of one or two such supports, which are -often required in turning. The first is the most simple, and is the one -most generally in use, because easy to make and to apply, and it answers -tolerably well. A is merely a piece of wood, about three-quarters of an -inch thick, cut as shown. This is stood up between the lathe-beds, like -C, and fastened with a wedge before and behind. It allows the work in the -lathe to revolve in the notch which is cut in it, as is evident from the -drawing. One, two, or more such may be used if necessary. They must be -carefully adjusted, so as not to bend the piece which is to be turned, -and which is to be just supported, but no more. Where the _back-stay_, -as this contrivance is called, comes in contact with the work, the latter -is to be left of the size it was when this was adjusted to it as long as -possible. It must then be shifted a little, and that part which formerly -rested against it finished. - -B is another simple form of back-stay, capable of nicer adjustment. The -foot is that of a common rest, but if you have not a spare one, any -wooden support is quite as good. Into this fits a turned part of the -upright _x y_,—the upper part, _y_, of this being planed flat. Neither -should be of deal; ash or elm is preferable. Thus the part _x y_ can be -raised and lowered at pleasure in the rest-socket. The top part is made -of a half-inch board, about 2 or 2½ inches wide; a slit is cut in it, -and it is fastened to _x y_ by a short bolt and nut. Thus it is easy to -raise and lower the end of this part, and to put it nearer to, or farther -from, the work in the lathe, against which it can be adjusted with great -nicety. Although there are several forms of back-stay, of more or less -complicated construction, I know of none more generally serviceable than -this last, which the young mechanic can make for himself. The notch -should be lubricated with soap, or, if the blackness is not of importance -(as when this part, which rotates in the notch, has finally to be cut -away), with a mixture of soap and blacklead. This, remember, is always to -be applied to wooden surfaces that are to work easily upon each other. - -It will sometimes happen that you require to bore a hole through a long -piece of wood, as would be the case in making a wooden pipe, flute, -bodkin-case, and many similar articles. To hold these in a chuck only -would be often impossible, because the hole in the chuck would have to be -as deep at least as half the length of the piece to be bored. - -For this kind of work, therefore, and for turning up a point on the -end of a cylinder of iron or steel, like that of your back poppit, -the following contrivance is used, which is called a boring-collar or -cone-plate. It is represented in Fig. 50, D and E. This consists of a -circular plate of metal, three-quarters of an inch thick, turning upon -a large screw or pivot at its centre, by which pivot it is attached to -a short poppit head, fitting between the bearers of the lathe as usual. -There are six or eight conical holes bored round the circular plate, each -of a different size; and these are so arranged as to height, or distance -from the centre, that the top one (being in a perpendicular line passing -through its centre and that of the bolt) is exactly as high as the axis -of the mandrel. Thus, if it is clamped in that position, with the largest -side of the conical holes next the mandrel, a piece of wood might be held -at one end in a chuck, while the other might rest in such hole as was -best suited to its size, not actually passing through it, but resting -in the inside of the conical hole, in which it would rotate almost as -freely and as truly as if it were supported by the ordinary point of the -back poppit. - -Sometimes it may be preferred to allow the end of such a piece of work to -project through the cone-plate, a collar being turned on it to prevent it -from going too far. A tool-handle, for instance, of the pattern before -given, may be beautifully bored in the lathe by allowing the ferule -to rotate in one of the holes of the cone-plate, the shoulder behind -preventing it from going too far. The rest is brought round in front of -the end of the handle, and a hole bored by a drill for wood; or, the -point of a drill is brought against it, while the other end (having had a -slight hole made by a centre-punch for the purpose) is allowed to centre -itself on the point of the back poppit. The screw of the latter is then -advanced, and the drill being prevented from itself revolving either by -being grasped by the hand or a vice, a beautifully straight and even hole -is rapidly made. - -Fig. 50, F, shows the position of the various pieces. The drill is here -kept from rotating by a small spanner, the handle of which comes against -the bed of the lathe. A great deal of work, both in wood and metal, is -always drilled in this way. - -For wood, a small nose-bit, or auger-bit, or one of the American -twist-drills, can be used, and this may be succeeded by a larger, until -the hole will allow of the introduction of a finishing-tool of some -kind, held in the hand. Of course the latter is not necessary in boring -out handles for the tang of a tool, but only in turning boxes for -pencils, needles, or other articles, which require to be neatly finished -inside as well as out; all these are to be bored before the work is cut -free from the superfluous wood out of which it was turned. You can even -use the cross-chuck for this work. - -It matters little, when using the cone-plate, whether you finish -the turning of the outside before or after the boring is done. Very -generally the box or other article is bored first, quite in its rough -state, except that a short piece is turned down to fit into a hole of -the cone-plate; and, keeping the latter in its place all the while, the -wood is turned down and polished before removing it from the lathe. -Sometimes, especially with metal, which is in no danger of splitting, the -cone-plate is removed as soon as the hole has been made and replaced by -the back-centre, the point of which, entering the hole, retains the work -in its place while the outside is being fashioned. This of course insures -the exterior surface being exactly concentric with the inside, which is -often absolutely necessary in parts of machinery; but if wooden articles -are finished in this way, there is great danger of their being split by -the pressure of the back-centre as the work grows thinner and thinner -under the action of the tools. Moreover, it must be remembered that the -back-centre, being itself of a conical form, will injure the form of the -hole in metal by making it wider at the mouth if used in this way, and -sometimes this may be of importance. - -There is a fault in the cone-plate which boys will understand, and men, -too, I imagine. _It costs money!_ Therefore I shall now show you how -to make a substitute, which will cost something under a shilling, if -you do not mind a little trouble; but, if you do, you will never make a -good workman, nor will you be good for much, I fear, in any way! A metal -cone-plate for a 5-inch lathe costs £2 at least. - -I shall suppose you want a cone-plate in which to bore your tool-handles, -for it is not easy to do this with a gimlet, so that the tools, when -inserted, shall stand straight in their handles. If you have a 5-inch -centre lathe, _i.e._, a lathe in which the central line or axis of the -mandrel is 5 inches from the lathe-bed (in which case you can turn -anything nearly 10 inches in diameter), cut out of a piece of beech, 3 -inches thick, a short poppit 3½ inches high, of some such shape as seen -in the fig. G; and in the lower part (which must be cut to fit between -the lathe-bearers, and must be made square at the sides and true, so -that the whole will stand squarely across the lathe-bed), either cut a -mortice, _a_, for a wedge, or bore a hole for a screw, which must have -a plate and nut to fasten under the bed like other poppits. Near the -top, and exactly in the centre, bore a hole to receive the bolt K, -similar to that in the metal cone-plate already described, and which -will be tightened by a nut at the back. This supplies the place of the -short iron poppit, and now you have to contrive something to replace the -circular plate of holes. Cut two or three strips of any tolerably hard -wood, H (beech will answer very well), 6 inches long, half an inch thick, -and 2 inches wide. Cut in these a slot and a round hole, which must be -carefully made with a centrebit. This hole is to be for one of those in -the usual round plate, so be careful in making it. Work thus: Plane up -the piece from wood rather more than the half inch required; draw a line -exactly down the middle of it on both sides _e_, _f_; choose a centrebit -of the size you require; put the point upon this line, about 1½ inches -or more, according to the size of the required hole, and bore steadily a -little way into the wood. Then turn it over, measure carefully so as to -get the precise spot right, and finish from that side. If the centrebit -is sharp, and the wood sound, you will now have a neat round hole. Let -the slot be also cut from both sides of the piece of wood with a sharp -chisel, taking care that the centre of it agrees with the line that you -made for a guide. - -Three or four of these should be made, each with a different sized hole, -or more if required; but you can add new ones at any time. The bolt, K, -is to be made with a large head flat on the under side, and the upper -part, above the screw, is to be square for three-eighths of an inch, and -the slot in the pieces of wood must just fit this squared part. Now, as -this is three-eighths only, and the thickness of the wood is four-eighths -or half an inch, it is plain that the nut will draw, and the head of the -screw clamp this tightly. You can, if you like, however, make the hole -in the poppit square also, and then let the squared part of the screw be -long enough to reach _almost_ entirely through both pieces. Then slip -a washer (an iron plate with a hole in it like L) over the end of the -screw, and fix all with the nut. Thus you have a boring collar with _one_ -hole, and this you can raise or lower the length of the slot so as to get -it exactly the right height, and when it is so arranged, one turn of the -nut at the back will fix it. - -This you will find a very simple form of boring-collar, easy to make, and -of practical use. If you really take all the care you can, and follow -the directions I have given, I do not see how you can possibly fail in -constructing one. You should have a sliding-plate with a hole for each -size of tool-handle ferule used, as you will frequently be making these. - - -HOLLOWING OUT WORK. - -As I have spoken of boring, I will go on to treat now of the general -practice of hollowing out chucks and boxes, and such like. If this is to -be done in soft wood, such as willow, no tool will answer so well as the -hook-tools, of which I have given drawings. But these are very difficult -indeed to use, owing to their tendency to catch in, or take suddenly a -deeper cut than was intended. Nothing but practice will teach exactly how -to use these tools; but then, when the difficulty of so doing is once -mastered, nothing can be more rapid or more satisfactory than the work -which they will do. Small bowls are hollowed almost instantaneously by -their means in skilled hands; whereas, with other tools, it becomes not -only a tedious job, but if it is done at all, it is but roughly, the wood -having to be rather scraped out than cut. Using, however, the back of the -gouge as explained before, in the directions given for squaring up the -end of a cylinder with this tool, it is possible to hollow out soft wood -with it, but not very satisfactorily. In any case, other tools (generally -a carpenter’s chisel) must be used to work into the angle which neither -the gouge nor hook-tool can, of course, reach. Hence it is generally so -much easier to cut out boxes and such like articles in box or _hard_ -wood, that this is nearly always used by amateurs. - -The ordinary way to turn a box is as follows:—Prepare the wood as usual, -turning it cylindrical, using any chuck you please for this work; cut off -with the parting-tool rather more than the box and its cover together -will require, and drive the piece thus separated into a cup-chuck. [You -may, if you prefer it, screw upon the nose of the mandrel, or upon the -taper screw-chuck, the rough piece of the proper length, instead of first -turning a cylinder to cut from. If you have several boxes to make of one -size, the cylinder method is to be preferred.] Turn it up again quite -true, for although it was correct before you cut it off, it will not be -so now. Square up the end, and turning round the rest so as to stand -across the face of the wood, begin to hollow out _the cover_. Use either -the round end or pointed tool at first, and then a carpenter’s chisel or -flat tool to finish. Be very careful that the sides (I must call it by -this name, although a circle has not more sides than a plum-pudding) are -turned square to the bottom, or else, when the cover is put on, it will -perhaps fit just at the entry, and be quite loose when fairly on; or, it -may be that it will be easy at first, and when you press it on, it will -be tighter and become split,—a very common but unpleasant occurrence. Do -not, moreover, turn down these sides as thin as they will ultimately be; -because, after the box is hollowed and the cover fitted on, both will -have to be slightly turned together to finish them nicely. Moreover, you -may not wish your box to have plain sides, but may prefer to mould them -into a more elegant form. All these little questions have to be duly -considered in turning, for a mistake is often made, and the work spoiled, -for want of a little timely consideration. - -The next point on which you have to be on your guard is this,—having -turned out the cover, you have to cut it off, not with a saw, but with -your parting-tool. Now, be sure to leave thickness enough for the top -of the cover; or, just as you think you have nearly severed the latter -from the rest of the piece of wood, you will see a beautiful little ring -tumble off,—sad relict of your box cover, which has come to an untimely -end. - -The sliding square of the turner, of which I gave a description among -the list of tools, will always enable you to gauge both the depth to -which the work is hollowed out, and also the squareness of the inside -to the bottom. But if you have no turner’s square, you can easily gauge -the depth inside, and thus see how much is necessary to be allowed for -the thickness of the top. Keep the parting-tool edgewise on the rest, -which should be raised to such a height that, when this tool is laid -horizontally across it, it will point nearly to the centre of the work, -_i.e._, the axis of it. After the parting-tool has cut into the wood a -little way, widen the groove a little, and continue to give the tool a -little play right and left, unless its end is so much wider than its -blade generally that it will clear itself perfectly as it goes deeper and -deeper into cut. If it should bind, it is almost certain to break, for -it is a very thin tool; and it is better to waste a little more of your -material than to have to replace a spoiled tool. - -I shall suppose that you have now succeeded in cutting off the cover; -pick it up and lay it near you. Directions are given generally to turn -down next the flange upon which the cover of the box is to be fitted, but -this is not to be wholly done yet, and you may proceed to hollow it out -as soon as you have turned down just so much of this flange as will show -you how much to leave in hollowing out the box. If you _fit_ the cover -before you have hollowed out the box, you will have the mortification of -finding it a great deal too loose when the box is finished, because the -latter will contract in size as soon as ever the solid core is removed -from it. _After_ you have hollowed it out, you must gauge the inside of -the cover, and the outside of the place that it is to occupy, with the -in-and-out callipers, or with a common pair, and turn the flange till -it is almost correct to this gauge, and only a very little larger than -it ought to be. When this is the case, do not trust any longer to the -callipers, but try on the cover again and again until you get a nice fit. -You must finish the flange with a chisel, held flat; and again I repeat -the caution about keeping it truly square, so that the cover will hold -equally tight in all positions. When this is the case, leave it on, and -give a last touch to both box and cover together, when you ought barely -to be able to see the joint. - -You have now only to cut off the box as you did the cover, using the same -precautions. Before it is quite severed, however, you should give it a -polish. Pick up a handful of shavings, and while the work is revolving as -rapidly as possible, hold them with some pressure against it. Every fibre -will be at once laid smooth, and it will look nice and bright at once. -You can varnish it afterwards if you like, or French-polish it. Varnish -is best for boxwood, and French-polishing requires special directions, -which I shall give you separately in a future page. - -To be able to make a box _well_, with its cover well fitted, is to -be able to do all kinds of similar work. Yet in these may be special -_details_ deserving notice. Probably, therefore, when speaking in a -future page of particular objects which have to be turned, such special -details will be more fitting than if given here. I shall therefore pass -on to another part of the subject, namely, screwed and twisted work. - - -SCREWS AND TWISTS. - -Neither of these can be very accurately made without special and somewhat -expensive apparatus; but both can with practice be done tolerably well -by the young mechanic with ordinary simple means. I need not describe -a screw, for all boys know what it is; and sporting boys, of which -in these days there are many, know what sort of _animal_ a screw is. -Well, never mind. I am always riding a screw, I believe, for it is my -hobby, and there is a great deal of science in a screw; and as for the -_variety_ of the manufactured article, there is plenty of it. There is -the corkscrew, which is, after all, not a screw, but a twist,—and this is -often the means of making men screwed; and the miserly screw, who skins -fleas for the sake of their fat; and there is the mythical, invisible, -moral (and im-moral) screw, which hard-fisted men inflict upon their -weaker brethren; and there is the gigantic screw of the _Great Eastern_ -steamship; and the minute, microscopic screw of the lady’s tiny jewelled -watch. - -There are several modes of cutting screws, in the lathe and out of -it. The small ones required for holding together the different parts -of machinery, as well as larger ones for the same purpose, are always -cut with stock and dies. The very small ones used by watchmakers, and -all below one-eighth of an inch diameter, are made by the screw-plate. -But when either large or small screws are required of great accuracy, -they are invariably cut in the lathe, and with the aid of mechanical -appliances of the most delicately accurate description. These are all -metal screws. But the young mechanic will often wish to put screwed -covers to his boxes, and to join various parts of his work by screwed -connections instead of glue; and all these may be cut in the lathe -by simple hand-tools skilfully applied, although the operation is -sufficiently fraught with difficulty to require a great deal of practice -before it can be done with certainty of success. At the same time, my -young friends cannot possibly do better than practise this operation, for -there are numberless cases in which screws cannot be conveniently cut in -any other way, and it is, further, an accomplishment that will at once -stamp them as skilful workmen. - -[Illustration: Fig. 51.] - -The tools required are represented at A, B, Fig. 51. A is an outside, -and B an inside screw chasing-tool. These are always made in pairs, of -exactly the same pitch, _i.e._, the outside tool being applied to the -inside, the respective notches and points will exactly fit into each -other. If you were to examine the under side of these tools, shown at C, -you would notice that the notches do not run straight, but slanting. They -are in fact parts of screw threads; and you could make a tool of this -kind out of a common screw nut, as I have shown you at D, only it would -be too much hollowed out to make a good tool. - -Now, supposing you were to hold the tool A flat on the rest, while a -cylindrical piece of wood revolved in contact with it, you would cut -a series of rings only; but if you were at the same time to slide the -tool sideways upon the rest, so that by the time the wood had revolved -once, the first point of the tool would have just reached the spot which -was occupied by the second when you started, you would have traced a -screw thread of that particular pitch. This is what you have to learn -to do always, and with certainty, no matter what pitch of tool you may -be using, and it is easy to understand how difficult the operation must -be to a beginner. Indeed, there are numbers of otherwise good turners -who have never succeeded in mastering this work. Nevertheless it can -be done, and, although difficult, it is not so much so as might be -supposed. Indeed, at first sight it would hardly be believed _possible_, -because each different pitch of tool, and each different-sized piece of -work, requires a different speed of traverse to be given to the tool. -But a practised hand will strike thread after thread without failure, -and those whose trade is to make all sorts of screw-covered boxes and -similar articles, will execute the work with as much speed and apparent -ease, as they would any ordinary operation of turning. I shall tell -you by and by, however, of several ways to escape this difficulty -of screw-cutting,—lathes being fitted in various ways to insure good -work, in some cases by carrying forward the tool at exactly the right -rate of traverse, and at others by moving along the work itself at the -proper speed, while the cutting tool is held immovably fixed in one -position,—and I will give one tool of great service which will guide you -in starting the ordinary chasing-tool; and a good start is here truly -“half the battle.” - -The chasing-tool must run from right to left for an ordinary right-handed -screw (and a left-handed one is very seldom required), so that the young -mechanic need not trouble himself about it. Precise directions cannot be -given further than to have a rest with a very smooth and even edge, which -will not in the least hinder the traverse of the chasing-tool, and to -get the lathe into steady, equable motion. Then hold the tool lightly, -but firmly, keeping it at right angles with the work. Allow it only -just to touch until you find you have got into the right _swing_. It is -all a matter of knack and practice; and if you succeed quickly, you may -congratulate yourself. - -The inside chasing-tool is used in precisely the same way, running it -from the outer edge of the hole inwards. To some this is an easier -tool to use than the outside chaser. I cannot say that I find it so; -especially as one has to work more in the dark; unless the work is -of large diameter like the cover of a box, and even then the work -is sufficiently difficult owing to the shallowness of the lid, which -necessitates the instant stopping of the tool for a fresh cut. For -you must understand that you have to deepen the screw-threads very -gradually, and it will take several traverses of the tool to cut them to -a sufficient depth. - -The chasers require to be very sharp to cut wooden screws neatly, but -observe you must only rub the upper flat face upon the oilstone, or, if -a notch has been made by using the tools upon metal (they will cut brass -well with care), grind them in the same way; the great secret being to -hold the tool quite flat on the stone. You will thus, even by continual -grinding, only thin the blade of the chaser, which will thus last for a -long time. A practised hand will even cut a good thread with any flat -piece of steel filed into equal notches, but a screw-chaser is the only -tool really fit for the purpose. - -[Illustration: Fig. 52.] - -The most effectual remedy for the screw-cutting difficulty, is -unfortunately rather expensive in its best form. But in another, it is by -no means costly; and although it may not look so well as the first, it -is equally effective, and extensively used by the turners at Tunbridge -Wells, who make those beautiful little inlaid boxes and other articles. I -shall explain this to you, therefore, first:— - -A, is a lathe-head, something like the one I have already described, -but you will notice that the mandrel is a much longer one, and has -several short screws cut upon it, each one being of a different “thread” -or “pitch.”[1] This mandrel runs through two collars, so that, besides -turning round, it can be pushed endwise. Now, supposing I was to hold -the point of a tool firmly against either of the screws, and at the same -time was to turn the pulley and mandrel, you will understand that it -would run backwards or forwards in its collars, at such a rate as the -screw-thread compelled it to move. This is the plan of the traversing -mandrel; and now supposing that you had a box held as usual in a chuck, -and while the mandrel was compelled to move endwise as described, you -were to hold a pointed tool against it, the tool would evidently cut a -screw-thread of exactly the same pitch as that upon the mandrel against -which the pointed tool first spoken of was applied. But in practice, a -single-pointed tool held against the mandrel would not answer very well, -and so the following plan is adopted instead, which answers perfectly. - -Fig. 52, C, is called a half-nut. It has a set of screw-threads, cut -where the semicircular hollow is, which threads fit one of the screws on -the mandrel. A whole row of these half-nuts are fitted to turn at one -end upon a long bar, so that either one can be raised up at pleasure to -touch the screw upon the mandrel, which has threads of the same pitch -as itself, B. These, then, are ranged under the mandrel, and when it -is desired to make it traverse in its collars, one of these half-nuts -is raised and kept up by a wedge placed underneath it. When no screw -is required, a somewhat similar half-nut, but with merely a sharp edge -instead of a thread, is raised, and this edge falls into a notch or -groove turned upon the mandrel, or sometimes a back centre-screw is added -like D, and when no screw has to be cut, this is run up against the -mandrel like an ordinary lathe. - -In the more expensive traversing mandrels, although the principle is the -same, there is a little difference in the arrangement of the different -parts. The mandrel is not very much longer than usual; and it has no -screw-threads cut upon it. But a number of ferules like K, are made each -with a screw upon its edge, and one of these of the desired pitch is slid -upon the end of the mandrel at _b_, fig. P, and is there held by a nut or -otherwise, so that it cannot move out of its place. The half-nut is seen -at _a_. It consists of a piece of brass or steel of the form shown with a -hole in the middle, and a screw cut upon _each hollow_, so that it is a -circle or set of half-nuts of different pitches. This slips over a pin at -_a_, and when the screw _b_ is turned, it draws up this pin and the nut -attached, until the latter comes in contact with the ferule upon the end -of the mandrel. This is very neat but expensive. Now, by far the cheapest -and best way for the young mechanic, is to set boldly to work to conquer -the difficulty of chasing screws by hand. There are even disadvantages -in the expensive form of a traversing mandrel, which render it by no -means a desirable mode of fitting up a lathe, and after all, the length -of screw which it enables one to cut is very limited, and in addition, -it is not every day, nor probably once a month, that screw-cutting will -be necessary at all. My advice, therefore, is, do not get a traversing -mandrel until you can cut screws well with the chaser. When you can do -this, you will be able to judge of the advantage or disadvantage of one. - -By far the greater number of common screws are cut without the lathe, -by screw-plates, or stocks and dies, and the nut, or hole into which -such screws are to fit, is cut with a tap. A screw-plate is a simple -affair,—a mere flat plate of steel, in which several holes are drilled, -which are afterwards threaded by screwing into them taps, or hard cutting -steel screws of the size required; the plate is then hardened by being -heated red-hot and suddenly cooled, after which being much harder than -brass, iron, or steel which has not gone through such process, it will -in turn cut a thread upon any of these by simply screwing them into it. -But although this will answer for small and common screws, it is not at -all suitable for better ones, because the thread is _burred_ up, not -_cut_ cleanly as it would be with a proper tool. A far better plan is a -stock and dies; the latter being practically a hardened steel nut sawn in -half, and fitted so that the two halves can be pressed nearer and nearer -together as the screw thread becomes deeper. The dies are screwed up by -means of a thumbscrew opposite to the handle. - -To use it, a piece of iron is filed up or turned to the required size, -which must be exactly that of the finished screw. The dies are then -loosened and slipped on to the end of this screw-blank as it is called, -and are then slightly tightened upon it. All that is now required is to -keep turning the tool round and round upon the pin, which it will soon -cut into a screw thread. When the stock is at the bottom or top, you may -tighten the dies, and so work up or down; but never tighten them in any -other part. If iron or steel is to be cut, use oil with the tool, but -brass may be dry. If the screw is of steel, heat it red-hot and let it -cool very gradually, to make it as soft as possible. - -The hole or nut, into which the screw is to fit, is to be drilled so as -just to allow the taper tap to enter about a couple of threads; a wrench, -or, if small, a hand-vice is then applied to twist it forcibly into the -hole, when the thread will be completed. Take great care to hold the tap -upright, or else, if it is a screw with a flat head which has to fit into -it, it will not lie correctly, but one side of the head will touch while -the other is more or less raised. - -There are other modes of screw cutting, but at present I need only -mention one, which is used for wooden screws alone. It is called a -screw-box, and is only made to cut one size, a tap being always sold to -match. You can, however, purchase any size you like, from a quarter of an -inch to 2 or 3 inches; but the latter are only intended for very large -screws, such as are used for carpenters’ benches and various kinds of -presses. A screw-box looks like a small block of wood with a hole in it, -but if you take out two screws you will find a blade of a peculiar shape, -which forms the thread by cutting the wood as it is screwed into the hole -in the box. - - - - -CHAPTER XI. - - -HARD-WOOD TURNING. - -We now discard almost entirely the gouge and chisel used for soft woods, -and fall back upon an entirely different set of tools, similar to those -used for metal, but ground to rather more acute angles. These tools are -held horizontally upon the rest, because depressing the handles causes -the bevel below the edge to rub upon the work; and in addition, the grain -of hard foreign woods is such that it cannot well be cut by placing -the tool at a more acute angle, as would theoretically be required. -Hence we can only regard these as scraping tools; but as such they will -do excellent work in skilful hands. I have said that we discard the -gouge, but there are some woods that will bear this tool, to take off -the roughest parts of the work, before the application of others. The -roughing-tool, however, may now be considered to be the point-tool, and -the round-end tool, or “round” as it is often called; a narrow one makes -a good tool for this purpose. - -Hard wood is easier on the whole to work than soft, because we have for -the purpose a large stock of tools of all shapes, suitable to the various -mouldings required. Hollows, round-beading tools, compound and simple -moulding tools of various sizes, to say nothing of those which are made -for use with ornamental apparatus, such as are required for fluting, -beading, and eccentric work, spirals, and so forth. It is indeed in hard -wood that most amateurs are accustomed to work; ebony and ivory, singly -or in combination, being more extensively used than any other. - -To turn a cylinder, or any work requiring to be held at both ends, -you will invariably find the cross-chuck the best to use,—the fork or -prong not taking hold in the hard material. Rough down to shape as -before, using the gouge if it will work, but keeping the rest as close -as possible, and only taking a light cut. Then finish roughing with -a round-tool, and proceed generally as in soft wood turning, except -inasmuch as you have to scrape instead of cutting the work into form. - -In addition to the tools already described, you will have to obtain a few -beading-tools, if you want to do very good work, for these give far more -beautiful mouldings than you can cut in any other manner. Fig. 53, A to -C, represent these. The bevel is on the under side, and it is better to -interfere with it as little as possible, by always sharpening the flat -face only. If it should be _necessary_, however, to touch the bevel, it -must be rubbed by a slip of oilstone, rounded on the edge, as used for -sharpening gouges. Conical grinders, revolving in the lathe, are also -used, especially for small beading-tools, to be fixed in the slide-rest. -In the same figure, D and E represent another useful hard-wood and -ivory tool. It is called the side-parting tool; and it is usual to have -several of these, the hooks increasing in length. The edge is only on the -extreme end of the hook. These tools are used for economy’s sake to cut -solid blocks of ivory and hard-wood from the inside of boxes, instead of -cutting the material into a heap of useless shavings. Similar tools, G, -H, curved instead of rectangular, serve to cut out a solid piece from -the inside of a bowl. In ivory work it is essential to use these tools, -because such material is very costly; $2.50 a lb., and upwards, being a -common price. - -[Illustration: Fig. 53.] - -K is given to show what are meant by beadings. If these are exactly -semicircular in section, they are far more beautiful in appearance than -if of such curves as can be roughly cut by a chisel. The bead-tools are -beautifully formed for this very purpose. To use the same side-parting -tool, you must proceed as follows, which you will understand by the fig. -L:—A common straight parting-tool or narrow chisel is first applied to -the face of the work to cut a deep circular groove or channel, as shown -by the white space at N, and in section at L. This allows the narrowest -of the hooked tools to be applied to _under-cut_ the solid core _x_. This -being withdrawn, a rather longer hook is applied, the hook being held -downwards as at O, until it reaches the spot where it is to work, when it -is gradually turned up (bevel below). Eventually, it is plain that the -solid core or centre block _x_ will fall out entire, which may be used -for other purposes. M shows how a similar but curved block can be removed -from the inside of a cup or bowl, the curved tool not requiring an entry -to be made for it, as it cuts its own way entirely from first to last. - -P and Q show a ring-tool and the method of using it. A recess is turned -in the face of a piece of wood as if it was intended to hollow out a box. -The ring-tool is then applied bevel downwards, and with the left cutting -edge a bead is cut half-through from the inside. The right edge is then -applied to the outside, and when the cuts meet the ring neatly finished, -will fall off. With this tool you can turn them very rapidly, and they -will require only a rub of sand-paper to finish them. - -R, S, T are three more tools for hard wood. The first two cut on the -outside of the curved part all round. These would be used to hollow out -humming-tops and all similar articles, and to finish the insides of -bowls, for which T is also designed. Indeed, I might go on to describe -all possible shapes of curved tools, each intended for some special work; -but you will not do better than to go to Fenn, Buck, or any tool-maker in -London, or elsewhere, and pick out at 7s., or so, per dozen, all shapes -and sizes, or if you live at a distance and write to either of the above, -they will select you the most useful; and you can trust these tradesmen -and all first-class ones to send you no tools which are not of the best -quality. - -In finishing best work in hard wood, be very careful of all sharp edges -of mouldings. Sand and glass paper round off these, and spoil the beauty -of the work. If you are _obliged_ to use such substances, touch off again -the edges with very keen tools, which ought to leave brighter and more -beautiful surfaces than any sand-paper can produce. Indeed, the secret -of _finished_ work in hard wood is to have tools whose edges and bevels -are _polished_. In ornamental eccentric and rose-engine turning, where to -use sand-paper would be to ruin the appearance of it, the little drills -and cutters pass through three stages of sharpening, being ground on the -oilstone, finished on a slab of brass, fed with oil and oilstone powder, -and polished on a slab of iron with oil alone or oil and rouge. After -this every cut that is made with them reflects the light; and as the -surface is otherwise purposely grailed or dulled by cutting a series of -fine light rings with a point tool, the pattern itself shows out clearly -and lustrously. - - -TURNING BRASS AND OTHER METALS. - -I shall now teach you how to turn iron and brass, which, though harder -than wood, are not very difficult to cut, if you go to work in a proper -manner and understand how to use your tools. What these are like I have -already told you, and also how to mount a bar in the lathe by using the -driver or point-chuck with a carrier. If the piece to be turned is _not_ -a bar, you will have to drive it into a chuck of wood, or clamp it upon a -face-plate, or in a self-centring chuck if you have one. - -I shall suppose, first of all, a mere straight bar of iron, centred at -the ends, as I have shown you. Take off the lathe-cord that you use for -wood, and fit one to go upon the largest part of the mandrel pulley, and -the smallest upon the fly-wheel. When you now put your foot upon the -treadle to work at your usual speed, you will find the mandrel turn quite -slowly; but I may at once tell you, that what you lose in speed you gain -in power. Set your rest for iron (which is not that used for wood, but -one with a broad, flat top) so that it stands a little below the central -line of the lathe mandrel and work, which will bring the edge of the tool -exactly _upon_ that line. This is always the position of the tool for -metal-turning, at any rate for iron. - -Begin by trimming the end of the bar next to the back centre. Use a -graver, held as I directed you; that is, with the bevel flat upon the -_face_ of the iron, which is in this case the _end_ of it. Only let the -point cut, and a very little of the edge beyond it, and do not expect to -take a _deep_ cut so as to bring off a thick shaving. In metal work you -will always have to proceed slowly, but nothing is more pleasant when -once you can do it well. - -You will at first have to experimentalise a little as to the exact -angle at which to hold the tool, but you will soon find out this; and -the advantage of hand-tools is, that you can always _feel_ as well as -_see_ how they are working, and can ease them here and there to suit -the material. It is rather difficult at first to hold the tool still in -metal-working, but, like all else, it becomes easy by practice; so much -so, that to hold the tool steadily in one hand is not only possible, but -is the mode always followed by watchmakers. While you are about it, you -should turn the graver over and try it in other positions; for although -the two sides of the bevel nearest to the point are the only ones to -be used, these may be applied in either direction, because they are -both sharpened to angles of 60°, and so long as you present them at the -correct angle (the smallest possible in respect of the work), it matters -not which face of the tool lies uppermost. After squaring off one end, -the approved plan is to remove the carrier, reverse the bar, and do the -same to the other end. Then begin to turn from the right hand. Place the -graver as before, with the point overlapping the end very slightly (so as -only to use the extremity of the cutting edge close to the point), and -take off a light shaving along the bar for a distance of about half an -inch, or even a quarter, keeping the edge of the graver which is on the -rest in one position, and moving the tool, not by sliding it along the -rest, but by using the point upon which it lies as a pivot. It is very -difficult to describe this exactly, but Fig. 52, O, will help to explain -it. The tool is to rest upon one spot, and the point to move in short -curves like the dotted lines, being shifted to a new position as you feel -it get _out of cut_. The left hand should grasp the blade and hold it -tightly down upon the rest, while the right moves the handle to and fro -as required. The curved dotted lines are necessarily exaggerated, but the -_principle_ of the work is this, whether you use a graver or a heel-tool. -You should turn about half an inch quite round, and then go on to the -next, by which you will always have a little _shoulder_ upon the work for -the tool to start upon, and this will be nice, clean, bright metal, and -will not blunt the tool. But if you go to work differently, so that the -edge of the tool comes continually in contact with the rough outside of -the iron caused by the heat of the fire, and which is exceedingly hard, -the point of the tool will be quickly ground down, while the iron will -not be cut into at all. - -I need tell you no more about turning a _bar_ of iron in the lathe, -because the above directions apply in all cases; but if you have to -turn the _face_ of a piece of metal that is carried in a chuck of some -kind, you should always work _from_ the middle towards the edge, and -if the graver is used, its bevelled face will lie towards you during -the process. Take care to chuck the metal very firmly, for it is most -annoying to have it suddenly leave the chuck or shift its position after -you have been at the trouble of turning part of it truly. In such case it -is very difficult to replace it exactly as it was before, and all your -work has in consequence to be gone over again. When taking the final cut, -or before, if you like, dip the end of the tool into water, or soap and -water, and see the effect. The surface turned in this way will be highly -polished at once, and the tool will cut with much greater ease, so that -a large, clean shaving will come off. When using a slide-rest, you will -find it always better to keep water just dripping upon the work and point -of the tool; but there is a drawback, nevertheless, to this plan, for, as -might be expected, it makes a mess and rusts the lathe, and sometimes the -work as well, so the water must be constantly wiped off it. - - -THE SLIDE-REST. - -I shall now pass on to describe a mechanical arrangement called a -slide-rest, of which there are two separate and distinct forms, one -for metal and one for ornamental turning in ivory and hard wood. The -ornamental work that can be done I shall pass by for the present, -because few boys are provided with the costly apparatus required, and -I am rather addressing those young mechanics whose tastes incline them -to model machinery and to practise the various operations of mechanical -engineering on a small scale. To such a slide-rest is an _almost_ -necessary addition to the lathe, for there is a great deal of work which, -I may say, cannot be done without it; for instance, boring the cylinders -of engines (except small ones of brass), turning the piston-rods and -various pieces which require to be accurately cylindrical and of -equal size, perhaps for the length of a foot or more. Hand-work has -accomplished _something_ in this way in olden days, but the inability -of workmen to advance beyond a certain standard of perfection with -hand-tools alone, became such a hindrance to the manufacture of the -steam-engine, as improved by Watt and others, that had not Maudsley, -Naysmith, and others developed the principle of the slide-rest and -planing machine, we should not yet have lived to see those gigantic -engines which tear along like demon horses with breath of fire, at the -rate of sixty miles or more in as many minutes. So likewise would various -other machines, which now appear absolutely necessary to supply our -various wants, have stood in their primitive and imperfectly developed -forms; for it is necessary, before constructing a machine, to have the -means of turning cylindrical parts truly, and producing perfectly level -plates where required. - -The object of a slide-rest is to provide means for holding a tool firmly, -and giving it a power to traverse to and fro and from side to side, so -that by the first we may be able to cause such tool to approach or recede -from the work, and by the second we may cause it to move in a perfectly -straight line along its surface from end to end. This is accomplished -in the following manner:—The drawing being a representation of one of -the first machines constructed for the purpose. A rectangular frame, -A, of iron is carried by a pair of strong uprights, B B, fixed to the -sole-plate, C, by which it is attached by a bolt to the bed of the lathe. -Lengthwise of this frame runs a screw, prevented by collars from moving -endwise, but which can be turned round by the winch-handle, D. Thus a -nut through which this screw passes, and which only has endwise motion, -will, when the latter is turned by its handle, traverse it from end to -end in either direction, according as the screw may be turned from right -to left or the contrary. This nut is attached to the under part of a -sliding-plate, E, which has a part projecting between the sides of the -frame, and also two others on its outside, by which it grasps the same -with great accuracy, and is prevented from any shake or play as the -whole with the nut is made to traverse to and fro along the frame. - -Lengthwise of this sliding-plate, that is, in a direction the opposite to -that of its own traverse, are two bars bevelled underneath, fixed exactly -parallel to each other, which are so arranged to guide the cross traverse -of another plate with chamfered edges to fit the bevels of the guide -bars. This second plate has on its upper surface two clamps which secure -the tool. It is plain, then, that by this arrangement the two required -movements are attained, the lower plate sliding along in one direction -parallel with the lathe-bed, and the other across it. In the original -rests, this upper plate with the tool was moved by hand, and in the -modern rest for ornamental turning (which this was also constructed for) -the same is done, but a hand-lever is added for the purpose. - -But although a similar arrangement is needed for metal, it is plain -that the top plate should have a more easily regulated motion, and -that we should be able to advance the tool as near the work as may be -desired, and then to retain it securely at that distance while giving the -necessary movement in the direction of the length of the object to be -turned. The method of effecting this is at once suggested by the screw -and nut of the lower part, and by merely adding to the top a similar -arrangement, the desired end is at once attained. - -[Illustration: Fig. 54.] - -The actual construction of such rest varies somewhat, but Fig. 54, H, -shows it in its most ordinary form. The lower part is, of course, to be -clamped down securely to the lathe-bed, there being a projection below -which is made to fit accurately between the bearers similar to that -beneath the poppits. This projection secures the correct position of -the rest, of which one frame or plate will travel lengthwise of the -bed, while the other will move exactly at right angles to it. But in -the _compound_ slide-rest, which is very general, there is also a third -circular motion, by which the upper part can be set at any angle with -the lower, instead of being permanently fixed at right angles to it. By -this the tool can be made to approach the work more and more as it passes -along it; and it will therefore cut deeper at one end of its traverse -than at the other. The result will be that what is thus turned will not -be a true cylinder, but a cone, _i.e._, it will be larger at one end than -the other, although otherwise smooth and even. - -We are thus provided with the most valuable addition to the lathe ever -devised by mechanics, and it is no longer a question of the strength and -skill of the workman whether we can produce a perfect piece of work, but -simply of the accuracy with which the lathe and rest are constructed, and -of the form and condition of the tools to be used. The latter are not -exactly like those ordinarily used, although the principle of the cutting -angles already laid down needs to be adhered to even with more unfailing -attention than that required for the correct formation of hand-tools. -Moreover, it is plain that—here we shall no longer feel whether the tool -is working as it ought to do—we shall be unconscious of the precise -amount of _strain_ that is being brought to bear against its edge, and if -it is by chance working in a bad position, at a wrong angle, we cannot -re-adjust it in a moment as we could a hand-tool by a slight movement of -the fingers or wrist. - -Hence you will see at once how very important it is that tools for the -slide-rest should be shaped with the _most rigid adherence_ to correct -principles; and, further, that they should be so fixed in the slide-rest -as to meet the work at the precise angle, and at the height exactly -suited to the material of which it is composed. As regards the latter -point, it may be taken as an almost invariable rule that the work should -be attacked on its axial line (that is, a line that would run from end -to end of it dividing it lengthwise into equal parts, or, as it would -commonly be named, its _middle_ line). If the tool meets it above this, -it is most likely that it will rub against it, and the point will be out -of cut. If it meets it below, there will be a tendency for the point to -catch in, and the work to roll up upon the face of the tool, which, in -fact, it very often does with careless workmen, and then there comes a -smash of some kind—lathe centres snapped off, the tool broken, the bar -bent beyond remedy, and possibly the operator’s toes made unpleasantly -tender. - -The most common slide-rest tool for outside work is that given at H². -It is made straight, as shown, or bent sideways to right or left to -cut shoulders on the work, or enter hollows, or creep sneakingly round -corners, or any other of those crooked ways in which man delights; but -whether straight or not, these tools have all most commonly the cranked -form shown here. This gives the tools a _slight_ degree of elasticity—not -very much, because that would only injure the perfection of the work; -therefore they are not very considerably cranked. The angles are ground -as directed in the table of tool-angles, and if the point is too low, -slips of iron are placed below the shank upon the tool-plate of the -slide-rest; if too high, the grindstone must be resorted to; and the -advantage of these cranked tools is, that they can be ground down several -times without being brought too low to be packed up with iron slips to -the right level. Thus a cranked tool is by far more advantageous for the -slide-rest than one made straight like those used for hand-turning. For -inside work, however, or “holing,” the crank form is not possible, unless -the hole is of large size, and so, for this purpose, straight side-tools -are used, like K. - -If the tool is well placed, as well as correctly made, nothing can be -more easy and delightful than slide-rest work. You merely advance the -tool to take the required cut (beginning generally at the right-hand end -of the bar), and then gently turning the other handle, you will see it -traverse along, as if work was a pleasure to it, as it ought to be to all -young mechanics. Not infrequently, however, instead of this even, steady -work, the tool jumps and catches, or rubs and shrieks: it is out of -temper, I suppose; at any rate, in some one or more particulars it needs -correction. - -Although with the slide-rest you can generally venture upon taking a -deeper cut than you could with hand-tools, it is by no means well to -hurry the work. At first, especially before it has become cylindrical, -the tool will only cut partly round its surface, and the work is done in -an uncomfortable, jerking, dissatisfied sort of way, and the deeper you -drive the tool the worse it is; but as soon as the outer skin is off, and -the work has become cylindrical, a long, clear, bright shaving curls off -pleasantly from end to end, and the surface ought, if the tool is wetted, -to become at once of a finished appearance. - -You should always, with a slide-rest, take the whole run of the piece -from end to end to a certain depth, and then, commencing again at the -end, repeat the same process, and so on until the required size is almost -attained. When it is, take out the tool with the pointed end which has -been in use, and insert one freshly sharpened with a broad point, getting -it so placed as to cut the shaving both from the surface below, and from -the shoulder to which it is attached at the side, as I explained to you -in the chapter on grinding and setting tools, and which must be well -understood before you can hope to make good work with tools rigidly fixed -in a slide-rest. With this tool, kept wet with soap and water (or soda -water, which is better for this than for your stomach), take a _very_ -light shaving from end to end, taking especial care to turn the handle -which gives the traverse slowly and _evenly_. If you stop, or almost -stop, the tool will be sure to draw a little deeper into cut, which will -make a scratch upon the work, or, it may be, plough a groove, and so far -spoil the appearance of it. - -Whenever you finish turning any bar that has been centred at each end, -be careful to leave the centre marks just as they were when the work was -in the lathe. The ends will have been otherwise trimmed off at the very -commencement, and it may happen that at some future day it may be desired -to re-mount the piece for repair, when, if these marks are gone, and new -centres have to be drilled, the whole will run so much out of truth that -it will have to be entirely re-turned from the commencement. Do not, -therefore, fancy that these centre marks are unsightly, and forthwith -file them out, but be content to leave them. - -Slide-rest tools, made in the ordinary way, are so far troublesome in use -that if they get broken you must have them re-forged, and few country -smiths know anything about such matters. I have a tool now lying by me -made by a smith (true, it was a Welsh smith), and although I stood by -and explained how it should be done, and cut one out of a piece of wood, -it never arrived at a proper shape, and was never even placed upon the -rest. I keep it as old Izaak Walton kept the Londoner’s artificial fly, -viz., “to laugh at,” and as a caution to all concerned, never to go to a -country blacksmith for slide-rest tools. The following plan answers very -well for many kinds of outside work, and is on the whole a plan that may -be satisfactorily followed by the young mechanic. - -Instead of having the tools constructed from a large bar of steel half -an inch or so in the square, they are made of short pieces about an inch -long, fitted into a peculiar holder. - -The advantage of this arrangement consists in the ease with which you can -make your own tools out of broken round, triangular, or square pillar -files, small chisels and such like. These can be shaped by the grindstone -alone, and the blacksmith will not have to be called into requisition. I -shall give you two forms of tool-holders, more or less simple, because I -may suppose my young mechanic to be fast growing into an old hand, and -able to appreciate differences in these arrangements. - -Fig. 55, A, B, represents two of such holders, one for round, the other -for flat steel cutters. You can see at once that when these are upon -the bed of the rest, they form a tool with cranked end, as previously -described, and can therefore be used in precisely the same manner. I -shall give no directions for _making_ these tool-holders, which are, -nevertheless, very simple affairs, and can be readily understood from the -drawings here given. - -[Illustration: Fig. 55.] - -Another form is shown at C. The part _d e_ is a clamp, which is -separately drawn at _f_. This, like the last, enables one to use all -sorts of odds and ends for tools. There are several other patterns -of tool-holders, arranged either to use the little pieces of square, -round, or triangular steel bars, so that one side, at least, of these -may remain without grinding, and others in which two entirely new faces -must be given to the tool by the grindstone. The latter are, perhaps, -generally the best, because you can then, with the aid of the table of -tool-angles, shape your cutters very accurately to the work required of -them. - -Although such tool-holders and cutters are generally used for metals, -there are others intended for wood; and constructed to hold miniature -gouges and chisels, which perform their work admirably. A capital tool -for outside work, Fig. 55, E, which was used extensively at Portsmouth -dockyard for brass turning, is made simply by filing off at an angle of -about 45° a round short bar of steel. This angle, however, is unusually -small for brass and gun-metal, 80° being better. For iron it will answer -better, because though filed, or rather ground at 45°, the cutting edge, -a little way from what may be called the point of the tool, is nearer 60°. - -Similar to these last are the tube gouges, short bits of steel tube -ground off and sharpened. These fixed in a holder answer beautifully for -soft wood, and do not “catch in.” If the holder is bent so as to bring -the tool into proper position, inside work can be rapidly effected by -these, such as hollowing out large bowls and similar heavy work. All this -can, of course, be done rapidly with the slide-rest, so far as regards -the removal of the greater part of the wood. But in the case of a bowl, -in which a curve predominates over a straight line, hand-tools must be -used to finish it (generally the inside hook-tool). This last is, in -fact, almost identical with the tube gouge; for the slide-rest, and that -which makes it so difficult a tool to use, is that, being a hand-tool, -and subject to slight unintentional changes of position upon the part of -the workman, it catches in, and is either wrenched out of the hand, or a -piece is chopped off the wood. Rigidly held in the slide-rest, the exact -angle, once found, is of course maintained. - - - - -CHAPTER XII. - - -I now propose to assist the young mechanic in special work, instead of -continuing general directions. This will enable me to explain to him -various lathe appliances, and other details of mechanical work hitherto -passed by. - -Of all models which boys (and very big boys too) are desirous to -construct, the steam-engine holds the chief place, and deservedly so; for -every boy calling himself mechanical, ought to know how this is made, -and the general _principles_ of its construction as well. However, I am -aware, from experience, that many a youngster, who is even in possession -of a model engine, is utterly ignorant of the cause of its motion; -although it is a great delight to them to see the steam puffing out, and -the wheel revolving “nineteen to the dozen,” as schoolboys say. Now, an -engine is a very simple affair, and can be easily explained; and, as I -wish my readers to work rationally, I shall show them what they have to -do before I tell them how to do it. - -[Illustration: Fig. 56.] - -A, Fig. 56, represents a cubical vessel of tin or any other substance. -By cubical, I mean that all its sides are squares, and all exactly equal; -each side in the present case is to be 1 inch wide and long, or a square -inch. B is a similar vessel, 1 foot cube. It contains, therefore, 1728 -cubic inches, or is 1728 times as large in capacity as the first. Now, if -I were to fill the little vessel with water and tip it into the second, -and put a lamp under it, the water would all soon boil away, as it is -called. It would be converted into steam; and the quantity of steam it -would produce would exactly fill the larger vessel, without exciting any -particular pressure upon its sides. - -Steam, thus allowed plenty of elbow room, is like a lazy boy; it will -play and curl about very prettily, but will do no work. We must put some -sort of pressure, therefore, upon it—confine it, and we shall soon see -that, by struggling to escape, it will serve our purpose, and become -a most obedient workman. We have, therefore, only to put double the -quantity of water into our larger vessel, that is, _two_ cubic inches. -We will put on a cover tightly, adding a pipe through which to pour in -the water. Soon we shall have the steam formed as before; but it has no -longer room enough, and out it comes fizzing and roaring, very savage at -having been shut up in so small a cage. And we can make it work too, for -if we set up a little fan-wheel of tin right in its way, we shall see -it spin round merrily enough; or if we cork the tube lightly, we shall -find this cork soon come out with a bang. We have, in fact, already -constructed a steam-engine and a steam-gun on a small scale. The pressure -in this case is, indeed, not great, but what it is I must now try to -explain. - -The air or atmosphere, which surrounds us on all sides, exercises a -pressure upon everything of 15 lbs. on every square inch of surface. If -our little cubical inch box of tin had no air inside it, and no steam, -but was absolutely empty, each side, and top, and bottom would have 15 -lbs. pressure upon it; which would be evident if it were not very strong, -for it would sink in on all sides directly, just as much as if you -were to _add_ a weight of 15 lbs. when it was full of air, as it would -ordinarily be. - -When I spoke of the larger box being exactly filled with steam from the -evaporation of the cubic inch of water poured from the smaller box, -I supposed it empty of air. The steam from that quantity of water, -occupying the place of the air, would also be of the same pressure, 15 -lbs. per square inch of surface; and as this only balances the pressure -of the atmosphere, which would be, in such a case, pressing in on all -sides, the steam would not show any pressure; just as, if you put equal -weights into each scale of a balance, the beam of it would remain -horizontal, neither scale showing to the outward senses that it had any -pressure upon it. But in the second case, we have doubled the quantity of -steam, but compelled it to occupy the same space; therefore we have now -real, visible pressure of 15 lbs. upon each square inch; and if we again -halve the space which the steam has to occupy, or double the quantity of -water, we shall obtain a pressure of 30 lbs. beyond the pressure of the -atmosphere. - -Let us now disregard atmospheric pressure, and fit up such an apparatus -as Fig. 56, D. Here we have first our small box, closed on all sides, -and from it a small tube rising and entering into the bottom of a larger -one, which is very smooth in the inside; in this is a round plate or -disc, called a piston, which fits the tube nicely, but not so tight as to -prevent it from moving up and down easily; and let a weight of 15 lbs. be -laid upon it. Let us suppose this large tube or cylinder to be 1700 times -larger than the cubic inch box, into which water is to be poured till -full. Now we heat it as before, and when 212° of heat are attained by the -water (which is its boiling-point) when it begins to be converted into -steam, the piston will be seen to rise, and will gradually ascend, until -quite at the top of the tube, because the steam required exactly that -amount of room. - -Now we have arrived at the same conclusion which we came to before; -for you see that not only has the cubic inch of water become a cubic -foot of steam (_about_ 1700 to 1728 of its former volume), but it is -supporting 15 lbs. weight, which represents that of the atmosphere, and -if we could get rid of the latter, a solid weight of 15 lbs. would be -thus supported. Now, still neglecting the atmospheric pressure, suppose -instead of 15 lbs. we add another 15 lbs., making the weight 30 lbs., -down goes our piston again, and stands at about half the height it did -before. We have thus, as we had previously, a cubic foot of steam made to -occupy half a cubic foot of space, giving a pressure (which is the same -as supporting a weight) of 30 lbs. - -I ought, perhaps, to add in this place, however, that under 30 lbs. -pressure, or atmospheric weight and 15 lbs. additional, the water would -not become steam at a temperature of 212°, but it would have to be made -much hotter, until a thermometer placed in it would show 252°. - -So far we have seen what a cubic inch of water will do when heated to a -certain degree, and at first sight it may not seem a great deal. Far from -being light work, however, this is actually equal to the work of raising -a weight of 1 ton a foot high. Let us prove the fact. Suppose the tube or -cylinder to be square instead of round, and that its surface is exactly 1 -square inch, how can we give 1700 times the room which is occupied by the -water? It is plain that the piston must rise 1700 inches in the 1-inch -cylinder or tube, carrying with it, as before, its weight of 15 lbs.—that -is, it has raised 15 lbs. 1700 inches, or about 142 _feet_. But this is -the same as 15 times 142 feet raised 1 foot, which is 2130 lbs. raised 1 -foot, very nearly a ton, the latter being 2240 lbs. So, after all, you -see that our little cubic inch of water is a very good labourer, doing a -great deal of work if we supply him with sufficient warmth. - -Now this is exactly the principle of the ordinary steam-engine: we have -a cylinder in which a piston is very nicely fitted, and we put this -cylinder in connection with a boiler, the steam from which drives the -piston from one end of the cylinder to the other. In the first engine -that was made, the cylinder actually occupied the very position it does -in our sketch; it was made to stand upon the top of the boiler, a tap -being added in the short pipe below the cylinder, so that the steam could -be admitted or shut off at pleasure. But it is plain that although our -little engine has done some work, it has stopped at a certain point; -there is the piston at the top, and it cannot go any farther; we must get -it down again before it can repeat its labour. - -How would you do this, boys? Push it down, eh? If you did, you would find -it spring up again when you removed your hand, just as if there were -underneath it a coiled steel spring; by which, however, you would learn -practically what is meant by the _elasticity_ of steam. Besides this, -if you push it down, you become the workman, and the engine is only the -passive recipient of your own labour. Try another plan; remove the lamp, -and see the result—gradually, _very_ gradually, the piston begins to -descend. - -Take a squirt or syringe, and squirt cold water against the apparatus. -Presto! down it goes, now very quickly indeed, and is soon at the bottom -of the cylinder. But we may as well try to get useful work done by the -descent of the piston as well as by its ascent. - -Set it up like Fig. 56, E. Here is a rod or beam, _b a c_, the middle of -which is supported like that of a pair of scales. From one end we hang -a scale, and place in it 15 lbs.; and as the piston sinks the weight is -raised, and exactly the same work is done as before. Thus was the first -engine constructed; but instead of the scale-pan and weight, a pump-rod -was attached, and as the piston descended in the cylinder this rod was -raised, and the water drawn from the well. This, however, was not called -a steam-engine, because the work is not really the effect of the steam, -which is only used to produce what is called a vacuum (_i.e._, an empty -space, devoid of air) under the piston. In fact, the up-stroke of the -piston was only partly caused by steam, and the rod of the pump was -weighted, which helped to draw it up. - -I must get you to understand this clearly, so that the principle may -become plain—“clear as mud,” as Paddy would say. I told you that the -air pressed on every square inch of surface with a force of about 15 -lbs. We do not feel it, because we are equally pressed on all sides—from -within as well as from without—so that atmospheric pressure is balanced. -Sometimes this is a very good thing. We should, I think, hardly like to -carry about the huge weight pressing upon our shoulders, if something -did not counteract it for us, so that we cannot feel it. Indeed, if it -were otherwise, we should become flat as pancakes in no time—“totally -chawed up.” - -But sometimes we should prefer to get rid of the air altogether—and I -can tell you it is not easy to do so, unless we put something into its -place; and we want perhaps simply to get rid of it, and make use of the -room it occupied. We require to do this in the present instance, and in -fact we have just done it. If the whole space below the piston, when -we begin to work, is filled with water, it is plain there can be no -air below it; and when the steam has raised it, there is still no air -below it, but only steam. We then apply cold to the cylinder by removing -the lamp and squirting cold water against it, which has the effect of -reducing the steam to water again, which will occupy 1 inch of space -only. We, therefore, now have a space of 1600 cubic inches with neither -air nor water in it; and so, if the piston is 1 inch in size, there will -be the 15 lb. pressure of the atmosphere upon it, and nothing below to -balance it, for we have formed a vacuum below it, and of course this -15 lb. weight will press it rapidly down. It did so; and we therefore -were enabled to raise 15 lb. in the scale-pan. You will know, therefore, -henceforth, exactly what I mean by a vacuum and atmospheric pressure. It -is, you see, the latter which does the work when a vacuum is formed as -above; but you can easily understand that it might be possible to use -both the atmospheric pressure _and_ the pressure of steam as well, which -is done in the condensing steam-engine. - -In the earliest engine, called the _Atmospheric_ for the reason above -stated, the top of the cylinder was left entirely open, as in our sketch; -but the condensing water was not applied outside the cylinder, but -descended from a cistern above, and formed a little jet or fountain in -the bottom of the cylinder at the very moment that the piston reached its -highest point. Down it, therefore, came, drawing up the pump-rod. When -at the bottom the jet of water ceased. Steam was again formed below the -piston, which raised it as before; and the process being repeated, the -required work was done. A boy, to turn a couple of taps, to let on or off -the water or steam, was all the attendance required. - -For some time the atmospheric engine, the invention of Newcomen, was the -only one in general use; and even this was, in those days (1705-1720), -so difficult to construct that its great power was comparatively seldom -resorted to, even for pumping, for which it was nevertheless admirably -suited. The huge cylinder required to be accurately bored, while there -were no adequate means of doing such work; and although the piston was -“packed,” by being wound round with hemp, it was difficult to keep it -sufficiently tight, yet at the same time to give it adequate “play.” -Then, another drawback appeared, which, though of less importance in some -districts, absolutely prevented the introduction of this engine into many -parts of the country. The consumption of coal was enormous in proportion -to the power gained. We can easily understand the reason of this, when -we consider the means used for producing a vacuum in the cylinder below -the piston. The water introduced for the purpose, chilled, not only the -steam, but cylinder and piston also; and therefore, before a second -stroke could be made, these had to be again heated to the temperature of -boiling water. The coal required for the latter purpose was therefore -wasted, causing a dead loss to the proprietor. - -So matters continued for some time, until a mathematical instrument-maker -of Glasgow, named Watt, about the year 1760, began to turn his attention -to the subject; and having to repair a model of Newcomen’s engine -belonging to the University of Glasgow, the idea seems to have first -struck him of condensing the steam in a separate vessel, so as to avoid -cooling the cylinder after each upward stroke of the piston. This was the -grand secret which gave the first impetus to the use of steam-engines; -and from that day to this these mighty workmen, whose muscles and sinews -never become weary, have been gradually attaining perfection. Yet it -may be fairly stated that the most modern form of condensing engine in -use is but an improvement upon Watt’s in details of construction and -accuracy of workmanship. For Watt did not stand still in his work; but -after having devised a separate condenser, he further suggested the idea -of closing the top of the cylinder, which had hitherto been left open to -the influence of the atmosphere; and rejecting the latter as the means -of giving motion to the piston, he made use of the expansive power of -steam on each side of the piston alternately, while a vacuum was also -alternately produced on either side of it by the condensation of the -steam. - -The atmospheric engine was thus wholly displaced. The saving of fuel in -the working of the machine was so great, that the stipulation of the -inventor, that one-third of the money so saved should be his, raised -him from comparative poverty to affluence in a very short time. Watt, -however, had still to contend with great difficulties in the actual -construction of his engines. He was in the same “fix” as some of my young -readers, who are very desirous to make some small model, but have little -else than a pocket-knife and gimblet to do it with. For there were no -large steam-lathes, slide-rests, planing and boring machines, procurable -in those days, and even the heaviest work had to be done by hand, if -indeed those can be called hand-tools which had frequently to be _sat -upon_ to keep them up to cut. It was therefore impossible for Watt to -carry out his designs with anything like accuracy of workmanship, else -it is probable that he would have advanced the steam-engine even further -towards perfection than he did. In spite of these drawbacks, however, -this great inventor lived to see his merits universally acknowledged, and -to witness the actual working of very many of these wonderful and useful -machines. - -The first necessity which occurred from closing the cylinder at both -ends was the devising some means to allow the piston-rod to pass and -repass through one end without permitting the steam to escape. This was -effected by a stuffing-box, which is represented in Fig. 57, A, B,—the -first being a sectional drawing, which you must learn to understand, as -it is the only way to show the working details of any piece of machinery. -We have here a cylinder cover, _a_, which bolts firmly to the top of the -cylinder, there being a similar one (generally without any stuffing-box) -at the other end or bottom of the same. On the top of this you will -observe another piece, which is marked _b_, and which is indeed part of -the first and cast in one piece with it. Through the cylinder cover, _a_, -is bored a hole of the exact size of the rod attached to the piston, -which has to pass through it, but which hole, however well made, would -allow the steam to leak considerably during the working of the piston-rod. - -[Illustration: Fig. 57.] - -To obviate this, the part _b_ is bored out larger, and has a cup-shaped -cavity formed in it, as you will see by inspecting the drawings. Into -this cavity fits the gland, _c_, which also has a hole in it, to allow of -the passage of the piston-rod. This gland is made to fit into the cavity -in _b_ as accurately as possible; and it can be held by bolts as in the -fig. A, or be screwed on the surface as shown at B, in which latter case -the greater part of the interior of _b_ is screwed with a similar thread. -The piston-rod being in place, hemp is wound round it (or india-rubber -packing-rings are fitted over it), and the gland is then fitted in upon -it, and screwed down, thus squeezing the hemp or rubber tightly, and -compelling it to embrace the piston-rod so closely, that leakage of steam -is wholly prevented. Whenever you have, therefore, to prevent steam or -water escaping round a similar moving-rod in modelling pumps or engines, -you will have to effect it in this way. The piston was also packed with -hemp or tow, either loosely-plaited or simply wound round the metal in a -groove formed for the purpose. In Fig. 57, C and D, I have added drawings -of a piston, so made, partly for the purpose of again explaining the -nature of sectional drawings. In this one, C, you are shown the end of -the piston-rod passing through the piston, and fastened by a screwed nut -below, a shoulder preventing the rod from being drawn through by the -action of this nut. The hemp packing is also shown in section, but in the -drawing D the groove is left for the sake of clearness. - -In all your smaller models you will have to pack your piston in this -way, except in those where you entirely give up all idea of _power_. The -little engines, for example, sold at $1 and upwards, with oscillating -cylinders, have neither packed pistons nor stuffing-boxes; the friction -of those would stop them, and escape of steam is of no great consequence. -It will, however, be found advantageous to turn a few shallow grooves -round these unpacked pistons after they have been made to fit their -cylinders as accurately as possible, like fig. C. These fill with water -from the condensation of steam, which always occurs at first until the -engine gets hot; and thus a kind of packing is made which is fairly -effectual. - -In Fig. 58 I have given a drawing of Newcomen’s engine, in case you -would like to make a model of one; but I do not think it will repay you -as well for your labour as some others. There is the difficulty of the -cistern of cold water and the waste-well; and the condensation of the -steam is a troublesome affair in a small model, so that, on the whole, -I should not recommend you to begin your attempts at model-making with -the construction of one of these. I shall, however, add a few directions -for this work, because what I have to say about boring, screwing, and so -forth, will apply to all other models you may desire to construct. - -The cylinder, in this case, will be more easily made by obtaining a -piece of brass tubing, which can be had of any size, from 3 or 4 inches -diameter to the size of a small quill. The first you will often use for -boilers, the latter for steam or water pipes. You can also obtain at -the model makers—Bateman, for instance, of High Holborn—small taps and -screws, and cocks for the admission of water and steam, and all kinds of -little requisites which you would find great difficulty in making, and -which would cost you more in spoiling and muddling than you would spend -in buying them ready made. - -[Illustration: Fig. 58.] - -The drawing is given on purpose to show the best and easiest arrangement -for a model. It has all parts, therefore, arranged with a view to -simplicity. A is the boiler made of a piece of 3-inch brass tubing, as -far as _a_, _b_, _c_, _d_, the bottom being either of brass or copper -at the level of _a_, _b_; the upper domed part may be made by hammering -a piece of sheet brass, copper, or even tin, with a round-ended boxwood -mallet upon a hollowed boxwood block, of which T, T is a section. You -should make one of these if it is your intention to make models your -hobby, as it will enable you to do several jobs of the same kind as the -present. Probably you will not be able to make the dome semicircular, or -rather hemispherical; but at all events, make it as deeply cupped as you -can—after which, turn down the extreme edge one-sixteenth of an inch all -round to fit the cupped part exactly. This requires a good deal of care -and some skill. If you find that you cannot manage it, make your boiler -with a flat top instead. Whichever way you make it, a very good joint to -connect the parts is that shown in section at V.[2] The edge of the lower -part is turned outwards all round; that of the upper part is also turned -outwards, first of all to double the width of the other, and is then bent -over again, first with a pair of pliers and afterwards with a hammer, -a block or support being placed underneath it. All this is done by the -manufacturer with a stamping machine on purpose, and would be completed -by the Birmingham brass-workers before I could write the description. It -can, however, be done without any more tools than shown. - -You will often need a tinman’s boxwood mallet with one rounded end and -one flat one, which, of course, you can now turn for yourself, as it is -an easy bit of work. With the rounded end you can cup any round piece of -tin; but it requires gentle work; do it gradually by hammering the centre -more than the edges. I will show you presently how to do similar work by -spinning in the lathe, which is a curious but tolerably easy method of -making hollow articles of many kinds from round discs of metal without -any seam. - -After you have hammered the joint of the upper and middle parts together, -you must solder them all round with tinman’s solder. For this purpose -you require a soldering-iron represented at W. This is a rod of iron, -flattened and split at the end, holding between the forked part a piece -of copper, which is secured to the iron by rivets. I should not recommend -a heavy one, not so heavy nearly as what you may see at any blacksmith’s -or tinman’s shop, because your work will be generally light, and such -irons are all top heavy to use. The end, which may be curved over as -shown, will require to be _tinned_, for without this it will not work -at all well. File the end bright, and heat it in the fire nearly red -hot. Get a common brick, and with an old knife or anything else, make a -hollow place in it—a kind of long-cupped recess like a mussel shell, if -you know what that is, and put a little rosin into it. Take your iron -from the fire, and holding it down close to the brick, touch it with a -strip of solder, which will melt and run into the cavity. Now rub the -iron well in the solder and rosin, rub it pretty hard upon the brick, -and presently you will see it covered with bright solder, from which -wipe what remains in drops with a piece of tow. The iron is now fit for -immediate use; but remember, the first time you heat it red-hot, you -will burn off the tinning, and you must file it bright again, and repeat -the process. So when you want to solder, heat the iron in a clean fire, -until, when you hold it a foot from your nose, you find it pretty warm; -and avoid a _red_ heat. You will now find, that when the soldering-iron -is hot, it will not only melt but pick up the drop of solder; and as you -draw it slowly along a joint (previously sprinkled with powdered rosin, -or wetted with chloride of zinc, or with Baker’s soldering fluid), the -solder will gradually leave the iron, and attach itself to the work in a -thinly-spread, even coat. - -The secret of soldering is to have the iron well-heated, and wiped clean -with a bit of tow, and to apply it along the joint so slowly and steadily -that the tin or other metal will become hot enough just to melt solder. -Try to solder, for instance, a thick lump of brass; file it bright if -at all tarnished—for this must invariably be done with all metals. You -will be unable to do it at first, for the moment the solder touches it, -it will be chilled, and rest in lumps, which you can knock off directly -when cold. Now place the brass on the fire for a few seconds until hot, -and try again; the solder will flow readily as the iron passes along -it, for it is kept up to the melting-point until it has fairly adhered. -This is why in heavy work a large iron is required; it retains heat -longer, and imparts more of it to the metal to be soldered. But you -will find it often better to use a light soldering-iron, and to place -the brass-casting upon the bar of the grate for a short time. You may, -indeed, often work without any soldering-iron as follows:— - -Heat the pieces to be soldered (suppose them castings and not thin -_sheets_ of metal) until they will melt solder. Take a stick of the -latter, and just dip it in one of the soldering solutions named, and rub -it upon the work previously brightened. The solder will adhere to both -such pieces. Now, while still hot, put them together and screw in a vice, -or keep them pinched in any way for a few minutes, and you will find them -perfectly secured. In making chucks for the lathe, and in forming many -parts of your models, you will find it advantageous to work in this way; -but, notwithstanding, you will often require a light soldering-iron, and -sometimes also a blowpipe, which I shall likewise teach you to use, as -also how to make a neat little fireplace or furnace to stand on your -bench by which to heat the iron. - -I must now suppose that you have carefully soldered the dome to the -middle of your boiler; and as the solder will be underneath, the joint -will be concealed even if (as is likely) you should not have made a -very neat piece of work. Before you put on the bottom of the boiler, -you will have to make two holes in the top—one for the steam-pipe -three-eighths of an inch in diameter, the other for the safety-valve also -three-eighths—because this will require a plug of brass to be soldered -in, which plug will have a hole drilled through it of a quarter of an -inch diameter. These may be punched through from the inside, or drilled; -they are easily made, but should be as round and even as possible. - -Take a piece of three-eighths-inch tubing, with a stop-cock soldered into -the middle of it. I shall suppose you have bought this. It need not be -over an inch in length altogether; and you must put it through the hole -in the top of the boiler, and solder it round on the inside of the same. -The nearer you can get the stop-cock to the bottom of the cylinder the -better the engine will work, because the steam will have to rise through -whatever water is left in this pipe from the jet used to cool the steam. -You will see that it cannot run off by the pipe C into the pump well, -like that which collects in the cylinder itself. In a real engine the -steam-tap was a flat plate which slid to and fro sideways, level with -the bottom of the cylinder; but this you would not make easily at present. - -The plug for the safety-valve you must turn out of a little lump of -brass. It must be about three-eighths of an inch long; and you must drill -a quarter-inch hole through it, and countersink one end of the hole -(that is, make it wider and conical by turning a rosebit or larger drill -round in it a few times), to make a nice seat, as it is called, for the -valve itself, which need not be now attended to. Remember you can buy -at Bateman’s, or any model-maker’s in London, beautiful safety-valves -ready-made, as well as any part of a model engine that you cannot make -yourself; and indeed it is so far a good plan at first that it saves -you from becoming tired and disgusted with your work, owing to repeated -failures. If you buy them, therefore, you must do so before you make the -holes above alluded to, but in some respects it will be more to your -advantage to try and make all the details for yourself. I cannot call it -making an engine, if, like many, you buy all the parts and have little -left to do but screw them, or solder them, together. Don’t do this, or -you will never become a modeller. - -Your boiler from _c_ to _a_ is, in height, maybe 2 inches, the dome 1½ or -thereabout. This will slip inside the part that you see in the drawing, -and which I here sketch again separately.[3] - -[Illustration: Fig. 59.] - -A is the boiler lifted out of B, the outer case or stand, which you can -make out of tin, and paint to imitate bricks. It is almost a pity to -waste sheet-brass upon it, because it is not very important, its object -being only to carry the boiler. It is like D before being folded round -and fastened (not with solder, which would soon melt, but) by a double -fold of the joint, similar to that which you made round the boiler -itself, but turned over once more and hammered down. The holes are -punched with any round or square punch with a flat end, and are intended -to give more air to the lamp C, which should have three wicks, or two at -the least, to keep up a good supply of steam. I have shown the _flat_ -piece of tin with three legs only, which is as well as if it were made -with four; but you can please yourself in this matter. - -The lamp I need hardly tell you how to make, for it is easier than the -boiler, being merely a round tin box, in the top of which are soldered -three little bits of brass tube for the wicks, and a fourth for the oil -to be poured in—the latter being stopped with a cork. - -You should remember that no soldered work, like the inside of the boiler, -must come in contact with the heat of the lamp, unless it has water -about it, because if the water should at any time entirely boil away, -the boiler will leak and be spoiled. A little care in this respect will -insure the preservation of a model engine for a long time; but boys -_generally_ destroy them quickly by careless treatment. - -Let us now turn our attention to the cylinder. Cut off a piece of -three-quarter-inch brass tube, 2½ inches in length—you can do this with a -three-square file—mount it in the lathe by making a chuck like Fig. 59, -E, of wood, the flange of which is just able to go tightly into one end -of the tube. The other end will probably centre upon the conical point -of the back poppit, over which it will go for only a certain distance. -If your back centre will not answer on account of its small size, you -must make a similar flange to go into the other end; but take care that -when the back centre is placed against it, it runs truly. If the chuck is -well made, it will do so. You can now with any pointed tool turn off the -ends of the tube quite squarely to the side; but you should only waste -one-quarter of an inch altogether, leaving it 2¼ inches long. When this -is done, take it out of the lathe, and in place of it, mount a disc of -brass rather more than one-eighth of an inch thick, or if you have none -at hand, take an _old_ half-penny or penny piece, which is of copper, and -lay it upon the flat face of a wooden chuck, driving four nails round -its edge to hold it, and with a point-tool cut out neatly the centre, of -a size to fit inside your tube. You will scarcely, however, effect this -perfectly without further turning; so take care to cut it too large; but -before you cut it completely through, make the hole for the tube which -you soldered into the top of the boiler, which is three-eighths diameter. -This you can do beautifully in the lathe with a pointed tool, or with -a drill, centred against the point of the back poppit, as I showed you -before. - -Cut the disc quite out (too large, mind) and then turn a spindle like G, -mount the disc upon it as shown, by its central hole, and turn the edge -with a graver or flat tool, such as is used for brass, until it will -exactly fit the brass tube. You can cut out round discs of one-eighth -or one-fourth sheet-brass by mounting any _square_ piece on a wooden -face chuck, keeping it down by four nails or screws, and then with a -point-tool cutting a circle in it until the disc falls out. You will -often save time by so doing. You now have a disc of brass or copper -with a hole three-eighths of an inch wide in it; and as the disc is -three-fourths of an inch in diameter (_i.e._, six-eighths), you will have -three-eighths remaining, or three-sixteenths, each way on the diameter -between the edge of the hole and that of the disc. This will just give -room for the two small holes required, one on each side of the central -one, for the pipes from the cold-water cistern and to the well below the -pump. These must both be of brass; and the first should be turned up and -end in a jet, like a blowpipe, so as to make the water rise in a spray -under the piston; the other should be as long as can be conveniently -arranged. - -The bottom of the cold-water cistern is drawn a little above the top of -the cylinder, which is 2¼ inches high. A jet would theoretically rise in -the cylinder to nearly the height of the level of water in the cistern; -but with a small pipe, and other drawbacks inseparable from a model, you -must not reckon on more than about half that height, which should be -sufficient to condense the steam. The piston had better be nicely fitted, -but not packed. You cut a disc of brass as before, drill the hole for -the piston, make a spindle, or put in the piston-rod, and centre this -as a spindle, which is the _best_ plan, and then with a flat brass tool -turn the piston accurately to fit the tube. Or, if you think it easier, -or wish to fasten the piston with a nut, as drawn, you can, if you like, -turn it on a separate spindle; and thirdly, you may tap the hole in the -piston, and screw the end of the piston-rod. The great thing to attend to -is, to turn the edge of the piston square to the sides. - -For the piston-rod, a steel knitting needle or piece of straight iron -wire will do very well; but it will have to be flattened at the upper -end, or screwed into a little piece of brass, which must be sawn across -to make a fork by which the chain can be attached which goes over the -beam. Do not solder the cistern pipes in just yet, but go on to other -parts. - -The cistern itself can be made out of any tin box. A seidlitz-powder box -will answer well, or you can make one about that size, say 4 inches -long, 2½ wide, and 2 deep. The cistern for the pump will, of course, -require to be the same size or a little larger; it may stand on legs or -be fastened to the bed-plate direct. - -This bed-plate is shown below the picture of the engine. It is merely -an oblong plate of iron one-sixteenth inch thick, or in this particular -engine may be of tin neatly fastened to a half-inch mahogany board, which -will keep all firm. The white places show the position of the boiler and -of the pump cistern, the inner rounds indicating the lamp, and pump, and -cylinder. The square is merely made to show a boiler of that shape, which -some prefer;—it is not so good as a cylindrical one. - -Whenever you have to make an engine, you should draw upon the bed-plate -the position of each part, as I have done here, because it will serve -you as a guide for measurement of the several pieces. The four small -circles at S S show the positions of the legs of the support C, which -carries the beam. In the drawing only two are given, but there would be -a similar triangular frame upon this side. This may be made very well of -stout brass wire, but in a bought engine it would be a casting of brass, -painted or filed bright. - -The beam itself should be of mahogany, 6 inches long, half an inch wide -(on the _side_), and a quarter of an inch thick. The curved pieces you -will turn as a ring 3 inches diameter with a square groove cut in the -edge for the chain. You can then saw into four, and use two of these, -morticing the strip of mahogany neatly into them. Then finish with four -brass wires, as shown, which will keep the curved ends stiff and give a -finished appearance. The pin in the centre should be also of brass, as a -few bright bars and studs of this metal upon the mahogany give a handsome -look to the engine. - -The pump will be of brass tube, made like the cylinder, but the bucket -may be of boxwood, and so may the lower valve, each being merely a disc -with a hole in it, and a leather flap to rise upwards. The bucket, -however, should have a groove turned in its edge, to receive a ring of -india-rubber, or a light packing of tow. The end of the pump-rod must -be split to make a fork like Y, to allow the valve to rise. You can get -just such a fork ready to hand out of an umbrella, if you can find an old -one; if not, and you cannot split the wire, make the rod rather stouter, -and bend it, as shown, so as to form only one side of a fork, which will -probably answer the same purpose in so light a pump. - -The valve in both of these may be made of a flap of leather—bookbinder’s -calf, or something not too thick—and it may be fastened at one edge by -any cement that will not be affected by water, or by a small pin,—cut -off the head of a pin with half an inch of its shank, and point it up -to form a small tack. If the valve-box is of boxwood, you must drill a -hole;—you may make it, if preferred, of softer wood. - -There is no support shown in the drawing for the cold-water cistern; but -you must stand it on four stout wires, or on a wooden (mahogany) frame, -which can be attached to the bed-plate. As this last is always of some -importance, I shall add it again in this place (Fig. 60), to a scale of -three-quarters of an inch to the foot, showing the position of each part. - -[Illustration: Fig. 60.] - -Always begin with a centre line and take each measure from it, and draw -another across for the same purpose, at right angles to the first. You -will quickly see the use of this. We draw two lines as described A, B, -C, D, crossing in _o_. The longest is the centre line of beam, cylinder, -and pump. The beam is to be 6 inches long to the outside of the middle -of each arc, whence the chain is to hang. We, therefore, from the centre -point, set off 3 inches each way. At the exact 3 inches will be the -centres of the cylinder and pump;—set these off, therefore, on the plan. -The end of the tank we must have near the cylinder, because we have to -bring a pipe from it into the bottom of the cylinder. Set off, therefore, -the end of the tank 2½ inches—_i.e._, 1¼ on each side of the central -line, and draw it 4 inches in length. N shows the position of the pipe -close to the end and on the line. The centre of the boiler is the same -as that of the cylinder, so we draw a circle round it with a radius of 1½ -inches, which gives us the 3-inch circle of the boiler. Then we may set -off equal distances, N, N, for the extremities of the legs of the frame -which is to support the beam, and we complete our plan. M is the waste -pipe, and K is the opening for the water to flow into the tank. We now -find, therefore, that the bed-plate must be 13 inches long and 6 inches -wide to take the engine of the proposed size, and we may, of course, -extend this a little, if thought desirable. Mark off on the bed all the -lines of the plan as here given, and always start any measurement from -one of the two foundation lines, or else, if you make one false measure, -you will carry it on, probably increasing the amount of error at every -fresh measurement. Let this be with you a rule without exception. It is -plain that if you work all parts of your engine to size, you can set it -up on the marked bed-plate with perfect accuracy. - -The description I have given will not only enable you to make a Newcomen -engine with very little difficulty, but will give you an insight -generally into this kind of work; and you will learn, too, a practical -lesson in soldering, turning, and fitting. I must, nevertheless, help you -a little in putting your work together. - -You had better begin by soldering into the bottom of the cylinder the end -of the _steam-pipe_, which you have already fixed upright in the middle -of the dome of the boiler, taking care that it stands squarely across -the pipe, or your cylinder will not be upright. Then place the boiler -in position, and you may fix it by turning out slightly the ends of the -legs, and putting a tack through, or screwing, if the bed-plate is of -iron,—or with help of Baker’s fluid you can solder; but this is hardly -safe work, and you had better have a wooden plate, covered with tin, and -tack down the legs. I have drawn you a circular lamp, and given three and -four legs to the boiler-stand; but take care that you so arrange size of -lamp and openings of the stand as to enable you to withdraw the former -for trimming and filling. Now fit in the two small pipes, previously -bent as required. To bend them, if hard soldered or brazed, fill with -melted lead, and then bend; after which melt out the lead again. If soft -soldered, you must fill with a more fusible metal. There is a composition -called “fusible metal,” very convenient for this work, and well worth -making, because you will often need to bend small pipes into various -forms. Melt zinc, 1 oz.; bismuth and lead, of each the same quantity—this -will melt in _hot_ water; 8 parts bismuth, 5 lead, and 3 tin, will melt -in _boiling_ water. You can buy these at any _operative_ chemist’s, -either mixed, ready for use, or separately. Rosin and sand are also -used for bending tin pipes, the sole object being so to fill them that -they will become like a solid strip of metal, and thus bend slowly and -equally, with rounded and not sharp angles. - -Pass the two pipes through from beneath the bottom of the cylinder, and -solder them on the upper side of it, so that when the cylinder itself is -added these two joints will not be visible. Then set up the cold-water -cistern; block it up with anything you like so as to keep it in position, -and, inserting the pipe from below, solder this also from above, _i.e._, -on the _inside_ of the cistern. Now, arrange the frame that is to support -it, either stout wire or wood, and set it up so as finally to secure -it in its place. Now, you had better set up the pump cistern, so as to -secure the other small pipe in position, and prevent it from becoming -displaced by any accidental blow. Fix this cistern therefore also, but -leave the cover off for the present, that you may be able to solder the -small pipe _inside_ it. - -You will now, at all events, have secured the position of the most -important parts, and you may drop the cylinder into place, and solder -this also round the bottom. This would be facilitated by turning a -slight rebate, Fig. 60, S, round the disc which forms the bottom of the -cylinder, so that the smaller part of it will just fit inside it; but you -will be able to manage it without. Let the cylinder project a very little -beyond the bottom, just to allow a kind of corner for the solder to run -in; it will not show when all is fixed. Do this as quickly as you can, so -as not to melt off the solder round the small pipes. Now, make the pair -of A-shaped supports for the beam. Measure the height of your cylinder -top, above the bed-plate, and allow about another inch, and you will get -the perpendicular height to the axis of the beam. Allow 3 inches more -for each side, that is, in all for _each_ side, 3 inches longer than if -it was to be perpendicular instead of spreading. Take enough brass wire, -about as thick as a small quill, to make two such legs. Bend it in the -middle, like T, Fig. 60, and flatten the bent part by hammering, so as -to allow you to drill a hole to take the pivot on which the beam is to -oscillate. If you like to flatten all of it, and then touch it up with a -file, so as to get quite straight edges, it will look much more handsome. -Make two such pieces exactly alike, and, at distances alike in each, put -cross-bars. File a little way into each, making square, flat notches, -which will just take two flattened bars of the same wire; heat them, -and solder very neatly, so that no solder appears on the outside; file -all flat and true. In this way you can make almost as neat supports as -if they were of cast brass, and you are saved all the trouble of making -patterns. By and by, nevertheless, you must do better. - -As I have directed you in this instance to put a wooden bed-plate to your -engine, you may point the ends of the wires, and, making holes sloping at -the same angle in the wooden stand, drive the wires into them. You have -an advantage here, inasmuch as you can raise or lower your stand until -the position of the beam comes exactly right, and you find the ends drop -over the centre of the cylinder and pump-barrel as it ought to do. When -this is the case, you can cut off any wire that projects below the stand -and file it level, for it will not be likely to need more secure fixing. -The pump may now be soldered into the cover of the cistern (before the -cover itself is fastened on), and a hole must be then cut to receive the -water that will flow from the spout, and then the cover can be fitted on. -There is no need to solder it, if it is made to _fit_ over-tightly; and -you may wish, perhaps, to get at the lower valve of the pump now and then. - -The only thing left to do is to arrange the safety-valve of the boiler, -which is in many cases the place through which the water is poured to -charge it. In this engine it is, however, plain that you can fill the -boiler by turning both the taps at the same time. A little will run off -by the waste-pipe, but not enough to signify, because the tube below the -cylinder is so much the larger of the two. The safety-valve is a little -bit of brass turned conical to fit the “seat,” made by counter-sinking -the hole. It is shown at K, Fig. 59, N being the seat, O P the dome of -the boiler, and close to O is the gauge-tap for ascertaining the height -of water in the boiler. L M is a lever of flattened wire, pivoted to turn -on a pin at L,—L O being an upright wire soldered to the boiler. A notch -is filed across the top of the valve, on which the lever, L M, rests. The -weight is at M. One, as large as a big pea, hung at the end of a lever 2 -inches long, the valve at half an inch from the other end, will probably -suffice for this engine. - - - - -CHAPTER XIII. - - -WATT’S ENGINE. - -I have already told you that Watt suggested the use of steam alternately -on each side of the piston; and carried it out by closing the top of -the cylinder, and allowing the rod of the piston to pass through a -stuffing-box or gland. I now have to explain to you how this alternate -admission of the steam may be effected. - -You evidently require first an opening at the top and bottom of the -cylinder, communicating with the boiler, one only being open at a time; -but in this case, where is the steam to escape that was on one side -of the piston when the opposite side was being acted upon? It must go -somewhere, but evidently must not return to the boiler. Hence, some -method has to be contrived by which, when one end of the cylinder is -open to the boiler, the other may be open to the air or to the condenser -(in which the steam is cooled under Watt’s plan). Fig. 61 will, I think, -render clear one or two of these arrangements. - -[Illustration: Fig. 61.] - -The first is the four-way cock, a very simple contrivance, easily and -frequently used in models. You must first understand how a common water -or beer tap is made. Fig. 61, A, represents one in section, turned so -as to open the passage along the pipe to which it is attached; C is the -pipe in which is the tap, a conical tube of brass set upright, and with -a hole right and left made through it, fixed into a short horizontal -tube (generally cast with it in one piece). Into this fits very exactly -the conical plug B, also with a hole through it sideways. When this is -put into place, no water or other liquid can pass, unless the hole in -the plug is in the same direction with the hollow tube forming an open -passage. If a key is put on the square part of the plug, and it is turned -half round, the passage through the pipe will be closed. A steam tap -would be made in a similar manner, if its only office were to open and -close a passage in a tube. But we now want two passages closed and two -opened, and then the alternate pair closed and opened. This is cleverly -effected by a four-way cock. - -At D is shown a section of the steam cylinder and piston, with the -stuffing-box and all complete. A pipe enters this at the top and bottom, -and another crosses it in the middle, making four passages. Shaded -black is the four-way cock, the white places showing the open channels -through the plug. When this plug stands as at D, steam can pass from -the boiler to the top of the cylinder only, above the piston, which it -drives downward; the steam below the piston escapes through the other -open-curved channel into the air, or to the condenser. Just as the piston -reaches the bottom of the cylinder, the tap is turned, and the passage -stands as seen at E. Steam now passes to the bottom below the piston, -driving it upward, and the steam above it, which has done its work, -passes outward through the other open channel of the tap. - -You must understand that when Newcomen first set up his engine, a man had -to turn the taps at the proper moment; and it is said that one Humphrey -Potter, a boy, being left in charge, and getting tired of this work, -first devised means to make the engine itself do this, by connecting -strings tied to the handles of the taps to the beam that moved up and -down above his head. Beighton and others improved on this, and very soon -it became unnecessary for the attendant to do anything but keep up a good -fire, and attend to the quantity of water in the boiler, and the pressure -of the steam. - -In the model I gave you of Newcomen’s engine, I purposely left the taps -to be moved by hand; but F of the present figure shows how, by bringing -them near together, and adding cogged wheels or pulleys, you would make -one handle answer for both; and I shall leave you to devise an easy -method of making the engine work this one handle for itself. When Watt -made his first engine, therefore, this work had been already done, and he -only had to improve upon it, and to make it work more accurately to suit -the engine designed by himself. - -If you should chance to pay a visit to the Museum at South Kensington, -you may see, I believe, Watt’s original engine, if not Newcomen’s. The -cylinders are so large and cumbrous, that the wonder is they were ever -bored by the inefficient means then in use; and the beam is a most -unwieldy mass of timber and iron, that looks as if no power of steam -could ever have made it oscillate. Yet it was in its day a successful -engine, the wonder of the age; and did good work for its inventor and -purchaser. I strongly advise my readers to try and visit Kensington, for -there are many interesting models there, besides engines and appliances -of older days. They will thus learn what rapid progress has been made -since the days of Savery, Newcomen, and Watt; not only in the improvement -of the arrangement of the parts, but in the workmanship, which last is -mainly due to the invention of the slide-rest and planing-machine. - -We must now return to the double-acting or real steam engine, and -consider a second means whereby the steam can be alternately admitted and -exhausted. - -The four-way cock, already explained, was found to wear very considerably -in practice, and hence work loose, and a new contrivance, called the -slide-valve, soon took its place. Of this there are two patterns, the -long D-valve and the short one, which latter is used for locomotives. -There is also a form called a tappet-valve, often used for large -stationary engines, but which is noisy and subject to rapid wear. I shall -describe the long D first, in the form in which it would be most easily -made for a model engine. - -The two ports by which steam passes to the cylinder are shown at _d_, -_e_, of H, Fig. 61. C is the passage to the boiler, K is that to the -condenser. These are openings in a tube smoothly bored within, and having -at the top a stuffing-box like that on the cylinder. Within this tube -works an inner one, _b_, having rings or projections at the ends fitting -perfectly, and which are packed with india-rubber, hemp (or, in modern -days, with metal), to make a close fit. In a model, two bosses of brass, -K, soldered on the tube and then turned, make the best packing. These -packed portions of the inner tube form the stoppers to the steam ports, -_e e_, alternately, at the top and bottom. The upper part of the inner -tube has a cross arm, 3, affixed, from the centre of which rises the -valve-rod by which it is moved up and down. In the position 1, the steam -can pass from _c_ round the tube to _d_, and thence to the top of the -cylinder to which _d_ is attached. The exhaust steam passes from _e_ -below the piston by _k_ to the condenser. In the second position, 2, the -steam is evidently shut off from _d_, but can pass out at _e e_ below the -cylinder, while the communication is still open to the condenser from -_d_, through the middle of the tube to K. This is a very good form of -valve, because the exhaust is always open, and the motion is smooth and -equal. - -[Illustration: Fig. 62.] - -There are many modifications of the long D-valve, but the principle of -all is the same; I shall therefore describe the short slide-valve which -is nearly always used in the models which are purchased at the shops. -This, too, is the usual form of valve in locomotives, traction-engines, -and the majority of those in use for agricultural and similar purposes. -A, Fig. 62, is the cylinder as before in section with piston. A thick -piece is cast with the cylinder, on one side of it, having steam ports -also cast in it, which are here left white. The two as before go to -the top and bottom of the cylinder, and have no communication with the -central one, which is bored straight into the boss, and generally is -turned at right angles and connected with the condenser, or with a pipe -opening into the chimney of the engine to increase the draught by means -of the jets of steam, as is the case always in locomotives, or into the -air, which is less usual. Seen from behind, these ports are like B, -being cast and cut rectangular; and the face, B, is planed quite level, -which is absolutely necessary to the proper action of the slide-valve -which has to work upon it. This valve is a box of iron, C, with a wide -flange or rim, this flange being of sufficient width to close either -port. If this valve is placed as it stands when the engine is at rest, -_b_ covers the upper steam port, and _a_ the lower; while the exhaust or -middle port is open to the hollow part of the box. Now, if we slide the -valve downwards until the upper port is open, the other two will be in -communication, being united by being both together in the inside of this -box or valve. Suppose the valve then cased in, and that steam is admitted -from the boiler into the case, it is evident that such steam could freely -pass to the top of the cylinder above the piston to force it downwards, -while that which was below would escape by the lower port into the box, -and thence pass to the condenser. If, instead of pushing down the valve, -we had drawn it upwards, the lower port would have been opened, and the -upper and middle would have been brought into communication inside the -valve, and the contrary effect would have been produced upon the piston. - -This is the arrangement adopted, and which will be clearly understood -from the following sectional drawing, D. _a_, _a_, is the thick casting -upon the cylinder, with the upper and lower steam ports, which end -towards the middle of the cylinder, with the third port lying between; -then _b_ is a section of the valve, in such a position that the flange -of it no longer covers the lower steam port, while the other two are -open together on the inside of the valve. The latter is cased in by the -valve-box, _e e_, in the back of which is the steam pipe _f_ coming from -the boiler. The valve-rod, which is moved by the engine, passes at _o_ -through a stuffing-box. It is evidently necessary that this slide-valve -should fit, and work very smoothly and correctly against the face of the -ports, so as not to allow any escape of the steam. It is not, however, -packed in any way at the back (although springs have been sometimes -added), because, as the back is subjected to the full pressure of the -steam from the boiler, this keeps it quite close to its seat. The rod, -however, by which it is worked, might prevent this close contact of the -two surfaces if it was screwed into the valve; it is therefore made with -a cross, E, at the end, which falls into a notch in a boss cast upon the -back of the valve as seen at F. This allows a certain degree of play in -one direction, and permits the steam to press it close even after it has -become worn by use. - -You will, I think, now clearly understand how steam can be admitted -alternately to the top and bottom of a cylinder, and how the exhausted -steam that has done its work escapes. I must therefore now tell you how -the rod of the slide-valve is moved up and down by the engine, but to do -this, I must draw such engine complete. - -[Illustration: Fig. 63.] - -The cylinder, A, is screwed down on its side upon the bed-plate, R R, out -of which are cut two holes, one for the fly-wheel, P, of which part only -appears for want of space, the other for the crank, L, on the end of the -axle, M M, running through bearings, N N. The slide-valve-box is at B, -C being the steam-pipe from the boiler. The piston-rod has necessarily -to move only in a straight line in the direction of its length, but -the crank which it has to work to turn the fly-wheel must needs move -round in a circle. Hence, a poker-and-tongs joint, F O F, is arranged. -The connecting-rod, H, which is attached to the crank by brasses at K, -divides or is attached to a forked piece, at the lower end of which are -a pair of bearings or brasses, F F. The piston-rod carries the piece O, -the cross-bar of which is turned, being, in fact, the pin which passes -into these bearings at F F. This forms, therefore, a hinge-joint at this -place, so that although the piston-rod cannot leave the right line, and -can only slide in the guide, E, the rod, H, has an up-and-down motion -upon this hinge, allowing the revolution of the crank-pin to take place. -D is the valve-rod, in which is a hinge at S, which suffices for the -slight movement required in the rod, as it rises and falls by the action -of the eccentric, T, the motion and effect of which I now have to explain. - -V is a round disc of metal with a recess on its edge, so that it is like -an ordinary pulley, but large in proportion to its thickness. A hole -for the main crank axle, to which it has to be firmly keyed, is made -through it, but _not in its centre_ (hence its name, eccentric—out of the -centre). As the axle revolves, it is evident that this disc revolving -with it will carry any point, Y, of its surface round in a circle; the -centre of which is on the central line or axis of the crank-shaft. I have -drawn such circle as described by the point Y, farthest from the axis; -but any and all points describe larger or lesser circles round the same -centre. The point Y may, therefore, be considered as the centre of a -crank-pin; and the eccentric might, so far as its effects are concerned, -be replaced by a crank. Now, if you turn the fly-wheel of your lathe by -hand, the crank will revolve, but the treadle will rise and fall only -in a straight line; and you will presently see how the eccentric, in -its revolution, gives just such a to-and-fro motion to the rod D, and -consequently also to the slide-valve, which it has to move. - -Round the disc V, closely encircling it, is a flat ring, shown separately -at X, with a rod, W, attached to and part of it. This ring is generally -made in separate halves, united by bolts passing through projecting lugs -or ears. The ring also fits into the groove turned on the edge of the -disc V, so that it cannot slip off sideways. This outer ring is turned -quite smooth and true on the inside, so that the eccentric disc can -revolve within it. In doing so, it is plain that the whole ring will -rise and fall, and that the rod W will move up and down, or to and fro, -like the treadle of the lathe, thereby giving motion to the valve-rod, -which is a continuation of the rod W. As the upper end, however, of this -rod has an oscillating, or up-and-down motion, this is imparted, in a -certain degree, to its other end, at the farthest distance from the -eccentric; and hence the necessity for a hinged joint at S, to prevent -the valve-rod from partaking of this movement. It is, however, very -slight, so that the rod of the valve is not often made to pass through -guides like the piston. The whole movement of the valve-rod is very -limited, its traverse only being required to be sufficient to shift -the valve the width of one of its ports at each stroke. The length of -_stroke_ or traverse which can be obtained by the eccentric is always -equal to twice the distance between its real centre, and that on which it -turns, which will always be a guide to you in making an engine. - -[Illustration: Fig. 64.] - -The drawing here described is a plan, _i.e._, a drawing viewed directly -from above; therefore I cannot show you the perspective view of the -parts, which are, indeed, in many cases only suggested by the shading. -I have, therefore, added a second drawing of the several details. This -engine is, in construction, the simplest that can be devised with -a slide-valve, there being no additions beyond what are absolutely -necessary to make it work; the exhaust-port is below, opposite to the -letter B on the valve-box. A, Fig. 64, is the forked connecting-rod, -marked H in the previous drawing. This is cast with forked ends, _x_, and -_x_ Y (the latter being F F of Fig. 63). These ends receive brasses in -the following way, the end _x_ being represented on a larger scale at B, -with such brasses in place; of these there are two shaped like D. One of -these lies in the fork of the connecting-rod end. A second similar one -lies in the strap of iron C, which reaches beyond the first. A cotter or -key, which is, in fact, a wedge of iron, is then passed through a slot -in the strap, and a similar one in the rod; and being driven home, draws -the two brasses tightly together, causing them to embrace the crank-pin, -L, Fig. 63, or any similar bearing. All shafts that revolve in bearings -are made to pass through brasses, and whenever these occur at the end -of a rod, they are fitted as here described. E is another bearing of -cast-iron, also fitted with brasses; but in a case like this, a plate -lies on the upper one, and is screwed down by bolts and nuts as required. -This bearing would do very well at E, Fig. 63, as a guide for the -piston-rod; but in models such guide is commonly made without brasses, -like F or G of the present drawing. - -At H, I have shown the part F O F of the drawing 63. The middle is -of brass or iron; if of the former, _g g_ must be separate, as these -gudgeons would not be substantial enough, unless of iron or steel. It -is essential that K L, the piston-rod, should be in one right line; -but, if this is attended to, they need not necessarily be one piece; -and frequently the piston-rod, L, is fixed into one end of the central -casting, and another rod, K, is screwed into the other. In a model, the -piston-rod should pass quite through, and _g g_ should be two separate -gudgeons screwed in, and then turned together in the lathe, to insure -their being exactly in one line. These go into the brasses in the forked -ends of the connecting-rod, to form a hinge at that part, as will be -understood by a reference to Fig. 63. - -At M, I have shown another simple eccentric and rod, which is less -trouble to make in a model than the other. In this the ring is made in -one piece, with a round rod screwing into it. The disc has a slight -groove turned in its edge, and a small screw, P, passes through the -ring and falls into this groove. This suffices to prevent the ring -from falling off sideways, and of course is not screwed down so tight -as to prevent the disc from revolving. This is a very easy way to fit -the eccentric, and is generally followed in small engines. The lattice -eccentric rod is nearly always used in large beam engines. - -I do not think the reader will now have any difficulty in understanding -the precise arrangement of the various parts in the simple horizontal -engine of which I have given a sketch. It is a neat and convenient form, -easily arranged as a model, and I shall proceed at once to the practical -work of constructing this, and engines in general, presupposing a -knowledge of the use of the lathe, and of the few tools required. - - - - -CHAPTER XIV. - - -HOW TO MAKE AN ENGINE. - -The very first mechanical work of difficulty, but of pre-eminent -importance, in making an engine, is boring the cylinder, that is, if -the same is a casting, and not a piece of tube ready made and smooth on -the inside. This is, properly speaking, lathe work, yet may be done in -a different way. Suppose you have bought your entire set of castings, -which is the best way, and that the cylinder is half an inch diameter -inside, which is a manageable size to work upon. Get a half-inch rosebit, -which is very like the countersinks sold with the carpenter’s brace and -bits. Mount it in the lathe in a chuck, A, Fig. 65. Unscrew the point of -the back poppit, and slip over the spindle a boring-flange, B, which is -merely a flat plate like a surface chuck, only the socket is not screwed -but bored out, generally large enough to slip over the spindle. Sometimes -there is, however, a screw at the back, to screw _into_ the spindle, the -same as the points or centres. On the face of this lay a piece of board -of equal thickness, but it is as well if not planed, as its object is -partly to prevent the cylinder from slipping about during the operation, -as it is sometimes inclined to do upon the smooth metal flange, and -partly to prevent the borer or rosebit from coming in contact with the -flange when it has passed through the cylinder. Grasp the latter in the -left hand, and you can easily prevent it from revolving with the drill, -which will go through rapidly, and leave the hole beautifully finished -and quite true from end to end,—indeed, I have bored iron also, rapidly -and with great ease, with this tool. - -[Illustration: Fig. 65.] - -It is absolutely necessary, remember, that this hole bored in the -cylinder should be at right angles to the _ends_ of the same, and to -secure this you must now make use of it to mount the cylinder in the -lathe to turn these ends or flanges. I will show you a simple and easy -way to do this. C is a bar of iron or steel, preferably of the latter, -about 6 inches long, and three-eighths diameter, filed into six sides. -It is a good plan to have three or four sizes of such bars, with centre -holes drilled carefully into each end, so that you can mount them with a -carrier-chuck, as you would if you were going to turn them. Taking one of -about the size named, mount upon it a piece of wood, and turn this down -until your cylinder will just go tightly upon it. Being a six-sided bar, -it is easy to mount the wood upon it by boring the latter with a gimlet -and then driving the bar into it. It will hold tightly, and not turn -round upon the metal. The cylinder being fixed in this way, you must turn -the two flanges with a graver if the cylinder is of iron, but with a flat -tool or the four-sided brass tool if of the latter metal; and also turn -the edges of the flanges. The rest of the cylinder will be left in the -rough, and may be painted green or black. I should advise you always to -bore the cylinder first when possible, and then to mount it as described -and turn it on the ends, which are thus sure to be correctly at right -angles to the bore. Some cylinders, however, especially short ones, may -be squared up first, and then mounted on a face-plate and bored. Unless, -however, you have either a grip-chuck, which is self-centring, or some -clamps properly constructed for this particular work, you will find the -first method the easiest, especially for small light work. - -You should now make the ports for steam and exhaust. Mark them upon the -flat part of the casting, after you have filed this as level as you can, -and do not mark them so long as not to leave you room beyond the _ends_ -of the ports for the steam-box or case which has to be placed here. The -upper and lower ports are to be the same size, but the middle one may be -a trifle larger with advantage. In larger engines these are cast in the -metal, and have only to be trimmed and faced; but in the small models -you have to drill them out in the boss cast on the cylinder. Drill down -from the top, as shown at D by the dotted lines, but take great care -not to go farther than the _outer_ ports, which are to be therefore -first made, so that you can tell when the drill has gone far enough. If -you pierce the middle port from either end, the cylinder is spoiled. -To cut the middle one, you merely drill a hole straight in towards the -cylinder, and meet it by another drilled from the side, into which the -pipe for the exhaust is to be screwed. You also drill straight through -into the cylinder at _a b_, and you then plug the end of _f_, and that at -the other end of the cylinder. Your port faces, however, are generally -oblong, and not round. Make a row of holes with the drill, and then, with -a little narrow steel chisel and light hammer, chip out the superfluous -metal, and finish with a small file. You can always make narrow channels -with squared sides by thus drilling two or more holes, and throwing them -into one with a file; but in reality, for these small engines, it is very -little matter whether the ports are round in section or square. - -The bottom and top of the cylinder demand our next attention. E and F -show these. They are easily and instantly mounted in a self-centring -chuck, but can be held very well in one of wood carefully bored with a -recess of the right size and depth. You must here, nevertheless, be very -particular, else you will get your work untrue at this point, and then -your piston-rod will stand awry, and all your subsequent fitting will -be badly done. I therefore give you at G a section of the chuck bored -to take the cover truly. Recess the part down to the line _a b_, to fit -the cover exactly, taking care to level very carefully the bottom of -the recess. Below this cut a deeper hole, to allow the flange in which -the stuffing-box will be to go into it. It need not, however, _fit_ the -flange. The rough casting will hold very well in a chuck like this, even -if it is of iron. You now carefully face the bottom of the cover, and -turn the slight flange exactly to fit into the cylinder; then reverse it -in the chuck, so as to get the stuffing-box outside; and in doing so, -take the greatest care that it beds flat upon the bottom of the chuck. -Turn off level the top of the flange first at _x_ of fig. E, and then -place a drill with its point against the middle of this, and its other -end (with a little hole punched in it to keep it steady) against the back -poppit centre, and carefully drill a hole down to the level of _c_, large -enough to admit the gland of the stuffing-box or nearly so; but remember -that you must not go too far, because the rest of the hole must only just -allow the piston-rod to go through it. Therefore, after you have drilled -about three-fourths of the distance, replace this drill by a smaller one, -and with it bore quite through. The advantage of beginning in this way -is, that you can now bring up the back centre of your lathe to steady -the cylinder cover while you finish turning it; and as you will have to -make a chuck only to take hold of the flange _b_, while you turn the -edge, you will need probably some extra support of this kind. I have, -nevertheless, turned an iron cylinder cover 2½ inches diameter without -any such support; the actual strain not being very severe, provided you -understand how a tool should be made and held. - -The above directions apply equally to the cylinder bottom, the great -secret in this and all similar work being to take care to bed the work -well and truly against the bottom of the recess, turned in the chuck; -this being neglected, will result in the two faces not being parallel, -which will terribly throw out of truth the rest of your work. Indeed, in -all fitting of this kind, it is absolutely necessary to be exact in the -squaring and truing of each several piece that has to be turned or filed; -otherwise no planning or clumsy arrangement will make your mechanism work -as it ought to do. Take a week, if necessary, over any part, and don’t be -content until it is _well_ done. - -Your cylinder ought now to have a finished appearance when the cover and -bottom are placed in position, but the latter have to be permanently -attached by small screws, and these I strongly advise you to buy. They -cost about 50 cents a dozen, including a tap with which to make a thread -in the holes made to receive them; or, if you prefer it, you can buy -miniature bolts and nuts at almost as cheap a rate, which would cost you -much time and trouble to make for yourself, if, indeed, you succeeded -at all. You will want four of these for the top, and the same for the -bottom, the holes for which you will make with a small archimedean or -other drill. - -The mention I have made of this reminds me that I am gradually adding -considerably to your list of tools, and it is necessary to do so if you -take up model-making. Set down, at any rate, the following:— - - ARCHIMEDEAN DRILL-STOCK and 6 DRILLS. - TABLE-VICE. - HAND-VICE or PIN-VICE. - SMALL BRASS-BACK SAWS for METAL. - PAIR of SMALL PLIERS. - -And for use in the lathe, either two or three sizes of rose-bits, or -engineer’s half-round boring bits, of which I shall have to speak -presently; and, unless you buy _all_ screws and nuts, you will want -screw-plate and taps, or small stock and dies. Files of square, round, -and oblong section are matters of course. Remember, too, that after a -file has been used on iron and steel, it is useless for brass; so use -new ones on the latter metal first, and after such use they will answer -for cast iron and then for wrought iron. You will find the cost of files -rather heavy unless you attend to this. Have neat handles to all your -smaller files, with ferules to prevent splitting. - -When you purchase the castings of the engine, you will find a valve-box -to enclose the slide and become a steam-chest, as explained. It is like -a box with neither top nor bottom, but with a flange, or turned-out -edge all round, for the screws by which it is to be attached to the -valve-facings of the cylinder. This box must have its flanges filed up -bright on their flat sides and edges—the rest may be painted. It will -exercise your skill to get the two faces flat and true, to fit upon the -cylinder; and at last you will find it expedient to put a brown paper rim -or washer between the surfaces, or a bit of very thin sheet lead, to make -a steam-tight joint. Do not solder it, if it is possible to use screws, -because this is nearly certain to get melted off; and, if not, it is not -nearly so neat and workmanlike a way of uniting the parts. You should, -indeed, in all models, put them together in such a way as to be able at -any time to separate the different pieces again, either for the purpose -of cleaning or repair; and, if you solder, you cannot easily do this. - -The valve-casing and its back are generally put on together; four screws -at the corners passing through the back and _both_ flanges into the flat -side of the cylinder. This depends, however, upon the exact shape of -these different pieces; and I can give you no special directions for a -particular case unless I could see the castings which you have to fit -together. The stuffing-box you will make quite separate, both its outer -and inner part, and screw or solder the former into place. It is seldom -cast upon the valve-casing, because of the difficulty of chucking a -cubical object safely so as to turn any part of it. - -You are not to screw or solder the valve-box to the cylinder until you -have carefully filed up the valve itself to slide upon the port face, -without the possibility of any escape of steam taking place. This needs -the greatest possible care; and probably, after doing what you can with -a flat file, you will have to put a little emery and oil between the -surfaces, and grind them to a perfect fit, by rubbing them together. This -grinding with emery is an operation frequently required in mechanical -engineering. Lathe-mandrels are fitted in this way into the collars; the -cylinder is also ground into the back poppit-head. It is not a very long -or difficult operation, but whenever you have had to use it, take care -to wipe off the emery, or it will keep on grinding. It is indeed very -difficult to do this perfectly; and for very fine work, such as fitting -the mandrel of a screw-cutting lathe (_i.e._, a _traversing_ mandrel), -oilstone powder and crocus are used, in place of emery. These, however, -cut very slowly, making the operation of grinding exceedingly tedious; -and in the present instance, emery will answer quite well enough. In -_very_ small engines, a stroke or two of a file is all that is needed to -fit the valve, which is so small as hardly to be worthy of the name; but -in an engine with cylinder of 1 or 2-inch bore, it will be impossible to -do with file alone, as well as you can with grinding. - -The piston and piston-rod should be turned at the same time, as already -suggested in treating of the atmospheric engine of Newcomen. By this, you -will avoid getting the piston “out of square” with its rod, as if you had -bored the hole for the latter askew—a not unusual occurrence. - -I do not mean to say that it is absolutely necessary for you to turn -the piston-_rod_ at all, for, in models, it is generally of round iron -or steel-wire, which is as cylindrical as you can possibly make it. -Knitting-needles are in general use for this, as being well finished and -equalised from end to end. But these are rather hard, being tempered only -to about the degree of steel-springs; therefore you must never attempt -to cut a screw on them until you have first heated the end to be screwed -red-hot, and allowed it to cool again very slowly. If you do this, a -screw-plate will put a sufficiently good thread to allow you to attach -either the piston, or the small piece of brass necessary to form the -hinge, upon the other end of the rod—that is to say, the piece marked -H in Fig. 64. Leave this for the present, however, not attempting at -present to cut either the piston-rod or valve-rod to its intended length. -You cannot do this until you have laid down the exact plan of the engine, -and marked on the bed-plate the position of all the parts. - -I shall now suppose that you have finished the cylinder, with its -slide-valve, casing, stuffing-boxes, and piston, so that you have these -in exactly the state in which you might buy them at Bateman’s and -elsewhere, if you preferred, to spare yourself the trouble of boring the -cylinder and fitting it. You can buy them just in this condition, with -the rest of the castings in the rough; but I rather hope you may prefer -to try and do for yourself the not _very_ heavy or difficult work which I -have described. - -I suppose you, indeed, to have bought the forked connecting-rod, either -arranged for brasses, or with holes drilled (or to be drilled) in the -ends, which would probably be the case for a model of the size named, and -also the various bearings, guides, and so forth required—some of which -would have to be turned, and some filed, but which ought now to present -little difficulty to our young mechanic. - -Try to keep sharp edges to all your filed work, unless _evidently_ -intending to round them; for surfaces pretending to be flat, but -partaking of a curved sectional form, characterise the workman as -undeniably a bad hand with the file, and not worth his wages. Still I -may tell you at once that nothing is so difficult as to use a file well. -It has a knack of rounding off edges, which always get more than their -proper share of its work. But this being the case, you will know what to -try and avoid. Therefore, always endeavour in filing a flat surface to -make it slightly hollow in the middle, which it is scarcely possible, -however, for you to do; but the endeavour to effect this by filing the -middle more than the edges will help you wonderfully in keeping the -latter sharp. Those, for instance, on the fork of the connecting-rod, -especially the inside ones, should be as straight and sharp as possible; -and if you round the outside edge, take care to do it so that it shall be -evident you intended it; and so with all edges, whether turned or filed. - -The disc of the eccentric can only be turned by letting it into a chuck -to something less than half its thickness, and levelling one side and -half the edge, and then reversing it; unless you prefer to drill and -mount it on a spindle upon its centre. If you do this, you will of course -eventually have two holes in it; because this first one is not that by -which it will be mounted when in place. This second hole is not, however, -of the least importance, and may be left without plugging, and, if -preferred, may become in part ornamented by drilling additional holes, -and filing them into some pattern; or if it is desired to conceal the -one it was turned upon, this can be plugged and faced off, and will then -not be the least apparent. If the outer ring, or strap, as it is called, -is to be made in two pieces, with projecting lugs, it is evident the -outside edge cannot well be turned; and, unless you have that most useful -addition to the lathe, a grip or jaw-chuck, you will have some little -difficulty in letting the ring into a wooden chuck, so as to turn the -inside. The solid ring is, therefore, preferable (if you use the first, -however, you turn it up as a single ring, and then saw it across through -the lugs), which can be let into a common chuck, with a place chiselled -out to allow the boss to project, into which the eccentric rod has to -be screwed. This boss also has to be drilled and turned on the outside. -There are several modes of chucking it which can be applied, but the -simplest is to use the carrier-chuck, and to let the ring become its own -carrier by coming against the pin, as shown in Fig. 66, A. - -When the ring is _very_ small, I should first drill the hole for the wire -rod, and then screw and mount it upon a little wire spindle, as in fig. -B, aiding this, if necessary, by the back centre. But the smallest models -require to be put into a watchmaker’s lathe or throw, and, except as -curiosities, are scarcely worth making. - -I have already told you never to undertake engine-making without first -laying down a full-sized plan on paper, with centre lines through the -principal parts, from which to take all measurements, and to mark these -upon the base-plate, as a guide to the perfect adjustment of the various -parts. Some of these are capable of a little extra adjustment after -being put in place: the eccentric rod, for instance, can be lengthened -or shortened by screwing into or out of the eccentric ring; and the -piston-rod, too, may be similarly lengthened or shortened slightly; but -try to work as near as you can to precise measure without such adjustment. - -To turn the fly-wheel, which is the last operation (including the -crank-axle), it is better carefully to drill the boss, if not already -done, marking the centre on each side, and working half through from -each, so as to insure the squareness of the hole with the side of the -wheel, which is very important. Then mount it at once upon its axle, -previously turned slightly conical, where the wheel is to be placed, and -run both together in the lathe. This will insure the wheel running true -when the engine is put together. - -In the horizontal engine which I have sketched, the crank is quite -separate from the axle; and this is the easiest way to make it. The crank -itself is filed up, like C of fig. 66, and drilled for the axle and the -pin upon which the brasses on the connecting-rod work. Turn down the end -of the crank-shaft _very_ slightly conical, until the crank will _almost_ -go over it. Then heat the crank, which will expand it and enable you to -slip it on the shaft. Dip it in cold water, and it will be as firm as if -made in one piece with the axle. This is called shrinking it on, and the -operation will often stand you in good stead, and save the trouble of -filing key-ways and making the small wedges called keys. The pin D can -in this case be turned up separately, and screwed in, which will complete -the work. - -The eccentric must evidently be placed in position before the crank is -added, and this, too, might be shrunk on, were it not that it cannot -easily be fixed in a model until the engine is set up. The best way, -therefore, is, in this case, to turn the eccentric with a little -projecting boss to take a set screw, E, Fig. 66. - -Where the axle has to pass through bearings, it must be turned down at -these parts, so that the whole will be like F. First on the right is -the journal, _e_, then the place for the fly-wheel, _d_, very slightly -conical—the smallest part being towards _e_—then the second journal, and -then another slightly conical part, the smallest end towards _a_, to take -the eccentric and crank. The fly-wheel you will key on shaft, thus:—G -represents the boss or centre of the wheel bored for the axle, and a -key-way or slot filed on one side at _a_. There is a flat place filed on -the axle, and the wheel is turned round to bring this opposite to the -key-way. A wedge or key, _b_, is then driven in, which keeps the wheel -secure, and prevents it from turning round or working loose on the axle. -If inconvenient to turn a boss and add a set-screw to the eccentric, this -also may be keyed in its place after its position has been found; but, -for the latter purpose, it should fit rather tightly on the axle, so that -it can be just moved round with the finger stiffly until its position -with respect to the crank is ascertained. - -[Illustration: Fig. 66.] - -This position I shall now endeavour to explain, using a diagram from an -American work, in which this generally supposed difficult point is thus -ably and satisfactorily explained. First, put your engine together as -if for work, and having cut the eccentric rod to about the length you -seem to require, judging from your plan drawn upon the bed-plate, turn -round the eccentric, with your fingers upon the crank-shaft, and, having -removed the cover of the valve-box, so that you can see the action on -the valve, watch the motion of the latter. Doubtless, the result will be -that one of the steam-ports will be opened clear to the exhaust-port, -while the other is nearly or entirely shut. The rod is then too long or -too short. If in a horizontal engine the port nearest to the crank is -wide open and the other shut, the rod is too long, and must be shortened -_half_ the difference only (_you_ will do this by screwing it farther -into the eccentric hoop). When the valve “runs square,” or opens and -shuts the ports correctly, set the eccentric as in the diagram, H, in -respect to the crank, _i.e._, with its widest part at right angles to -it. By running square is meant that when the eccentric is turned round -as described, the valve opens the ports equally, and does not affect one -more than the other. The line _a_ of the diagram shows that the position -of the eccentric may advantageously be a little _beyond_ the right angle -to the crank, to give what is called “lead,” _i.e._, to open the valve a -little before the piston commences its return-stroke. - -The boilers of model engines are made of tin, sheet-brass, or copper; -seldom of the latter, which is, nevertheless, by far the best material, -and one that you can braze, rivet, or solder satisfactorily, or bend into -any shape with a hammer or wooden mallet. When polished, too, its rich -red colour is very handsome. Brass is chiefly used from the facility of -obtaining tubes of it ready brazed or soldered, from which any desired -length can be cut. A brazed copper boiler will stand a great deal of -pressure; will tear, and not fly into pieces when it bursts; and may be -heated after the water has boiled away without suffering any injury. It -would certainly not be worth while to make one for a model engine with a -half-inch cylinder, but for one of 1 inch diameter and 2½ stroke; and for -larger sizes, it will amply repay the trouble; and I will show you how to -make one, with a tube or flue inside to add to the heating surface. - -I shall endeavour presently to give the proper dimensions of boilers -to work cylinders of given diameters, but the general directions here -subjoined apply to all boilers of models, whether large or small. The -main body of the boiler is generally cylindrical, and is, in fact, a -tube of sheet-metal, with riveted, brazed, or soldered seams, the last -greatly predominating in the toy engines; the result of which is, that -the first time the water gets too low, out drops the bottom, or, at the -least, divers leaky places appear, and the boiler is obliged to go to the -tinman’s for repair, its beauty being ever after a thing of the past. It -is difficult to braze in an ordinary fire; because even if, by blowing it -with a pair of bellows, you get sufficient heat, you cannot always manage -to apply your work in a good position, as you can over the hot coals of -a forge fire, where there are no bars, hobs, or other parts of the grate -standing in the way. Moreover, you often want both hands free just as the -solder commences to “run,” and forge-bellows will keep up the blast for -a few seconds after your hand is taken from the staff or handle of them. -Still, if you have no forge, which is probable, you should make a fire of -cinders or coke (the latter if possible); and if you can contrive a grate -by putting together a few bricks in some out-house, with a bar or two -of hoop-iron below for the coke to rest upon, you will have a far more -convenient fire to work at than can possibly be obtained in any ordinary -household grate or stove. You will require a pair of light tongs, which -_ought_ to be something like A, Fig. 67; but it is quite possible to -do without these if you can hold your work in any other way; as, for -instance, with a loop of iron wire twisted round it and left long enough -to form a handle. - -The first thing to do is to cut a strip of copper large enough to make -the required tube. A piece 6 inches wide will roll up into a cylinder of -about 2 inches diameter (the circumference of a circle being nearly equal -in all cases to three times its diameter, or measure through the centre). -If, therefore, you want one 6 inches across, which is the smallest size -that can be advantageously fitted with a flue or internal tube, you must -cut it out 18 inches wide, and if it is 8 in length to the bottom of the -steam dome, it will be a large and serviceable boiler, fit to work an -engine with a cylinder of 1½ bore by 2½ or 3 inch stroke, which would -drive a small lathe. But observe that if you really have pluck and skill -enough to try your hand upon an engine that will give you real _power_, -you must take care to remember that “the strength of anything is the -strength of its _weakest_ part.” So don’t make the very common mistake -of having a good boiler and ample cylinder, and then fit the engine with -piston-rod, valve-rod, and such like, too small to bear the strain which -you propose to put upon the engine. Remember that every screw and nut -and pin upon which strain is liable to fall, must be of sufficient size -and strength to bear it safely: if not, your engine will not only come -to grief in the heavy trial, but it is quite possible that you also may -become subjected to a bad scald or other disagreeable consequence of your -error. - -Whatever sized strips of copper you use for a boiler, the edges have to -come together to form what is called a butt-joint; _i.e._, they do not -overlap like the ordinary joints you see made in tin. Before you coil -up the strip into a tubular shape, you have to cut out holes for any -boiler fittings you may wish to add, such as safety-valve, steam-dome, -and gauges to ascertain the level of the water. These, however, do not -all come into the cylindrical part of our present boiler; the gauge-taps -and glass water-gauge alone having to be provided for. The man-hole, -too, which is added to all large boilers, may be dispensed with, its -object being to enable one to get at the inside, which will scarcely be -necessary if our work is well done at first. A boiler of the proposed -size should be heated with charcoal, as it would require a very large -lamp; but where gas can be obtained, it may be preferably used, a -ring gas-burner being placed below within the furnace. The object of -a steam-dome, which, in a horizontal boiler, would have to be placed -somewhere on the tube itself, is to prevent what is called priming, -_i.e._, the carrying into the cylinder water as well as steam, which -arises from the spurting caused by the violent boiling of the water. The -dome merely provides a chamber for dry steam above the general level of -the boiler, the steam-pipe passing from it direct to the cylinders. Our -present boiler will be vertical like the last, but with a flue up the -middle, and a grate fitted below. It is shown complete in Fig. 67, B, -with all the fittings usually attached. - -Having coiled up the tube by hammering it over a cylinder of wood turned -for the purpose, a little smaller than the intended size of the boiler -(the edges having been previously filed up bright, and a width of a -quarter of an inch of the upper being similarly cleaned on the inside -all along the seam), a few loops of iron wire are tied round it, at -intervals of 1 inch or 1½ inches; there being a short piece put round, -and twisted together at the ends by a pair of pliers. The object of -these is to prevent the seam from opening on the application of heat, -which it is otherwise certain to do by the expansion of the metal. -Some borax, pounded in a mortar, and heated to drive off the water of -crystallisation, is next mixed with a little water to form a creamy -paste, and smeared along the inside of the tube, upon the brightened -part, the full length of the seam. It is generally better to heat this -salt first sufficiently to dry it (or rather fuse it), because it swells -prodigiously by the first application of heat, and if the spelter is laid -on it, it often carries it off; after once fusing, it only melts quietly. - -Before applying the little lumps of spelter, turn over the tube to heat -the part opposite to the seam, so as to equalise the expansion. Then hold -it in a pair of light tongs, lay the spelter all along upon the borax, -and expose it without actually touching the coals to the heat of the -fire, urged by a strong blast. Continue this until a blue flame arises, -which shows that the spelter has melted; this blue flame being, in -fact, that caused by the burning of the zinc in the solder—spelter being -copper and zinc fused together, or, if required softer, brass, tin, and -zinc. The former is generally used, however, on copper. When the blue -flame arises, the solder runs into the joint, and the work is done. With -the hardest of these spelters, a red heat will not seriously affect the -joint, and, therefore, if at any time the water should get below the -line of this seam, so that it becomes exposed to the heat, no harm will -be done. Nevertheless, this ought never to occur, as a gauge should be -attached to every boiler to show the exact position of the water at any -given time. - -The inside tube of this boiler will be seen, from the section, to be -conical up to the level of the lower part of the chimney. This is of -copper, brazed like the cylindrical part, and is 2 inches wide below, -and 1 inch above; consequently, the strips to make it must be 6 inches -wide at one end, and taper to 3 inches at the other. If the dome -rises 2 inches from the level of the top of the cylinder, it will be -sufficient; and as this is a difficult piece of work for a boy to manage, -a coppersmith should be asked to hammer the dome into the required form, -as he will know from experience the best size of circular disc to use for -the purpose. This part is so far removed from the action of the fire that -it may safely be soldered, but it is, nevertheless, as well to rivet it, -turning _out_ both the edge of the cylinder and that of the dome. Use -copper rivets, and make the holes half an inch apart. If you find any -leakage, you can run a little solder into the joint on the inside. The -bottom of the boiler may be quite flat and brazed, a few rivets being -first put in to hold the parts accurately together. The same may be said -of the tube which passes through both this and the dome. There is nothing -equal to riveting and brazing for this kind of work. - -I may as well state however here, that as such a boiler as I have now -described is worth very good work, it would be a great pity to spoil -it; and it will be better to content yourself with smaller boilers and -engines soldered, where necessary, until you have had some practice in -brazing. This indeed is not difficult in reality, but, at the same time, -requires great care, because sometimes the solder and the work melt -at so nearly the same temperature, that, like a bad tinker, you will -sometimes make two holes instead of mending one. The brass, for instance, -used for beer-taps is very soft, and contains lead, and to a certainty -would itself melt before ordinary spelter, and could not therefore be -brazed; but the best Bristol brass, or yellow metal, will braze easily. -A blacksmith, brazing a key or other iron article, will braze it in a -different way, using brass wire, with which he will envelop the parts -thickly which are to be united, after securing their position with _iron_ -binding-wire. He then sprinkles with borax, and heats the work until the -wire runs into the joint; after which he files and cleans off level. This -makes a very good medium. - -[Illustration: Fig. 67.] - -I have spoken of _riveting_ in this place. There is no difficulty in this -work. You can buy copper rivets of all sizes, and have only to punch -holes, put a rivet in place, and hammer it so as to spread the metal to -form a second head. If the rivets are heated before being applied, they -will draw the parts closer together, because they shrink in cooling. -All large boilers are made in this way, but smaller ones of iron are -often _welded_, where such a mode of junction is possible. When you can -rivet boilers water and steam tight, you will find no difficulty in -constructing them, for you can make riveted joints where brazing would be -difficult or impossible. - -[Illustration: Fig. 68.] - -Fig. 67, B, is a half-section of such a boiler as I have just described. -Fig. 68, A, is the lower part, which is separate, and forms the furnace -in which the boiler stands, fitting it closely. This is drawn to scale, -and is half the real size. _a_ is the steam-pipe, fitted high up in the -dome, the tap, _b_, serving to turn on or off the supply of steam for -the cylinder; _c_ is the safety-valve shown in section, and care must -be always taken to make the conical part short and of a large angle, -or it may stick fast, and cause an explosion; _d_ is the glass gauge, -to show the exact height of the water in the boiler. Its construction -will be understood from the other which is attached, where the boiler -is seen in section. There is no need to have two, and this is added -solely to explain the nature of glass-gauges. The top and bottom are -of brass, being tubes screwing into the boiler, or fastened by a nut -inside; a tube, _g_, of thick glass, connects these two, so as to form -a continuous tube, one end of which opens into that part of the boiler -which is full of steam, the other opening below the water-level. Thus the -tube forms practically part of the boiler, and the level of the water is -clearly seen. The lower tap is used for blowing off water, to insure the -communication being kept open, as it might get stopped up with sediment. - -Gauge-cocks, _e_, _f_, are generally added, even where the glass -water-gauge is used. One of these should always give steam, the other -water,—the level of the latter being between the two. If the upper one -gives water, the boiler is too full; if both give steam, the boiler needs -to have water added. With these fittings, even a soldered boiler ought -never to get burnt, and will last a long time with care. - -The lower part, Fig. 67, is made like that before described, except that, -being intended for charcoal, a circular grate is used, which simply rests -upon little brackets fixed by rivets for this purpose. The flame and -heat play upon the bottom of the boiler, and also pass up the central -tube—the latter adding greatly to the quantity of steam produced. This -furnace, when lighted, may be fed with bits of coke as well as charcoal, -about the size of filberts, and will give plenty of heat. If the draught, -however, is deficient, turn the waste steam into the tube, so as to form -a jet at each stroke, and it will greatly increase it. It is in this way -that the locomotive engines are always fitted, George Stephenson having -first suggested the arrangement. Previously to this a fan had been fitted -below the grate, which was put in rapid motion by the engine, and thus a -sufficient draught was obtained. - - -THE SAFETY-VALVE. - -To find out what pressure is exerted by the safety-valve, it must be -clearly understood upon what principle it acts. I have in a previous -chapter told you that the atmospheric pressure equals 15 lbs. on each -square inch, so that if the surface of the valve which is exposed to the -air is 1 inch in area or surface, it is pressed down with a force of 15 -lbs. The steam, therefore, inside the boiler will not raise it until its -elasticity exceeds this atmospheric pressure. If, therefore, we desire -to have only just 15 lbs. per square inch pressing against the inside of -the boiler (_i.e._, a pressure of “one atmosphere,” as it is called), -we have only to load the valve so that, inclusive of its own weight, it -shall equal 15 lbs. But it is plain that we must not load it at all in -reality; for a flat plate, 1 inch square, of _no weight_, is all that -is needed, the atmosphere itself being the load. Suppose, then, that we -_do_ load it with 15 lbs. in addition to the 15 lbs. with which nature -has loaded it, we shall not find the steam escape until it presses with a -force of 30 lbs. on the square inch, or two atmospheres (which, however, -is not 30 lbs. of _useful_ pressure upon one side of the piston, if the -cylinder is open as in an atmospheric engine, but only 15 lbs.) This is -not the _strain_ which the boiler has to stand, because the atmosphere -is pressing upon it and counteracting it up to the 15 lbs., so that -this strain tending to burst it is but 15 lbs. The number of pounds, -therefore, which is straining the boiler can readily be seen; being -always that with which the safety-valve is loaded, and this is also the -useful pressure for doing any required work. Unfortunately, however, even -in the best constructed engines, a pressure of 15 lbs. upon the boiler by -no means represents that in the cylinder. Now it would be inconvenient -to place weights upon the safety-valve itself, and therefore a lever is -added, as seen in the sketch, with a weight hung at one end of it. This -is shown at B, Fig. 68, where a section of the valve is given with its -stem passing through a guide to insure the correct motion of the valve. -The lever is hinged at one end; and the rule of the pressure or weight -which is brought to bear upon the valve is, that it is multiplied by the -distance at which the weight hangs from the valve, compared with its -distance from the hinge or fulcrum. If a weight of 7 lbs. is hung at 1, -_i.e._, at a distance as far on that side of the valve as the fulcrum -is on the other side of it, 7 lbs. will be the actual power exerted; at -2, where it is twice the distance, it will be doubled, and, as shown -in the drawing, a pressure of 14 lbs. will be brought to bear upon the -valve; while, if the weight is hung at 3, it will exercise a force of 21 -lbs. This is very easy to understand and to remember. Sometimes (always -in locomotives) the weight is removed and a spring balance is attached -at the long end. Upon this is marked the actual pressure exerted; there -being a nut to screw down, and thus bring any desired strain upon the -spring. Mind, however, in case you should try this in any of your models, -that the scale marked on the balance when you buy it must be multiplied, -as before, according to the length of your lever. Thus, if I attach such -a balance at 3 of the drawing, a real weight of 5 lbs. shown by the -balance will be 3 × 5, or 15 lbs. upon the valve, and a balance _made -for such engine_ would be marked 15 lbs., to prevent the possibility of -dangerous error. - - -ENGINES WITHOUT SLIDE-VALVES EASY TO MAKE. - -Having been led on from the atmospheric engine to that of Watt’s, and -to slide-valve engines generally, I am now going backward a little to -a class easier to make, because they have no slide-valves, nor even -four-way cocks; and then I shall have done with engines. But I dare -say some of my readers will wonder why I have said so little about -condensers and condensing engines. I am sure they will wonder at it if -they understood what I explained of the advantage of a vacuum under -the piston; so that 15 lbs. pressure upon the piston means 15 lbs. of -_useful_ work, instead of 30 lbs. being required for that purpose. But -condensing engines are utterly beyond a boy’s power. They require not -only a vessel into which the steam is injected at each stroke, but there -must be a pump to raise and inject cold water to condense the steam, and -a pump to extract from the vessel again this water, after it has been -used, and a cistern, and cold and hot wells; and all this is difficult to -make _so as to act_; and I am sure no boy cares for a steam engine that -will not work. Moreover, I have given you difficult work as it is—work -that many of my readers will no doubt be afraid to try—yet I did it on -purpose; because if small boys are unequal to some of it, their big -brothers are not, or ought not to be; and mechanical boys must look at -difficulties as a trained hunter looks at a hedge—viz., with a strong -desire to go over it, or through it, or any how and some how to get to -the other side of it. Indeed, you must ride your mechanical hobby very -boldly and with great pluck, or you won’t half enjoy the ride. However, -I am quite aware that I have led you into several difficulties, and -therefore now I propose to set before you some easy work as a kind of -holiday task which will send you with fresh vigour to what is _not_ so -easy. - -The engines without slide-valves have also no eccentrics and no -connecting-rods. There is just a boiler, a cylinder, piston, piston-rod, -and crank, and you have the sum total, save and except the fly-wheel. -These are direct-action engines, the cylinders of which oscillate like a -pendulum, and the piston-rod itself is connected to the crank, doing away -with the necessity for guides. - -Fig. 69, A, shows one of these engines, and you see that the cylinder -leans to the left when the crank is turned to that side; and if you -turn the wheel to the right, the crank will presently cause it to lean -the other way; and thus, as it turns on a pin, or “trunnion,” as it is -called, it keeps on swinging from side to side as the wheel goes round. - -Now, when it is in its first position, the piston is at the bottom of the -cylinder, and it then needs to have the steam admitted below it to drive -up the piston; but when this has passed its highest position, and the -cylinder is turned a little to the _right_, the piston must be allowed to -descend, and, therefore, we must let out the steam below it. We _ought_, -at the same time, to admit steam above the piston to force it down; but, -in the simplest models, which are called single-action engines, this is -not done. The fly-wheel, having been set in motion, keeps on revolving, -and, by its impetus, sends down the piston quite powerfully enough to -overcome the slight resistance which is offered by the friction of the -parts. - -Now, you can, I daresay, easily understand that it is possible to -make this to-and-fro motion of the oscillating cylinder open first a -steam-port to allow steam to raise the piston, and then an exhaust-port -to let it blow off into the air. This is exactly what is done in -practice, and it is managed in the following manner:— - -[Illustration: Fig. 69.] - -B, of Fig. 69, shows the bottom of the cylinder, which is a solid piece -of brass filed quite flat on one side, and turned out to receive the end -of the brass tube, which, generally speaking, is screwed into it to form -the cylinder, this being the easiest way to make it. In the middle of -the upper part of the flat side you see a white steam-port, and below it -a round white spot, which is the position of the pin, or trunnion, on -which it oscillates. Fig. 69, C, is a similar piece of brass, which is -fixed to the top of the boiler. In this, on the _left_ of the upper part, -is also a port, which is connected with the boiler by a hole drilled -below it to admit steam. On the right is also a port, which is merely cut -like a notch, or it may go a little way into the boss, and then be met -by a hole drilled to meet it, so as to form the escape or exhaust port. -Between and below these is the hole for the trunnion. - -Now, you can, I think, see that if the cylinder stands upright against -this block, as it does when the crank is vertical (or upright) and on -its dead points, the port at the bottom of the cylinder would fall -between the two on this block of brass, and, as they are both flat and -fit closely, no steam from the boiler can enter the cylinder. Nor do we -want it to do so, because, if the crank is on a dead point, no amount -of steam can make the piston rise so as to move it. But now, if we move -the cylinder to the left, which we can do by turning the wheel, we shall -presently get the crank at right angles to its former position, and, -also, we shall bring the steam-ports in the cylinder and block together, -so that steam will enter below the piston. But, practically to get as -long a stroke as possible, steam is not allowed to enter fully until the -crank is further on than in a horizontal position, that is, _approaching_ -its lower dead point; and this is the position in which to put it to -start the engine. By altering the shape or the position of the port a -little, we can so arrange matters as to let steam enter at any required -moment. - -Steam having entered, the piston will rise rapidly, forcing up the -piston, and presently, by the consequent revolution of the fly-wheel, -the cylinder will be found leaning to the left, and at this moment the -piston must evidently begin to descend. At this very time the steam-ports -will have ceased to correspond, but the port in the _cylinder_ will come -opposite the exhaust-port in the brass block, and this port is made of -such size and shape that the two shall continue to be together all the -time the piston is descending; but, the moment it has reached the end -of its downward stroke, they cease to correspond in position, and the -steam-port begins again to admit a fresh supply of steam. - -The pillar attached to the brass boss has nothing to do with it, but is -one of the supports of the axle of the fly-wheel, as you will understand -by inspection of A of this same drawing. - -Such is the single-action model engine, _of no power_, but a very -interesting toy and real _steam_ engine. - -The double-action engine is very superior to the foregoing, which, I may -remark, has no stuffing-box, and of which the piston is never packed. I -may also add, that the crank is formed generally by merely bending the -wire that forms the axle of the wheel, and putting the bent end through -the hole of a little boss or knob of brass, screwed to the end of the -piston-rod. Here you have no boring of cylinders to accomplish, but the -cylinder cover, piston, and wheel (often of lead or tin) require the -lathe to make them neatly. Many an engine, however, has been made without -a lathe, and I have seen one with a bit of gun-barrel for a cylinder, -and a four-way cock of very rough construction, that was used to turn a -coffee-mill, and did its work very well too. - -But I must go at once to the double-action oscillating cylinder, in -which, although a similar mode of admitting steam is used, it is arranged -to admit it alternately above and below the piston, the exhaust also -acting in a similar manner. - -After the explanation I have given you, however, of the single-action -engine, you will, some of you, I think, jump at a conclusion almost -directly, and perhaps be able to plan for yourselves a very easy -arrangement to accomplish the desired end. All boys, however, are not -“wax to receive, and adamant to retain” an impression; for I have known -some who need an idea to be driven into their brains with a good deal of -hard hammering. Stupid?—No. Dull?—No, only slow in _getting hold_, and -none the worse for that generally, if the master will but have a little -patience; for when they _do_ get hold, they are very like bulldogs, they -won’t let go in a hurry, but store up in most retentive minds what they -learned with such deliberation. - - -THE DOUBLE-ACTION OSCILLATING ENGINE. - -The cylinder of the double-action engine is of necessity made with ports -very similar to those of the horizontal engine already described. There -is a solid piece attached to the cylinder as before, which is drilled -down to the upper and lower part respectively of a central boss, turned -very flat upon the face, and which has to work against a similar flat -surface as in the last engine. But the ports in the latter are four -instead of two, and in an engine with upright cylinder would be cut as -follows, and as shown in Fig. 70, C. - -[Illustration: Fig. 70.] - -Those on the right marked _st_ are steam-ports, which, being drilled into -one behind, are connected with the boiler. The other two marked _ex_, -are similarly exhaust-ports opening into the air. The spaces between _a -b_ and _c d_ of fig. C must be wide enough to close the steam-ports in -the cylinder, when the latter is perpendicular and the engine at rest. -When the cylinder leans to the left, oscillating on the central pin -between the ports in the middle of the circle, the lower port of it will -evidently be in connection with the steam-port in C, while the upper -port of the cylinder will be opposite to the exhaust. As the cylinder -is carried over towards the right, the upper steam-ports will come into -action in a similar way, while the lower exhaust-port is also carrying -off in turn the waste steam. The impetus, therefore, of the fly-wheel -has here only to carry the ports over the spaces _a b_, _c d_, and to -prevent the crank stopping on the two dead points. This, therefore, is -a genuine double-action engine, and will answer, even on a large scale, -very satisfactorily. If you do not quite understand the action of these -ports, cut out two pieces of card, E F. Let E represent the cylinder. -Draw circles, and cut two ports. Cut another piece of card to represent -the brass block, with ports, _c d_; pin them together through the centres -of the circles, and they will easily turn on the pin. Mark the ports, so -that you will see at a glance which are steam and which exhaust. Now cut -out the ports with a penknife, and as you work the two cards together, -swaying that which represents the cylinder to and fro upon the other, -you will see when the ports in each card agree with one another, and -which are opposite to which. This will teach you far better than any -further written explanation. You will also see that, instead of making -the steam and exhaust ports respectively with a division between, the two -steam-ports may be in one curve united, and likewise the two exhausts; -but take care not to unite the exhaust with the steam-ports. There is no -way so easy as this of reversing the action of the steam; it is, in fact, -a circular slide-valve, but wonderfully easy to make, because you have no -steam-case to make, nor any attachments whatever. - -The faces of the valve are kept in close contact in one of two -ways—either the centre-pin is fixed into the cylinder face, and after -passing through the brass boss with the ports, is screwed up with a nut -at the back; or else there is fixed a small pillar or upright on the -opposite side of the cylinder, and a little pointed screw passing through -this presses against the cylinder, and makes a point of resistance, -against which it centres, and on which it turns. This is shown at fig. -A. A small indentation is made where the point comes in contact with the -cylinder. - -In a locomotive engine there are two such cylinders, working against -opposite faces of the same brass block containing the ports. The cranks -are also two, on the shaft of the driving-wheels, and are at right -angles to each other; so that when one piston is at the middle of its -stroke, the other is nearly or quite at the end of it. Thus, between -the two there is always some force being exerted by the steam; and the -dead points of one crank agree with the greatest leverage of the other. -In locomotives, too, the cylinders generally are made as in the present -drawing, viz., to oscillate on a point at the middle of their length; -but it is just as easy to have the two ports meet at the bottom instead, -so that the point of oscillation may be low down, like the single-acting -cylinders of the last sketch, and this is generally done when the -cylinder is to stand upright. - -There is no occasion for me to draw an engine with double-acting -oscillating cylinders, because in appearance it would be like the -single-acting one; but whereas the latter is of absolutely no use, -seeing that the greater part of its motion depends on the impetus of the -fly-wheel, the former can be made to do real work, and is the form to -be used for marine and locomotive engines. For the former, oscillating -cylinders with slide-valves are used in practice; but for real -locomotives fixed cylinders are always used. Of course either will answer -in models, and it will be good practice to try both. - -I have now given sufficient explanation of how engines work, and how they -may be made, to enable my young mechanic to try his hand at such work. -The double-action oscillating engines especially are well worthy of his -attention, as he may with these fit up working models of steam-boats and -railway trains, which are far more difficult to construct with fixed -cylinders and slide-valves. I shall therefore close this part of my work -with a description of one or two useful appliances to help him in the -manipulative portion of his labour,—for here, as in most other matters, -head and hand and heart must work together. The heart desires, the head -plans, the hands execute. I think, indeed, I might without irreverence -bring forward a quotation, written a very long time ago by a very clever -and scientific man, in a very Holy Book: “Whatsoever thy hand findeth to -do, do it with all thy might.” Depend upon it, success in life depends -mainly upon carrying into practice this excellent advice. If you take -up one piece of work, and carelessly and listlessly play at doing it, -and then lay it down to begin with equal indifference something else, -you will never become either a good mechanic or a useful man. If you -read of those who have been _great_ men—lights in their generation—you -will find generally that they became such simply by their observance -of that ancient precept of the wise man. They were not so marvellously -clever—they seldom had any unusual worldly advantages; but they worked -“with all their might,” and success crowned their efforts, as it will -crown yours if you do the same. - - - - -CHAPTER XV. - - -HARDENING AND TEMPERING TOOLS. - -I promised in a previous page to describe a little stove for heating -soldering-irons, and doing other light work. It is made as follows, and -will be found very useful. - -Fig. 71, A, is a tube of sheet-iron, which forms the body of the little -stove. Four light iron rods stand out from it, which form handles, but -these are forked at the ends, and thus become rests for the handles of -soldering-irons, or any light bars that are to be heated at the ends. -Below is a tray, also of sheet-iron, upon short legs to keep it off the -table—for this is a little table-stove. C is the cast-iron grate. You can -buy this for a few pence first of all, and then you fit your sheet-metal -to it. It will rest on three or four little studs or projections riveted -to the stove inside; or you can cut three or four little places like D, -not cutting them at the bottom line, _a b_, but only on three sides, and -then bend in the little piece so as to make a shelf. If the stove is -about 4 inches high above the grate, and 2 or 3 inches below it, and 6 -inches diameter, it will be sufficiently large for many small operations; -but that the fuel may keep falling downwards as it burns, the lower part -should be larger than the upper, and, to admit plenty of air, should -be cut into legs as shown. Round the top are cut semicircular hollows, -in which the irons rest. To increase the heat, a chimney or blower, B, -is fitted, which has also openings cut out to match those of the lower -part, so that the soldering-irons can be inserted when this chimney is -put on. If, however, this is not required, but only a strong draught, by -turning the chimney a little, all the openings will be closed. A still -longer chimney can be added at pleasure. A hole should be made at the -level of the grate to admit the nozzle of an ordinary pair of bellows. -This stove you would find of great service, and it may be fed with coke -and charcoal in small lumps. Now you _may_ make the above far more -useful. It will make a regular little furnace, and not burn through, if -you can line it with fireclay. In London and large towns you can obtain -this; and it only needs to be mixed up with water, like mortar, when -you can plaster your stove inside an inch thick or more, making it so -much larger on purpose. There is no need to do this below the level of -the grate; but if you cannot get fireclay, you may do almost as well by -getting a blacklead-meltingpot from any ironfoundry, and boring a few -holes round the bottom for air, and fitting it inside your little iron -stove. In this you can obtain heat enough to melt brass, and it will last -a great deal longer than the iron alone, which will burn through if you -blow the fire much; but for general soldering, tempering small tools, -and so forth, you need not blow the fire, as the hood and chimney will -sufficiently increase the heat. There is no danger in the use of this -little fireplace, but of course you would not stand it near a heap of -shavings, unless you are yourself a very careless young “shaver.” - -[Illustration: Fig. 71.] - - -HOW TO TEMPER TOOLS. - -There is no reason why the young mechanic should not be told how to make -his own tools, and how to harden and temper them, because he ought to be -a sort of jack-of-all-trades; and perhaps he may break a drill or other -small tool just in the middle of some special bit of work, or his drill -may be just a little too small or too large, and there he will be stuck -fast as a pig in a gate, and unable to set himself right again any more -than the noisy squeaker aforesaid. But to a workman a broken drill means -just five minutes’ delay, and all goes on again as merrily as before; and -as we wish to make our young readers workmen and not bunglers, we will -teach them this useful art at once. - -Drills are made of steel wire or rods of various sizes. In old times they -were made square at one end, to fit lathe-chucks or braces, but now, for -lathe-work, they are generally made of round steel, and fastened into the -chuck with a set screw on one side. In this way they can be more easily -made to run true. But there are so many kinds of drills that I suppose I -had better go into the matter a little—only I have not room to say much -more. - -[Illustration: Fig. 72.] - -Look at Fig. 72, and you will see some of the more usual forms of drills -used, but these are by no means all. You will not indeed require such a -collection; and yet, if you should grow from a young mechanic into an -old one, I daresay you will find yourself in possession of several of -them. The first, labelled 1, is the little watchmaker’s drill, of which, -nevertheless, this would be considered a very large size. It is merely -a bit of steel wire, with a brass pulley upon it, formed into a point -at the largest end, and into a drill at the other. The way it is worked -is this: At the side of the table-vice—that is, at the end of its jaws -or chops or chaps—are drilled a few little shallow holes, in which the -watchmaker places the point at the thickest end; the drill-point rests -against the work, which he holds in his left hand. A bow of whalebone, -_a_, has a string of fine gut such as is used for fishing, or, if the -drill is very small, a horse-hair; and this is given one turn round the -brass pulley before the drill is placed in position. The bow is then -moved to and fro, causing the drill to revolve first in one direction and -then in the other. The general work is in thin brass, and therefore these -little tools are sufficiently strong for the purpose. Some of the drills -and broaches (four or five, or even six sided wires of steel) are so fine -that they will bend about like a hair, and yet are so beautifully made -and tempered as to cut steel. - -No. 2 is a larger drill, even now much used. In principle it is exactly -similar to the last, but the pulley is replaced by a bobbin or reel of -wood, made to revolve by a steel bow with a gut string, or a strong -wooden bow. The drills, too, are separate, and fit into a socket at the -bottom of the drill-stock. The large end is pointed, as in the last, -and is made to rest in one of the holes in a steel breast-plate, _b_, -which is tied to the chest of the operator, who, by leaning against -it, keeps the drill to its work, while both hands are free to hold the -latter steady. There is a modification of this tool, invented by a Mr -Freeman, intended to do away with the bow. The bobbin or reel is turned -without raised ends, and is worked by a flat strip of wood covered with -india-rubber, and turned at one end to form a convenient handle. The -having to twist the bow-string round the drill, which is always a bother, -is thus done away with. - -No. 4 is a drill-stock similar to the last, but in place of the -breast-plate a revolving head or handle is put to the top, in which the -point works. This is held in one hand, while the drill-bow is worked by -the other. This is also generally held against the chest, as the hand -alone does not give sufficient pressure. Heavy work, however, cannot well -be done by these breast-drills, and they are liable to cause spitting of -blood from the constant pressure in the region of the heart and lungs. - -No. 3 is the Archimedean drill-stock, now very common, but originally -invented by a workman of Messrs Holtzappffel’s, the eminent lathemakers -of London. It now comes to us as an American drill-stock. It is a long -screw of two or more threads, with a ferule or nut working upon it. The -upper end revolves within the head, which is of wood; the lower end is -formed into a socket to receive the drills, which revolve by sliding the -ferule up and down. Some are 14 inches long, and others not more than 5. -The first are used with the pressure of the chest, the latter with that -of the left hand. For light work these are very useful, and you will -seldom need any other in the models of small engines, &c. - -No. 5 is another watchmaker’s drill, but serves also as a pin-vice to -hold small pieces of wire while being turned or filed in the little -lathes which are used in that trade, and which are worked by a bow with -one hand, while the tool is held in the other. This is by no means a -useless tool, even without the pulley. It is made by taking a round -(or better, an octagon, or five or six sided) piece of steel, drilling -the end a little distance, and then sawing the whole up the middle. The -slit thus made is then filed away to widen it, and leave two jaws at the -end, which grasp the pin or drill; a ring slips over, and keeps the jaws -together. - -We now come to fig. 6, which represents the best of all drills for metal. -It is _really_ American this time, and does our Transatlantic cousins -great credit, as does the machinery generally invented or made by them -(the Wheeler and Wilson sewing-machines for instance). The steel of which -this drill is made is accurately turned in a lathe, and the spiral groove -is cut by machinery. This groove acts in two ways—first, as allowing the -_shavings_ (_not powdery chips_) to escape as the tool penetrates, but -as forming the cutting edges where they (for there are two) meet at the -point. These, however, require a lathe with a self-centring chuck made on -purpose. They are sold in sets upon a stand, chuck and all complete, and -each is one-thirty-second of an inch larger than the other. Some are as -small as a darning-needle, or less, and they run up to an inch or so in -diameter. There are large and small sets. - -We now pass to the old-fashioned smith’s brace, fig. 7, shown in -position, drilling the piece _e_. Pressure is kept up either by a -weighted lever, or by a screw, as shown here. The brace is moved round -by the hand of the workman. Very often this tool is arranged on the -vice-bench, so that the work can be retained in the jaws of the vice -while being drilled. Sometimes it is mounted on a separate stand, having -a stool below, and a special kind of vice or clamp is added. Well made, -this is not so bad a tool as it looks, but those used ordinarily in -smiths’ shops are very clumsy, and do not even run true, and the drills -are badly made, although by sheer force they are driven through the work. - -Whatever form of drill-stock is used, the main thing is to have the -drills properly formed. You will recognise _k_ and _n_ as common forms, -than which _m_ is considerably better. For cast-iron _n_ would not be a -bad point, because the angle is great, much greater, you see, than _k_; -and the bevels which form the cutting edges of a drill should also not be -too sharp, as they are generally made, for, as they only scrape away the -metal, their edges go directly. - -The common way to make a drill is this: A piece of steel wire of the -required size is heated until red hot (never to a _white_ heat, or it -would be spoiled). The end is then flattened out with a hammer, and the -point trimmed with a file. It is then again heated red hot, and dipped -into cold water for a second. Then held where the changes of colour, -which ensue as it cools, can be seen plainly; and as soon as a deep -yellow or first tinge of purple becomes visible, it is entirely cooled -in water. It is then finished, except as regards fitting it to the -drill-stock, which may be done before or after it is hardened, because -care is taken only to dip the extreme point. To get proper cutting -edges the drill is taken to the grindstone, and each side of the point -is slightly bevelled, but in opposite directions, so as to make it cut -both ways. It is not, however, left of equal width, like _o_, but the -flattened sides are ground away, so as to make more of a point, like _p_ -and _n_. - -Now, this is all right enough as regards forging and hardening, and -tempering, and for the _smallest_ drills this is the only way to make -them. (Only watchmakers heat them in the candle till red, and then cool -and temper by running them into the tallow.) But if you want a good -drill that will cut well and truly, you should file away the sides of a -round bar like _m_, only spreading the point very slightly indeed, just -to prevent the drill sticking fast in the work. Another drill, indeed, -is spoken of very highly, which is also carefully made like _m_, but -the places which are here flat are hollowed out or grooved lengthwise, -the section of the point—_i.e._, the appearance of the _end_ of the -drill—becomes rather curious, like _r_. I am assured by those who have -used them, that these cut quite as well as the twist drills which I have -described already. These which I am now speaking of are also American; -and I don’t know how it is, that somehow America is a far better place -for improvements in tools and machines than our own Old England. And if -I had a wonderful invention—a new birch-rod-making and flogging-machine -for very troublesome boys, for instance—I am afraid I should go to -America to patent it; but I daresay English boys would not object to that. - - To teach an idle boy to read, - His mind be sure to jog; - But if he’s very bad indeed, - You’ll be obliged to flog. - - Yet if you flog him day by day, - He’ll _never_ learn to read; - For boys require a lot of play - To make them work with speed. - - But young mechanics, if they err - Or join the lazy team, - Would all, as I suppose, prefer - To be well flogged by steam. - -If not, they had better not let me patent my flogging-machine. Luckily it -is not invented yet. - -The _cutting edges_ of drills come under the same rules as other cutting -edges. You might, for instance, hold a large drill flat on the rest, -and use either edge as a turning-tool. You will see at once that these -edges will not cut if made in the usual way, but only scrape. The bevel -wants to be ground only to 3°, as before explained, to give the proper -clearance, and the cutting edge requires to be then made by grinding back -the _upper_ surface, which is just the same in effect as is produced -by twisting the metal or cutting a spiral groove, which hollows out -this upper surface and gives it cutting power. It is no use grinding a -sharper-looking bevel, or making more of a point—you only weaken the -edge; _m_ or _n_ is quite pointed enough, though the first is a right -angle and the second greater; and, for cast-iron, a rounded point, -showing no angle at all, will do just as well, or better, when once it -has begun to penetrate. Do not be deceived, therefore, by making drills -look pointed and keen, for, I repeat, they are scraping tools only, -unless you file an edge by bevelling back the upper face of each side -of the point. If you were to make a very thick, strong drill, you might -begin by grinding back the two sides to 3°, to form the accidental front -line of the point or section angle, and then grind back, _at 45° from -this line_, the upper face, by which you would do just what you did to -give the graver cutting edges of 60°—only a drill thus formed must have a -point of 90°. It would cut in two directions, like one for a drill stock -and bow. - -I hope my bigger boys will not pass over the remarks on cutting edges -interspersed in this book, for, once understood, they will be found to -be most valuable. Indeed, they cannot work intelligently until they -understand exactly the nature and principles of the tools which they -have to use. In drilling iron, use water or oil, or soap and water, -or soda-water—either will do; but the holes are drilled in the ships’ -armour-plating with soap and water to cool the drill; and very well it -answers, for these plates are several inches thick, but the holes are -soon made. When working in brass and gun-metal, use no water, but work -the drill quite dry. The same rules, in short, apply to drilling as to -turning or planing metal; and if you could see the action of a well-made -American twist-drill, you would recognise this similarity, for you would -see the metal come forth in long, bright curls, as pretty and shining as -those of your favourite young lady or loving sister—_one_ of which you -have, I daresay. - -To give you some idea of what a straight course a drill will take, if -rightly made and skilfully used, I may tell you that a twist-drill has -been run through a lucifer-match from end to end without splitting it; -and as to the _fineness_ possible, I have seen a human hair with an eye -drilled through it, by which, needle-like, it was threaded with the other -end of itself. - -I told you how to bore a cylinder, which is but drilling on a larger -scale, and in Fig. 65 I sketched the method of doing this in the lathe -with a rosebit. But I did not explain another tool used just in the same -way, but which will bore holes in solid iron wonderfully. Fig. 65, L, -H, K, is one of these. This is an engineer’s boring-bit, and is made of -all sizes, from that required to bore the stem of a tobacco-pipe—(don’t -smoke, boys, it will dry up your brains)—to that which would bore a -cannon. A rod of steel is forged with a boss or larger part at one end. -This is centred in the lathe, and the centre-marks are well drilled, and -not merely punched, especially that at the small end. The boss is then -turned quite cylindrical, after which it is filed[4] away exactly to the -diametrical line, as you will see by inspection of L. The end is then -ground off a little slanting, to give, as before, about 3° of clearance. -The cutting edge thus obtained, and the end in which the centre hole -still remains, are carefully hardened. You thus have a tool which will -bore splendidly, but you must give it entrance by turning a recess -first of all in the work, or drilling, with a drill of equal size, a -little way into the material. Used like the rosebit, this tool will run -beautifully straight, so that you can bore very deep, long holes with it, -and cylinders can be most beautifully bored with it. I think you would be -able to make these tools with a little care; but, when you harden them, -only heat and dip the extremities, or it is ten to one your steel rod -will bend and warp in cooling, and you will not be able to rectify it. If -the ends are quite hard, it is as well that the rest should be soft, as -the tool will not then be so liable to get broken. - -There are many other tools used for boring iron and steel, but you need -not trouble yourself at present to learn anything of them—they are no use -to you now. - -I have headed this chapter “Hardening and Tempering” tools, but as yet I -have only partially explained the process, which is a very curious one; -and though the _result_ is highly necessary in many cases, it is by no -means well understood what really takes place in the process, or why this -effect should occur in steel, but not in iron, or brass, or other metals. - -If you heat a piece of bright steel over a clear gas jet or fire which -will not smoke it, you will see several colours arise as the metal -gets hotter and hotter, until finally it becomes red. These are due to -oxidation, which is so long a word that I am not sure I can stop to -explain it thoroughly. Let us see, however, what we can make of it. The -air we breathe contains two gases, oxygen and nitrogen, with a small -proportion of a third called carbonic acid. Neither of these _alone_ will -support life, or keep the fire burning, or enable vegetables to live and -grow, but it is the first which is in this the chief support. The second -is only used by Nature as we use water to brandy, viz., to dilute it and -render it less strong. If we breathed oxygen alone, we should live too -fast, and wear out our bodies in a few hours. If we breathed nitrogen -only, we should die, and so of carbonic acid. Now this oxygen seizes upon -everything in a wonderful and sometimes provoking manner. If you leave a -bright tool out of doors to get damp, down comes our friend oxygen and -rusts it. It combines with the iron and makes oxide of iron, which is -what we call rust. I suppose, however, this oxygen comes more from the -water than the air, because water is made also of two gases, hydrogen and -this same oxygen. It is certain that oxygen in this case always finds any -bright tools that we leave about in the wet, and coats them with a red -jacket very speedily. Then if you look at a blacksmith at work, you will -see scales fall from the hot iron as he hammers it. These are black, but -our old friend has been at work, and united with the red-hot metal and -formed another oxide of iron, called black oxide. We can understand this. -If a man eats a good deal, or drinks a good deal, he gets red in the -face; if he eats till he chokes himself, he gets black in the face, and -I suppose it is much the same when oxygen eats too much iron. Well, when -we begin to heat the steel, down comes oxygen and begins his work; and -first he looks very pale; then he gets more bilious and yellower; then he -gets hotter and shows a tinge of red with the yellow forming orange; then -he begins to get purple, then blue, then deeper blue; and finally black -before he gets absolutely red and white hot. - -Now to temper steel, we first heat it red-hot, not minding these colours, -and then we cool it suddenly in cold water. This renders it very hard -indeed. No file will cut it, or drill penetrate it; but if we strike -it, behold it breaks like glass! This is too hard for general work, -for the edge will break and chip if it meets with any hard spot in the -metal, or chances to bite in too deep. Its teeth are too brittle, and -so get broken off. For this reason we have to “let down,” or temper, -the tool, and we proceed as follows: The part to be tempered is ground -quite bright. It is then laid upon a bar of iron heated red-hot, or -if small, it is held over a gas jet or in a candle; heated, in short, -in any way most suitable and convenient. And now, first, our friend -oxygen puts on a pale yellow face as before. This will do for turning -steel and iron, but is still too hard for general work. Then comes the -orange, and this presently tends slightly to blue; at which point, if -the tool is instantly cooled in water, it will be found to bear a good -edge, hard, but sufficiently tough for work. Most tools for metal and -drills are let down to something between the yellow and blue, and we -know that the more they approach blue, the softer they will be. Thus we -can easily manage our tools;—some to bear hard blows, like axes, which -are tempered to a blue colour; some like files, which a blow will break, -but which are famous for their own special work—these are let down only -to a pale yellow; others, like springs and saws, are let down to a more -thorough blue, because they are required to be elastic and tough, but are -not needed to be so particularly hard. Then tools like turnscrews, and -bradawls, and gimblets are left even softer, sometimes not tempered or -hardened at all, but just forged and ground to the required shape. - -Now, I fancy some of my sharp boys will say that the first description -I gave of the mode of hardening and tempering was not exactly like this; -nor was it, yet in principle it is the same. For instance, if you give -a drill to a smith to make, he will do as I then said. He will heat the -extreme point red-hot, then dip the point in water, give a rub on the -stone or bricks of the forge, and watch the colours. This can be done -when the tool is of sufficient substance to retain heat enough after the -edge has been dipped to _re-heat_ that edge sufficiently. In this case -there is no need to chill the whole tool and then heat it again. But in -the case of small drills and tools, pen-knife-blades, and other articles -of this nature, there will not be sufficient heat retained, after -dipping, to bring up to the surface the desired colours; for oxygen likes -a _hot_ dinner as well as you do, and if the iron is not hot enough he -will have nothing to do with it. - -One great difficulty you would find if you had much tempering to do, -viz., that the articles bend under the operation, some more than others. -Try this: Take a thin knitting-needle when the owner is not looking, and -run off with it;—it is all in the cause of science! Heat it red-hot, -and with a pair of pliers take it up and drop it _sidewise_ in a basin -of water. It will bend like a bow. Heat again, straighten it, re-heat, -and this time pop it in lengthwise—endwise, point first—I mean (don’t -you see that a round needle has _no sides_, and puts me into a perfect -quagmire of difficulty). However, you will understand this, and will -find the needle not bent nearly so much as before, but still it is not -straight. As I explain most things as I go on, I may as well explain -why this bending occurs before I tell you how to straighten your work -again. All metals expand with heat, and contract with cold. I am sure _I_ -contract terribly in the winter until I have had plenty of hot soup, and -hot roast-beef, and plum-pudding; and I know my _temper_ improves, too, -when I get expanded and warm. Well now, when you dropped your sister’s -knitting-needle all hot on its side into the water, that side contracted -before the other, and consequently the needle bent; but when you put -it in the water, _end on_, it was cooled all round at once, and if you -could but cool a piece of metal equally all over, inside and out, _at -once_, all parts would shrink equally fast, and the article would remain -straight. - -But there is, unfortunately, another cause of this bending, which is, -that all articles are not of such form that the same quantity of metal -is on all sides of the axial line. Take a half-round file, for instance; -one side is flat, the other curved, so that taking these two surfaces -into consideration, one contains a great deal more metal than the other, -and will not cool at the same rate. These articles are far more liable to -bend than those whose sides are parallel. Another result of the hot mass -being cooled most quickly on the outside is, that cracks are produced -in the latter, because, so to speak, the skin is contracted, and can no -longer contain all the expanded metal within it. Hence, to make a mandrel -for a lathe, it is common to bore it out first, before hardening, to -remove this mass of metal, and to allow the water to touch it inside as -well as out. Such mandrels seldom crack or bend. - -The only way to straighten articles which have warped by hardening, is -by what is called hacking or hack-hammering, which is nothing more than -hammering the concave or hollow side with the edge of the steel pane of a -hammer. This spreads the metal upon the hammered side, and, by expanding -it, straightens the tool, for the hollow side, remember, is that which -was too much shrunk or contracted. This is not an operation you will have -to do, especially if you only harden the extreme points of the drills and -little tools you make. - -There is another way of hardening, not steel, but iron, called “case -hardening,” because it puts a case of steel over the surface of the -metal. Obtain a salt called prussiate of potash. It is yellow, like -barley-sugar, but is poison. Heat the iron red-hot, and well rub it upon -this salt, and then cool it in water. You will find that now a file will -not touch it, its surface being as hard as glass. It is carbonised on its -exterior, and made into hard steel. This can be done in another way, as -gun-locks, snuffers, and many other things are case hardened. They are -enclosed in an iron box, with cuttings of leather and bone-dust, and -the box is luted about with clay and put in the fire. All the pieces get -red-hot, and the leather chars and blackens, and some of it combines as -before with the hot iron, and makes it into steel. And our friend oxygen -is considerably at a loss in this case to find his way in, or he would -make black scales again and spoil the work; or combine with the carbon -(or charcoal) and make it into gas. Probably, however, as we shut up a -little oxygen with the contents of the box, this change DOES take place, -but _just as the gas rises the iron seizes it_, and holds it fast. - -And now, boys, I find it necessary to lay down the pen, which I see has -almost run away with me, and written a good many more pages than I at -first intended. Since I began to write I have visited the workshops at -King’s College, and seen a sight to gladden my eyes. Boys carpentering, -boys turning, boys filing; engines of real use, with single and double -cylinders, finished, and in course of construction, and all these the -work of schoolboys, whose hands and brains are alike engaged in this -delightful branch of industry. Let no one, therefore, pretend that -boys are not capable of executing good work of this kind in a masterly -manner, or that what they do is always child’s-play, or I shall take -up the cudgels in their behalf. I have also seen, in the Working-Men’s -Exhibition, a very neat little engine, made by a boy only twelve years of -age, which makes me hope and believe that the few hints upon wood and -metal work which I have here thrown together will neither be unacceptable -nor useless to those whom I address in these pages. In this hope I take -my leave, and sign myself, with gratification and pride— - - The boy mechanic’s faithful friend, - - THE AUTHOR. - - - - -FOOTNOTES - - -[1] In the drawing, they are all accidentally drawn of the same pitch. - -[2] The parts so jointed are highly exaggerated; when hammered down, the -joint only forms a light beading. - -[3] The bottom joint must therefore be hammered close; the upper one will -become a ledge for the boiler to rest on. - -[4] In large tools this is not done by the file. - - - - -Heroes of the Nations. - -EDITED BY - -EVELYN ABBOTT, M.A., FELLOW OF BALLIOL COLLEGE, OXFORD. - - -A series of biographical studies of the lives and work of a number of -representative historical characters about whom have gathered the great -traditions of the Nations to which they belonged, and who have been -accepted, in many instances, as types of the several National ideals. -With the life of each typical character will be presented a picture of -the National conditions surrounding him during his career. - -The narratives are the work of writers who are recognized authorities on -their several subjects, and, while thoroughly trustworthy as history, -will present picturesque and dramatic “stories” of the Men and of the -events connected with them. - -To the Life of each “Hero” will be given one duodecimo volume, handsomely -printed in large type, provided with maps and adequately illustrated -according to the special requirements of the several subjects. 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FREEMAN, D.C.L., LL.D., Regius Prof. of History in the - University of Oxford. - - =Alfred the Great, and the First Kingdom in England.= By F. - YORK POWELL, M.A., Senior Student of Christ Church College, - Oxford. - - =Charles the Bold, and the Attempt to Found a Middle Kingdom.= - By R. LODGE, M.A., Fellow of Brasenose College, Oxford. - - =John Calvin, the Hero of the French Protestants.= By OWEN H. - EDWARDS, Fellow of Lincoln College, Oxford. - - =Oliver Cromwell, and the Rule of the Puritans in England.= By - CHARLES FIRTH, Balliol College, Oxford. - - =Marlborough, and England as a Military Power.= By C. W. V. - OMAN, A.M., Fellow of All Souls College, Oxford. - - G. P. 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