Read Ebook: 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 Lukin James

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CHAP. PAGE

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 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.

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 28 1/2 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 .

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 .

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.

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.

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.

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 11 1/4 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 5 1/4 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 5 3/4 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.

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 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.

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.

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.

I have not here put any feeding-boxes, or seed-drawers, because glasses are the best; but you will see two holes , 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 . 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.

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--

MORTICE-GAUGE.--The use of this will be shown presently.

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 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.

The width of the board I set down at 4 inches, because the rails, when finished, will be 1 1/4 inches each, or, in all, 3 3/4 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 1 1/4 inches, and two eighths, or a quarter of an inch, to spare for waste. Take the compasses, therefore, and open them to 1 1/4 and a little over , and take it off at each end of the board .

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.

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.

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 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.

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.

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.

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.

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 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.

I have told you to cut the side and end pieces 18 inches and 2 feet 9 respectively, so that if the mortices are 1 1/2 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 , 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.

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.

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 .

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.

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.

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.

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.

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 . 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.

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.

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