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 James Lukin

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in section at L. This allows the narrowest of the hooked tools to be applied to under-cut the solid core x. This being withdrawn, a rather longer hook is applied, the hook being held downwards as at O, until it reaches the spot where it is to work, when it is gradually turned up (bevel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.