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.
Fig. 51.