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

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.