IT will now be as well to fulfil a promise made in one of the earlier pages of this work, by describing the proper method of making a chuck in wood and in metal, because this is a task almost necessary for the amateur, and involves a little screw-cutting, in which he is now supposed to be fairly proficient. To commence with a plain cup chuck of boxwood. Let a piece be sawn from the log, of adequate size, say 2 ½in. or 3in. in diameter by 3in. in length; care must be taken to saw it off squarely, or there will be unnecessary waste, and boxwood is precious. If a self-centreing scroll chuck is at hand that will grasp it, nothing can be more suitable. If not, let a hole be bored centrally, and mount the block on the taper screw chuck. It must bed down fair and true against the plate of the chuck, and be very firmly secured, because it has to stand both turning and boring. Bring up the back centre to help hold it, while the outside is being reduced to a cylindrical surface, and the end cut exactly square to the axis. Of course you can, in this last operation, only carry the cut as far as to the back centre. The poppet head must, therefore, now be removed, and the face of the work finished by means of a chisel, held flat on the rest as before explained; try it with a straightedge, and see that it is neither hollow nor convex, but truly flat. Now, with a nose bit or gouge, or round-end tool, bore a hole to a depth rather greater than the length of the screw on the mandrel nose; and if the latter is lin. diameter, let this hole be7/8 in., as the thread will be, probably, 1/8in. deep; anyhow, don't let it be too large, as it is easy to enlarge it if too small. Here, again, care is needed to prevent the bore from being conical in either direction - it must be quite parallel. An inside tool, or right-hand tool, as it is often called, is the proper one to finish it with. Now bevel slightly, or round off the sharp edge, or "arris," as directed in the chapter on screw-cutting by hand, which is the next process to carry out; but, unless the turner is an adept at screw-cutting, he had better avail himself of some kind of guide - a traversing mandrel, if he has one; but if not, the best way is to use a special tap, made to cut sharply, so as to make a screw line deep enough to give a lead to the chasing tool. The sort of tap to have is one similar to what is sold with a screw-box. The taps for metal are of no use for this work. The ordinary taper tap will not get a hold, unless you can make the hole a deep one; the plug will not enter, and the intermediate will not have sharp cutting threads near its end. What is needed, and should be sold always with a lathe, is a very short tap, with four sharp edges, and a long stem with a hollow centre made in the end; the cutting part must, of course, taper a little. It is certainly possible to use an ordinary intermediate tap for a cup chuck, because you may bore it as deep as you please; but it is not really suitable. The way to enter it is to bring up the poppet head so that its point may fall into the hollow centre in the end of the stem or shank, a small spanner or hand vice being secured to the square head of the tap, or a proper tap wrench, which is better. The tap is then slowly revolved, a little at a time, while the back centre is screwed up so as to follow it; and this is carried on until the requisite depth is reached. There will now be, on gently withdrawing the tap, by turning it backwards, a clear, sharply-cut screw line, quite sufficient to give a lead to the chaser - and it will be parallel, and true to the lathe centres. The hand rest is now to be set across the end of the chuck, and the inside screw tool is to be gently applied, when its points will be caught at once in the spiral groove, which will carry it forward at the required rate. In this way the thread is to be deepened gradually, until it is found to be of full depth, and equally cut from end to end of the hole.

To allow of this, it is usual to bore a little deeper than the length of the mandrel nose, and then to take a side parting tool, and with it to cut a groove at the bottom the full depth of the thread. The chaser will then fall partly into this, giving time to withdraw its teeth out of cut, and thus enabling it to cut to the end of the thread without striking the bottom of the hole. Now unscrew the chuck (not the one you are engaged upon), and, turning the latter round, try how it will go on. If it is too tight, do not force it, but put all back, and ease it. The sharp edge of the thread will be better removed, and a chuck should run on quite easily, and bed up well and truly against the face of the mandrel. Try and try again, therefore, until such is the case. All that remains is to screw the wooden chuck in its place on the mandrel, turn up the outside, and bore it out to the size needed; which latter job should be left, of course, until the chuck is actually required for use. It is usual to round off and shape to a nice curve the back end of the chuck, next to the mandrel; but this is a matter of taste. If all has been well done in boring and screwing, the chuck ought, theoretically, to run true at once, when in its place; but this is seldom the case, although the error is often very slight. In any case, a few strokes of gouge and chisel are all that will be needed, and, once true, it will generally so remain for a long time.

To make a similar chuck in metal, the process, roughly speaking, is the same; but here we have to deal with a casting of iron, brass, or gunmetal. This must, of course, be chucked differently, though if of brass, a strong American scroll chuck may possibly suffice; yet it is hardly a safe plan. Preferably I would chuck it upon - i.e., outside - a wood chuck, or outside a block of wood driven into a metal cup chuck, and turned to fit it tightly. If it is a good casting, and is mounted to run fairly true, there will be no shocks caused by the tool, even at the first cut - only a steady strain, that should not loosen it, or throw it out of centre. The skin should he ground or worked off with a coarse old file before mounting it on the lathe, as it will make it much easier for the tool to face it up. Such skin is often exceedingly hard, and will instantly take off the edge of a tool; the latter, however, should always have a clean place to start upon, by filing off the edge of the work to form a slight bevel - it then gets at once underneath the skin. There are face-plate clamps which will also serve our purpose, but on the whole the plan suggested will be the simplest, and therefore the best. The chuck to be turned need not occupy more than an inch of the block on which it is mounted, if it is well fitted. Being rough inside, it will take a secure hold of the wood. The great thing is to drive it on carefully and truly at once, so as not to have to keep on tapping it this way and that, to set it correctly, or it will be loose on the block, and yield to the tool. Supposing the work fairly mounted, a cut should be taken, all over it, either by hand, or, better, by a tool in the slide-rest; a round-end will be the usual one. Then, the end that has to be bored is to be very truly faced; and, if the hole is not cored out in the casting, it will have to be drilled - and in a cup chuck it is generally drilled quite through into the hollow of the chuck. It is not easy to make a 3in. chuck solely by hand, but as regards boring out the hole for the screw no turning is necessary. If not cored out, a little centre hole is first made, by the point of a graver, and then a drill is run in, and the bore enlarged by another; or a little recess is turned, and then a half-round engineer's bit of the exact size needed, bores and completes the hole at one operation. This tool has a centre drilled at its opposite end, and is always advanced into cut by the screw of the back centre. It is a splendid tool if well made, and will cut a clean hole in solid iron; but it will save it to run a drill in first. You must turn a slight recess, however, just to insure a true start. The tap now comes into operation as before, and here again it needs one made sharp to cut a clean line, but a tap a good deal less in size than the mandrel nose, as it will be followed by the chaser, as in the case of the wood chuck. The chief thing is to keep the tap in line with the mandrel, and this is secured always by advancing it by means of the back poppet centre.

All taps of the size of a lathe mandrel have centres left, and are so used' in lathe-work. Generally speaking, the screw on the mandrel is not cut clean up to the shoulder against which the chucks abut, and therefore, after finishing the screw to a nice fit as far as it will go, two or three threads must be turned off. It will then bed correctly home, and also run fairly true. As soon as it does this, finish the outside while it is in its place, and, if you like, turn the inside out quite smooth, and very slightly taper - so slightly as to leave it almost cylindrical. Such is the proper, orthodox, and best way; but a great many chucks are mounted in the lathe and bored, and then, if a through or thoroughfare hole is allowable, as in the present case, the entire thread is done with ordinary taps, and the chaser wholly dispensed with. It is then screwed on the mandrel; and, as it is rarely that it can run true, the outside is freely cut away to make it run correctly. If the end does not touch the shoulder of the mandrel all round, it is filed till it does, and the result is a badly-fitted chuck, that will again and again work out of truth.