I and K show the edge and side of a parting tool for cutting off the ends of cylindrical pieces, separating the turned from the unturned parts, and for all similar work. [A tenon-saw held still against a piece revolving in the lathe will often serve to cut it in two, but parting tools must also be had, and two are better than one, as a thick one should be kept for common woods, and a thin one for ivory and precious materials; sometimes one with a notched edge is used for cutting off soft wood.]
L to O are for turning iron and steel. The first is a graver, of which all sizes are made; one of a quarter inch width on either face is large enough. It is a square bar of steel ground off cornerwise so as to form a lozenge-shaped face. This is an essential tool for iron, and will do all sorts of work.
M is a hook or heel tool, made sometimes with a flat edge and sometimes with a rounded one, the latter being most useful. It is a very powerful tool, much used by some, especially for heavy work—I don’t think you need get one at present. If I am able to teach you to use a graver it will do almost as much work, and is a neater tool. If you use a tool of the nature of heel-tools at all, I think, on the whole, the nail-head tool, N, either round or square, is the best. It is at all events handy for roughing down work, and when it is reduced nearly to the size required, and is partly smoothed, the graver will finish it.
O is an inside tool for hollowing out iron. There are different shapes of this used, each turner giving the preference to some particular pattern to which he has habituated himself. None of these tools for metal have sharp edges—at least they would not appear so to an ordinary observer. The angle of the edge is 60° to 80°, or even 90°, which is, as you know, a right angle, and is that most generally used for the cutting edges of tools intended for brass, as U, V, W, of which V is a most useful pattern. Those for hard wood have edges a little more keen, but after all they scrape rather than cut; the only tools for wood with keen edges being the gouge and chisel.
P are callipers for measuring the outside of work of all kinds. Q and R are the same, arranged for in and outside work. The first is an ordinary pair closed until the ends have crossed, which they will all do; but if the inside of hollow work to be gauged is small, they will not enter it. In this case none are so generally useful as the in-and-out callipers, R, for when accurately made (and if not you can easily correct them with a small file), the one end will measure the external diameter of work, and at the same time the other end will be found to have its points separated to such a distance, that if you were to turn a box or chuck to this inside measure, the cylinder first turned will exactly fit it. Thus if you turn a box-cover, and take the size of it with the straight end of the callipers, and then turn down the rim of the box until it is just the size indicated by the curved ends, the one will exactly fit the other. In turning a piston to fit the cylinder of an engine, you would work with this useful tool.
S is the turner’s square. The blade slides stiffly and accurately in a slot in the brass, being kept by a spring at one side from working loose. This square is used to gauge the depth of boxes and other works which are to be turned to an exact size, and it also serves to test the squareness of many kinds of work. Suppose, for instance, you had turned a box, you would put the blade of this tool against the bottom and press upon it till the brass rested across the rim, touching it in two opposite places. Now possibly the inside may be smaller at the bottom than at the top. Test it by bringing the steel blade edgewise against it. You will see whether the brass still touches in two places across the mouth of the box. The squareness of the outside with the top or bottom can be tested in a similar way. We shall have occasion to recur to this when we come to boring and fitting engine cylinders.
S² is another small square, which is often serviceable where the carpenter’s square cannot be used. If you intend to make models, you will want both of these; at the same time, it is quite possible to make the latter of iron, or even thick tin, if you have the former, as an accurate guide to work by.
T represents a pair of spring-compasses or callipers. They are used to set off distances, and have the advantage of not being liable to shift their position when once they are set to any required width. You will require a pair of compasses of some sort, and if not already provided, these are the best you can have.
There are many other tools, which, though not absolutely turning tools, are more or less used in connection with the lathe, but these need not now be further alluded to, and I shall go on to describe as clearly as possible the method of working at the lathe with hand-tools, commencing with the operation of turning soft wood with the gouge and chisel; but I must first give a short chapter upon the nature of woods used.