Fig. 15. A HALF-INCH GOUGE.
The accompanying cut, Fig. 16, shows three views of the cutting end of a turner’s gouge, and are intended to illustrate the method of grinding. C is the front, or concave side, of the gouge, and shows the parabolic curve of the cutting-edge. B is the side, and shows the long sloping chamfer made by grinding the tool. The angle formed by this chamfer should be from twenty-five to thirty degrees. It is this chamfer that should form a tangent to the work when the gouge is in use. A shows the back, or convex side, of the gouge, and the chamfer will be seen to be of equal slope all round. In setting gouges, the turner has an ordinary oil-stone, with a number of different-sized, semi-circular groves worn into it. A groove the size of the gouge is selected, the back or chamfer part rubbed along it, at the same time turning the tool slightly, as when grinding. Then with a slip of oil-stone having a rounded edge, the wire-edge, which will be found all round the cutting edge in the hollow side, is removed. In doing this great care must be taken to rub the burr down only level with the surface on the hollow side, because tilting up the back end of the slip would produce a slight chamfer on the hollow side of the tool, and this is not desirable. The operation, however, turns the wire-edge backwards, when the tool must again be lightly applied to the hollow set-stone; and, finally, one or two more rubs on the inside with the slip, after which it is wiped with a piece of soft leather, or on the palm of the hand, which removes any remaining wire-edge, and the tool is now ready for work. All the gouges, large and small, are ground and set as described above, different-sized slips being used.
Fig. 16. GRINDING A GOUGE.
Fig. 17 shows a quarter-inch gouge. Top, side, and sectional views being given, the small semi-circle shows the size and form of the cutting-edge. This kind of gouge is particularly strong, as can be seen from the sectional view, there is only a small channel as compared with the substance of the tool. The bevel formed by grinding is shown in the side view; and the form of the point, seen from the top, illustrates the correct form for grinding. There are no sharp angles, the point ends in an elliptical edge, leaving the centre most prominent. The horns of the crescent-shaped section are thinned off on their outer sides, to save metal and leave less to be ground away. Both the inside and the outside curves are circular, excepting the part just alluded to; the centre of the smaller circle is, however, fully a sixteenth of an inch from the centre of the convex face.
Fig. 17. A QUARTER INCH GOUGE.
Fig. 18 represents a three-quarter inch chisel; side, top and end views are given. The two bevels, which meet at the cutting-edge, enclose an angle of twenty-five degrees. This, as will be seen by the diagram, Fig. 13, is the angle suited for wood-turning tools. The oblique edge forms at each corner angles of seventy degrees and one hundred and ten degrees respectively, as has been mentioned previously. A chisel of the size illustrated will measure from about eighteen to twenty inches from end to end, when handled ready for use, the blade being about half that length. The rectangular figure, facing the cutting-edge, is a view of the end.
Fig. 18. A THREE-QUARTER INCH CHISEL.
Fig. 19 illustrates a hook-tool used for turning interior hollows. The steel shaft is forged out thin and wide at the end, and curled into a circular form as shown. The outer part of the circle is ground square with the tang; the inner side is thick in the centre and bevelled towards both edges. This makes a sharp cutting-edge around the ring, as shown in the top view. The tang itself is square in section, with the corners bevelled off; near to where the hook commences it is nearly round. These hook-tools are carefully filed round the inside to form a smooth bevel; all the corners are rounded off, and the tool is then hardened and tempered for use. It may be applied to the work either side up, and considerable manual dexterity is required in its use to prevent accidents of a more or less serious nature.
Fig. 19. A HOOK TOOL.
The other necessary tools for ordinary wood-turning are but few, and consist of callipers, a pair of compasses, two or three slips of oil-stone for setting up the gouges, a side tool and a parting tool. Fig. 20 shows a large scale view of the side and edge of an ordinary parting tool. A grindstone and an oil-stone are also very useful, and, in practice, the use of these cannot well be dispensed with. There should be about half-a-dozen pairs of callipers of various sizes, the largest opening to about twelve inches to fourteen inches. Also one or two pairs of inside callipers, these being too well known to need illustration.
Fig. 20. PARTING TOOL.
The parting tool is in shape like Fig. 20, about five-eighths of an inch broad and one-eighth of an inch thick. It is used for cutting off pieces of finished work from the block, held in the cup chuck, or on a face plate, such as bosses, patellas, draught-men, &c. It works best when the grain of the wood is running at right angles to the lathe centres, that is plankways.
The above tools are about sufficient for most purposes. There are, however, a variety of other tools of peculiar forms required by turners who do a great variety of work. The shape of these suggest themselves from the nature of the work to be done. Old files of various forms are often utilised by grinding into the required form. In the grinding of all tools, see that the ground part, or chamfer, is a straight line from the heel to the cutting-edge; and in setting on the stone this surface should lie nearly close on the stone, the heel only slightly raised, so that the cutting-edge comes in contact with the stone. If the handle end is held much higher, a new chamfer is immediately formed at a more obtuse angle than the ground part, and the tool will not work satisfactorily until it is re-ground.
The first actual turning is done with the gouge, and large ones are used for large rough work. The correct angle for grinding the gouge, and the proportion of handle have been previously mentioned. The rest is placed just clear of the revolving work, and the T adjusted to a convenient height, so that when the cutting-edge is performing properly, and the tool resting on the top of the T, the handle will come to a convenient place at the right-hand side. The height of the rest is therefore generally to a certain extent governed by the stature and habit of the workman.
CHAPTER III.
ROUNDING TOOLS AND MACHINES.
THIS chapter deals with the tools used for producing plain cylindrical work, such as curtain poles, broom-handles, dowel-pins, &c. A large quantity of cylindrical wood is used in many ways other than for the purposes named, but it would be of little use even to attempt to enumerate