Gouges for turning are made in all sizes, having cutting edges from one-eighth to two inches. The sectional form varies from crescent-shaped tools, with a thick back tapering to a thin edge, to circular ones, in which back and edge are of equal thickness. The curvature of the tools varies also greatly: from those in which it is so slight that they may almost be considered straight-edged to others having a semicircular edge. The length of gouges is partly governed by their size, one inch gouges measuring generally from ten to fifteen inches long.
The ordinary gouge and chisel used by the wood-turner must not be confounded with those tools having the same names but used in cabinet making and joinery. The carpenter’s and the turner’s gouges are quite distinct tools, though they have a general similarity; and the same may be said of the chisels used in the respective trades. The turner’s gouge is a much stronger tool, having more metal in it than its namesake; it is ground to a different shape, and has a handle from eight to sixteen inches in length, according to the size of the gouge. Fig. 14 illustrates a gouge handled complete. Both tools are ground on the outside of the curvature, but the turner’s gouge terminates in a rounding edge, without corners, instead of being square with the shaft of the tool. This round form of edge is necessary in order to obliterate the sharp corners, which would be liable to catch in the work. It also allows the most prominent parts of the edge to be used in grooves which are comparatively narrow. Very small curves and mouldings can thus be easily operated upon by small gouges.
Fig. 14. A TURNER’S GOUGE.
Several sizes are always provided for use, and whilst the larger ones take off large shavings and rough the material to shape quickly, the small ones are available for more minute work, and may be used for turning in shoulders to very nearly an acute angle.
Chisels for turning are made in sizes to correspond with the gouges, but larger ones can also be procured. They resemble ordinary paring chisels, but have no shoulder to the tang, the edge being also formed very differently. The blade of a turner’s chisel is bevelled equally from each side, leaving the cutting edge in the centre of the thickness and at an oblique angle with the sides. This angle is usually about seventy degrees and one hundred and ten degrees, instead of being square across like a paring chisel. Turning chisels are ground obliquely, for the sake of greater convenience in use. One of ordinary shape performs the work equally well, but, as that tool has to be applied at an angle to the work, which is often inconvenient, an oblique edge is preferable, allowing, as it does, a cylinder to be turned with the tool at right angles to the axis of rotation.
The method is the same for applying both gouges and chisels. The tool is grasped firmly near the cutting edge by the left hand, the knuckles being uppermost. The right hand holds the handle near the end, and, to afford greater steadiness, it usually rests against the side of the body. Thus held, the tool, if a gouge, is laid on the T-rest with its convex side downwards. The edge is brought sufficiently near to the revolving cylinder to touch it in the position of a tangent; that is to say, a straight line, drawn in continuation of the ground bevel of the tool, will touch, but not cut into, the cylinder. In this position the gouge will not cut, but by raising the end of the handle with the right hand, the edge of the tool is depressed, and it then comes in the position of a tangent to a smaller circle. When the work is rotated, all the material outside of that diameter will be shaved off by the tool. During this process the pressure on the edge of the gouge tends to force the tool deeper into the work; the right hand must, therefore, hold down the handle till the work has been reduced all round to the new diameter.
The first cut of the gouge is usually made at a short distance from the right-hand end of the rough balk, and when a groove is turned the tool is inclined towards the left, so as to remove the material between it and the end. A new cut is then made towards the left, and this is made continuous with the previous one by inclining the point of the gouge as before; thus by a continual shifting of the tool, and turning a small distance at a time, the entire cylinder is brought roughly to form. The size is gauged by means of callipers, and if much in excess of what is required a further application of the gouge is the best way of reducing it; and the cylinder is made as straight and even as possible by this tool before employing the chisel. In this levelling operation the gouge is slid along the top of the T-rest, guided by the left hand, and tracing on the work a regular spiral path. An expert hand can by this means produce a very tolerable smooth surface to the work, the gouge being traversed from both ends alternately, and the parallelism is checked by callipering.
The chisel used for smoothing the work is applied similarly to the gouge, and all that has been said applies to both tools, subject to any modifications rendered necessary by their different forms. The chisel is always applied so that its edge lies obliquely across the surface of the cylinder, the handle being also slightly inclined to place the edge of the chisel—which is, as has been already stated, ground obliquely—at a slightly greater angle with the line of centres than that it makes with the chisel blade. The tool is land on the rest, with the blade resting on one corner of the obtuse angle. The chisel is tilted up sufficiently to bring the central part of the cutting edge against the work. Only the central part touches, both corners being free, the edge lying obliquely across the cylinder. If either corner were allowed to act on the work it would be extremely difficult to guide the tool, which would have a tendency to “catch in.” This tool is held with the left hand grasping the blade close to its cutting end, with the knuckles above; the right hand grasps the handle near to its end, holding it near to the right hip, and the chisel blade rests on the T, one of its lower corners only in contact. The tool is slid along with the obtuse angle leading, and may be used from either right or left. To reverse the direction it is only necessary to turn over the tool.
Through the tool being presented with its edge obliquely, only the central part cuts, the two corners not coming in contact with the work, and the extreme central part cuts deepest, the shaving cut by the chisel being thickest in the centre and tapering off on each side to a feather-edge. By carefully considering this, the necessity of correct tangential position will be better understood. If the chisel is laid on to cut with the entire breadth of its edge, the tool becomes unmanageable from the quantity of material it has to cut. The production of straight, level work will depend on maintaining, during the entire longitudinal traverse of the tool, a perfectly equal amount of tilting from the T, and the same relative position of the handle held in the right hand. It must be remembered that the chisel lying obliquely across the surface of the cylinder, and forming a tangent to it, will not cut at all, acting just as a gouge under the same conditions; but directly the handle is raised, and the edge penetrates the diameter, then the tool lies at a tangent to a circle of smaller diameter, and all material outside of that circle will be cut off. The cut is taken from either end, as most convenient, by simply turning over the tool. The principles which govern the cutting action of the gouge are equally applicable to the chisel, and it is by tilting up the handle that the tool is fed into the cut.
Fig. 15 represents a gouge of the form in general use; it measures nearly half-an-inch on the edge. The section shows much less metal than is embodied in Fig. 17, and this kind of gouge is much lighter and handier in many respects than the one shown at Fig. 17. The grinding is more easily accomplished. The substance of the tool is quite adequate to the requirements of all ordinary wood-turning, and it is with gouges of this form that most work is done. Larger sizes, from one inch to one-and-a-half inches, are used for roughing-down purposes. The section of this tool is crescent-shaped; the centres of the two circles, whose arcs form the concave and convex sides, are about one-sixteenth of an inch apart. The points of the horns are rounded off, so that all sharp corners are avoided. The convex surface has a radius of a quarter