All the hardwood and ivory turning tools handled in short handles, are presented to the work radially and about horizontally, fig. 408, their under surface lying either nearly, or else quite flat upon the rest. To place the face of the tool both precisely radial and horizontal, the rest would necessarily require raising or lowering to accommodate the thickness of every individual tool. Practically, this is not done; the rest is adjusted to a suitable height for a tool of average thickness, when that for the moment in use, fig. 408, sufficiently approaches the cutting position, if the handle be held slightly more or less above the horizontal line. For convenience of explanation however, the hardwood and ivory tools, may be said to be held in the horizontal position.
The handle of the tool is grasped in the right hand, with the forefinger and thumb stretched out along the blade, the under side of the thumb pressed on the face, and the inner side of the forefinger against the right side of the tool. The whole of the fingers of the left hand are passed around the pedestal of the rest, and the left thumb, pointing upwards, is pressed against the left side of the tool, opposite the end of the forefinger upon its right. The tool is thus held cushioned between the thumb and forefinger, pressed on the rest by the right thumb; its lateral traverse in either direction being under perfect control by the pressure of the thumb or finger on the one side, and their gradual yielding on the other. The gouge and chisel are often held as upon softwood, but usually upon hardwood, and almost invariably upon ivory, they are used in the horizontal manner; that is to say, the hands hold the tools and the rest in the manner just described, but they present the tools to the work with their shafts at the vertical inclination, necessary as alreacty explained, to cause their cutting bevils to lie as tangents to the cylinder.
During the deep separate cuts, used to reduce the work to shape, or in surfacing, with any of the hardwood tools figured in this chapter, and held in the horizontal manner, the upper arms are kept in close contact with the body, all braced stiffly together with the tool. The latter is firmly pressed on the rest, and is advanced to penetrate the work by the weight of the body moderately brought to bear upon it, or by lowering the handle to exert its leverage upon the edge. In cutting the subsequent lighter continuous shavings, the tool is traversed along the rest by gently swaying the body in the direction travelled; the arms still in contact, but all the body held much less stiffly, a little independent motion being allowed to the wrists and elbows to aid the equal traverse of the tool. For lighter and for precise cutting, and in sweeping the tool around small curves, the right arm may be held free of the body, and the left upper arm only in light contact. The tool may then be moved by the right wrist alone, and works upon the left thumb as on a center, or slides upon it as a stop, or sometimes, the left thumb pressed against the tool advances with it.
A few of the larger flat tools, parting, point, round and right side tools, used for heavy, and for large or deep internal work, require the additional command of the long handle. They are held with the left hand wrapped around the blade, the fingers underneath, the right hand towards the end of the handle, sufficiently high up against the side to cause the shaft of the tool to lie nearly horizontally upon the rest. The larger sizes of the short handled tools are sometimes held after the same manner; the right hand at the end of the handle, is then placed against the right chest, the arm pressed against the side. The size of the tool and its handle and the manner in which it is held, are greatly determined by the magnitude of the work. Large and strong tools are used to rough out the work nearly to shape, leaving but little material to be removed by the lesser and thinner tools, then suitably employed to perfect and finish the surfaces. Too slight a tool used for heavy cutting is inefficient and acquires vibration, it is then difficult to produce a smooth surface; but the use of the slighter, narrow tool, required for small work, is sometimes unavoidable for those portions of large works that will not admit the width of the larger tools.
The tools cutting upon their ends, fig. 408, being generally-presented to the work with their shafts at a small vertical angle, cutting action may be obtained both by simple pressure, or by lowering the handle, with the latter, leverage alone causes the edge to penetrate. The latter force however, may be readily applied in excess, to the damage of the work. The rest is placed so much closer to the work in hardwood turning, that comparatively a much less portion of the tool overhangs it, so that the leverage of the short handled tools for hardwood, is frequently still greater than that of the long handled softwood tools, previously referred to.
The side cutting tools are usually held slightly tilted upon their left under corner, their faces therefore being at a small vertical angle to the surface upon which they are cutting; leverage is obtained by slightly twisting the shaft upon itself, from left to right. The penetration then depends upon the amount of vertical angle of the face, when the cutting edge is placed in contact with the work, together with the amount of twist given to the shaft; which produces precisely the same effect, as the inclination of the shaft and the subsequent lowering of the handle, of the tools cutting by their ends.
The cutting action may be said to be nearly always obtained by some amount of pressure; but leverage so greatly assists direction, that alteration in the vertical angle of the shaft, either at the commencement or during the progress of the cut, is rarely altogether absent. In the heavier roughing cuts leverage preponderates, sometimes it is alone used; while in the last finishing cuts, the tool as a scraper receives only gentle pressure. The proportion in which the two forces combine, running almost in a regular progression, of more pressure and less leverage, as the work advances from the rough to the finished stages. The application of the hardwood and ivory tools is so similar, that with the mention of some peculiarities, the descriptions given in the following pages, will serve equally well for either material.