Chapter X.—CUTTING TOOLS FOR LATHES.
The cutting tools for lathes are composed of a fine grain of cast steel termed “tool-steel,” and are made hard, to enable them to cut, by heating them to a red heat and dipping them in water, and subsequently reheating them to temper them or lower their degree of hardness, which is necessary for weak tools.
These cutting tools may be divided into two principal classes, viz., slide rest tools, or those held in the slide rest, and hand tools, which are held by hand.
The latter, however, have lost most of their former importance in the practice of the machine shop, by reason of the employment of self-acting lathes.
The proper shape for lathe slide rest tools depends upon—
1st. The kind of metal to be cut.
2nd. Upon the amount of metal to be cut off.
3rd. Upon the purpose of the cut, as whether to rough out or to finish the surface.
4th. Upon the degree of hardness of the metal to be cut.