The Parting-tool, shown in Fig. 12, is used for cutting off finished work. It has, however, a greater use, in conjunction with the calipers, in regulating the outline of work, by making a narrow groove that will have a diameter at the bottom equal to some principal dimension of the work, and to which the general outline will, later, be reduced. The seventh exercise involves this use of the parting-tool. Its size is determined by the width of its cutting edge.

Fig. 12.