Centre punches consist of two principal classes, named dotting punches and coning punches. Dotting punches are made of small steel wire, not exceeding a quarter of an inch in thickness, and are used for making dots to indicate the places of centres in sides and ends of various pieces of work ; they are used also for making dotted lines to indicate the place of a line or other mark which is liable to be rubbed out or filed out. All dotting punches or dotters require to be sharply pointed and applied with a small hammer, because the dot which is formed should be only large enough to be seen whenever it is necessary to refer to it. A dotter is shown by Fig. 269, the angle of the dotting part being about forty degrees.

Coning punches are of various sizes from half an inch to one inch in thickness, some being held in one hand while in use, and others being attached to handles, if the punches are driven into the work by means of heavy blows. Coning punches are represented by Figs. 270 and 271, and are required to make or enlarge conical recesses in work which is to be lathe-turned. For this purpose, the piece of work to be turned is properly lined, and small holes are drilled at the centres of the intended conical recesses; after this, the recess is formed by widening the mouth of the small hole with a larger drill, or sometimes with a chisel; and when roughly shaped, the coning punch is hammered into the recess, to make it smooth, and give it the proper conical form.