This section is from the book "An Elementary Outline Of Mechanical Processes", by G. W. Danforth. Also available from Amazon: An elementary outline of mechanical processes.
Lathe centers must be accurately pointed to an angle of G0°. They must be kept sharp-pointed, smooth, and absolutely free from grit or metal chips.
A bar to be suspended in the lathe must be centered as shown in Fig. 177. The center of each of the round ends of the bar is located by means of dividers or otherwise, marked with a center punch, drilled to a depth of about half an inch or more, and countersunk to fit the taper of the lathe center. The end may be recessed to insure protection to the countersunk edge. It is highly essential that this center be kept free from grit or chips, burrs of metal, and it must be well oiled.