The work is made to rotate on the lathe centers by fastening a lathe
dog to the shaft at the head-stock end, as shown at A in Fig. 5.
[Illustration: Fig. 5]
The tail-stock center is adjusted so that the shaft will rotate freely,
yet be tight enough to allow no slack, or lost motion. Since the shaft
rotates on this center, it should be kept well lubricated by using
machine oil, or a mixture of graphite and oil.
To get the best results in turning this sort of work, it is necessary
to face both ends before turning and to rough turn the whole piece to
within about 0.03, or 0.04 of an inch of the finished size before any
part of it is finished. However, it is not always necessary to do this.
The object of first rough turning the shaft all over is to remove the
internal strains of the steel and to wear the centers down to a good
bearing before any finishing cuts are taken. The purpose of facing the
ends is to get them square, or true, and smooth.