process after a few passes on the O.D.
Turning constitutes the majority of lathe work. The work usually is held between centers or in a chuck,
and a right-hand turning tool is used, so that the cutting forces, resulting from feeding the tool from right
to left, tend to force the work piece against the head stock and thus provide better work support.
If good finish and accurate size are desired, one or more roughing cuts usually are followed by one or
more finish cuts. Roughing cuts may be as heavy as proper chip thickness, tool life, and lathe capacity
permit. Large depths of cuts and smaller feeds are preferred to the reverse procedure, because fewer
cuts are required and less time is lost in reversing the carriage and resetting the tool for the following
cut.
On work pieces that have a hard surface, such as castings or hot-rolled materials containing mill scale,
the initial roughing cut should be deep enough to penetrate the hard material. Otherwise, the entire
cutting edge operates in hard, abrasive material throughout the cut, and the tool will dull rapidly. If the
surface is unusually hard, the cutting speed on the first roughing cut should be reduced accordingly.
Finishing cuts are light, usually being less than .015 inch in depth, with the feed as fine as necessary to
give the desired finish. Sometimes a special finishing tool is used but often the same tool is used for
both roughing and finishing cuts, In most cases one finishing cut is all that is required.
However, where exceptional accuracy is required, two finishing cuts may be made. If the diameter is
controlled manually, it usually is desirable to make a short finishing cut of .005 and check the diameter
before completing the cut. Because the previous micrometer measurements were made on a rougher
surface, some readjustment of the tool setting may be necessary in order to have the final
measurement, made on a smoother surface, check exactly.