Parting-off is the operation of cutting a work piece after it has been machined to the desired size and shape. The process involves rotating the work piece on a chuck or face plate at half the speed to that of turning and feeding by a narrow parting off tool perpendicular to the lathe axis by rotating the cross slide screw by hand. Before the operation starts, the carriage is locked in position on the lathe bed and the cutting tool is held rigidly on the tool post with the compound slide set parallel to the lathe axis. The tool should be fed very slowly to prevent chatter. The feed varies from 0.07 to 0.15 mm per revolution and the depth of cut is equal to the width of the tool. In parting off, a work of very large diameter, cuts are made in stages. The parting off tool is first fed through a certain depth, then withdrawn and two more cuts are made at the two sides of the central groove. The tool is next fed into the central groove until the work is cut off in two parts.