Facing or Squaring Up. The first operation usually performed on a piece of work when placed in the lathe is facing or squaring up the ends. This must be done to get a uniform bearing for the centers. The finishing of all surfaces at or nearly at right angles to the axis of the work, is classed as facing, and the side tool,
Fig. 123, is usually employed. For roughing cuts, the cutting face of the tool is placed at a slight angle to the work surface, in order to remove the metal quickly; but for finishing cuts it is placed nearly flat against the work, so that a light, thin chip may be taken. Turning a Cylinder. Turning the cylindrical portions of the work is next done by the use of the diamond point or similar tool. Roughing cuts are taken to within about 1/64 inch of the finished size, and a fine finishing cut reduces the work to the exact diameter. For roughing cuts common calipers should be employed for test measurements; while for finishing cuts, the micrometer caliper is more suitable. All measurements must be taken with the lathe at rest, as motion of the work renders close calipering impossible.
Fig. 144. Turning a Taper by Setting over Dead Center.
It frequently happens that a piece must be turned tapering; that is, one end is to have a greater diameter than the other. There are three ways of accomplishing this result: (a) setting over the dead center, (b) the use of the compound rest, and (c) the use of the taper attachment.