to force the work back. The outside
or periphery of the disk should run nearly true and it may be necessary
to move the jaws in on one side and out on the other to bring the disk
to a central position. To test its location, the lathe is run at a
moderate speed and a piece of chalk is held near the outer surface. If
the latter runs out, the "high" side will be marked by the chalk, and
this mark can be used as a guide in adjusting the jaws. It should be
remembered that the jaws are moved only one-half the amount that the
work runs out.

[Illustration: Fig. 34. (A) Radial Facing. (B) Boring Pulley Held in
Chuck]

A round-nosed tool _t_ of the shape shown can be used for radial facing
or turning operations of the kind illustrated. This tool is similar to
the form used when turning between centers, the principal difference
being in the direction of the top slope. The radial facing tool should
be ground to slope downward toward _a_ (see Fig. 35) whereas the regular
turning tool slopes toward _b_, the inclination in each case being away
from that part of the cutting edge which does the work. The cutting edge
should be the same height as the lathe centers, and the cut is taken by
feeding the tool from the outside in to the center. The cut is started
by hand and then the power feed is engaged, except for small surfaces.
The first cut should, if possible, be deep enough to get beneath the
scale, especially if turning cast iron, as a tool which just grazes the
hard outer surface will be dulled in a comparatively short time.

If it were simply necessary to turn a true flat surface and the
thickness of the disk were immaterial, two cuts would be sufficient,
unless the surface were very uneven, the first or roughing cut being
followed by a light finishing cut. For a finishing cut, the same tool
could be used, but if there were a number of disks to be faced, a
square-nosed tool _F_, Fig. 35, could probably be used to better
advantage. This type has a broad flat cutting edge that is set parallel
with the rough-turned surface and this broad edge enables a coarse feed
to be taken, thus reducing the time required for the finishing cut. If a
coarse feed were taken with the round tool, the turned surface would
have spiral grooves in it, whereas with the broad cutting edge, a smooth
surface is obtained even though the feed is coarse. The amount of feed
per revolution of the work, however, should always be less than the
width _w_ of the cu