Tc 9-524 fundamentals of machine tools

Setting Depth of Cut
In straight turning, the cross feed or compound rest
graduated collars are used to determine the depth of cut,
which will remove a desired amount from the workpiece
diameter. When using the graduated collars for measurement,
make all readings when rotating the handles in the forward
direction. The lost motion in the gears, called backlash,
prevents taking accurate readings when the feed is reversed. If
the feed screw must be reversed, such as to restart a cut, then
the backlash must be taken up by turning the feed screw
handle in the opposite direction until the movement of the
screw actuates the movement of the cross slide or compound
rest. Then turn the feed screw handle in the original or desired
direction back to the required setting. 
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Setting Tool Bit for Straight Turning
See Figure 7-49. For most straight turning operations, the
compound rest should be aligned at an angle perpendicular to
the cross slide, and then swung 30° to the right and clamped in
position. The tool post should be set on the left-hand side of
the compound rest T-slot, with a minimum of tool bit and tool
holder overhang.
When the compound rest and tool post are in these positions,
the danger of running the cutting tool into the chuck or
damaging the cross slide are minimized. Position the roughing
tool bit about 5° above center height for the best cutting
action. This is approximately 3/64-inch above center for each
inch of the workpiece diameter. The finishing tool bit should
be positioned at center height since there is less torque during
finishing. The position of the tool bit to the work should be set
so that if anything occurs during the cutting process to change
the tool bit alignment, the tool bit will not dig into the work,
but instead will move away from the work. Also, by setting
the tool bit in this position, chatter will be reduced. Use a
right-hand turning tool bit with a slight round radius on the
nose for straight turning. Always feed the tool bit toward the
headstock unless turning up to an inside shoulder. Different
workplaces can be mounted in a chuck, in a collet, or between
centers. Which work holding device to use will depend on the
size of the work and the particular operation that needs to be
performed.