Tc 9-524 fundamentals of machine tools

Depth of Cut
Depth of cut is the distance that the tool bit moves into the
work. usually measured in thousandths of an inch or in
millimeters. General machine practice is to use a depth of cut
up to five times the rate of feed, such as rough cutting
stainless steel using a feed of 0.020 inch per revolution and a
depth of cut of 0.100 inch. which would reduce the diameter
by 0.200 inch. If chatter marks or machine noise develops.
reduce the depth of cut.
MICROMETER COLLAR
Graduated micrometer collars can be used to accurately
measure this tool bit movement to and away from the lathe
center axis. Thus. the depth of cut can be accurately measured
when moving the tool bit on the cross slide by using the cross
slide micrometer collar. The compound rest is also equipped
with a micrometer collar. These collars can measure in inches
or in millimeters, or they can be equipped with a dual readout
collar that has both. Some collars measure the exact tool bit
movement. while others are designed to measure the amount
of material removed from the workpiece (twice the tool bit
movement). Consult the operator’s instruction manual for
specific information on graduated collar use.
FACING
Facing is machining the ends and shoulders of a piece of
stock smooth. flat, and perpendicular to the lathe axis. Facing
is used to cut work to the desired length and to produce a
surface from which accurate measurements may be taken.
Facing Work in a Chuck
Facing is usually performed with the work held in a chuck
or collet. Allow the workpicce to extend a distance no more
than 1 1/2 times the work diameter from the chuck jaws. and
use finishing speeds and feeds calculated using the largest
diameter of the workpiece. The tool bit may be fed from the
outer edge to the center or from the center to the outer edge.
Normal facing is done from the outer edge to the center since
this method permits the operator to observe the tool bit and
layout line while starting the cut. This method also eliminates
the problem of feeding the tool bit into the solid center
portion of the workpiece to get a cut started.. Use a left-hand
finishing tool bit and a right-hand tool holder when facing
from the outer edge toward the center. Work that has a drilled
or bored hole in the center may be faced from the center out