KNEE: The knee is the casting that supports the
position this lever to the left, to the right, or in the
table and the saddle. The feed change gearing is
center. Place the end of the lever to the left to feed the
enclosed within the knee. It is supported and is
table toward the left. Place it to the right to feed the
adjusted by turning the elevating screw. The knee is
table toward the right. Place it in the center to
fastened to the column by dovetail ways. You can
disengage the power feed or to feed the table by hand.
raise or lower the knee by either hand or power feed.
SPINDLE: The spindle holds and drives the
You usually use hand feed to take the depth of cut or
various cutting tools. It is a shaft mounted on bearings
to position the work and power feed to move the work
during the operation.
supported by the column. The spindle is driven by an
electric motor through a train of gears, all mounted
SADDLE and SWIVEL TABLE: The saddle
within the column. The front end of the spindle,
slides on a horizontal dovetail (which is parallel to the
which is near the table, has an internal taper machined
axis of the spindle) on the knee. The swivel table (on
in it. The internal taper (3 1/2 inches per foot) permits
universal machines only) is attached to the saddle and
you to mount tapered-shank cutter holders and cutter
can be swiveled approximately 45° in either direction.
arbors. Two keys, located on the face of the spindle,
provide a positive drive for the cutter holder, or arbor.
POWER FEED MECHANISM: The power feed
You secure the holder, or arbor, in the spindle by a
mechanism is contained in the knee and controls the
longitudinal, transverse (in and out), and vertical
face mills are sometimes mounted directly to the
feeds. To set the rate of feed on machines, like the
one in figure 7-5, position the feed selection levers as
indicated on the feed selection plate. On machines
OVERARM: The overarm is the horizontal beam
handle until the desired rate of feed is indicated on the
to which you fasten the arbor support. The overarm
feed dial. Most milling machines have a rapid
may be a single casting that slides in dovetail ways on
traverse lever that you can engage when you want to
the top of the column (fig. 7-5) or it may consist of
temporarily increase the speed of the longitudinal,
one or two cylindrical bars that slide through holes in
transverse, or vertical feeds. For example, you would
engage this lever to position or align the work.
overarm on some machines, first unclamp locknuts
and then extend the overarm by turning a crank. On
NOTE: For safety reasons, you must use extreme
others, move the overarm by simply pushing on it.
caution whenever you use the rapid traverse controls.
You should extend the overarm only far enough to
TABLE: The table is the rectangular casting
position the arbor support to make the setup as rigid as
located on top of the saddle. It contains several T-slots
possible. To place arbor supports on an overarm such
in which you can fasten work or workholding devices.
You can move the table by hand or by power. To
bars approximately 1 inch farther than the other bar.
move it by hand, engage and turn the longitudinal
Tighten the locknuts after you position the overarm.
handcrank. To move it by power, engage the
On some milling machines the coolant supply nozzle
longitudinal directional feed control lever. You can
is fastened to the overarm. You can mount the nozzle
Figure 7-7.--Spindle drawbolt.