MILLING MACHINE OPERATIONS - OD1644 - LESSON 1/TASK 1
For safety reasons, extreme caution should be exercised while
using the rapid traverse controls.
The table is the rectangular casting located on top of the
saddle. It contains several T-slots for fastening the work or workholding
devices. The table can be moved by hand or by power. To move the table by
hand, engage and turn the longitudinal hand crank.
To move it by power,
engage the longitudinal directional feed control lever.
directional control lever can be positioned to the left, to the right, or in
the center. Place the end of the directional feed control lever to the left
to feed the table to the left. Place it to the right to feed the table to
the right. Place it in the center position to disengage the power feed, or
to feed the table by hand.
Spindle. The spindle holds and drives the various cutting tools. It
is a shaft, mounted on bearings supported by the column.
The spindle is
driven by an electric motor through a train of gears, all mounted within the
The front end of the spindle, which is near the table, has an
internal taper machined on it. The internal taper (3 1/2 inches per foot)
permits mounting tapered-shank cutter holders and cutter arbors. Two keys,
located on the face of the spindle, provide a positive drive for the cutter
holder, or arbor.
The holder or arbor is secured in the spindle by a
drawbolt and jamnut, as shown in figure 3 on the following page. Large face
mills are sometimes mounted directly to the spindle nose.
The overarm is the horizontal beam to which the arbor
support is fastened. The overarm, may be a single casting that slides in
the dovetail ways on the top of the column. It may consist of one or two
cylindrical bars that slide through the holes in the column.
machines to position the overarm, first unclamp the locknuts and then extend
the overarm by turning a crank. On others, the overarm is moved by merely
pushing on it.
The overarm should only be extended far enough to so
position the arbor support as to make the setup as rigid as possible. To
place the arbor supports on an overarm, extend one of the bars approximately
1-inch farther than the other bar.