vertically. The work table is firmly gibbed to vertical
ways or tracks on the front of the column and is
further supported by a heavy adjusting screw from the
base to the bottom of the table. As the table can be
moved only vertically, it is necessary to position the
work for each hole.
Sensitive Drill Press
The sensitive drill press (fig. 4-26) is used to drill
small holes in work under conditions that make it
necessary for the operator to "feel" what the cutting
tool is doing. The tool is fed into the work by a very
simple device-a lever, a pinion and shaft, and a rack
that engages the pinion. These drills are nearly
always belt-driven because the vibration caused by
gearing would be undesirable. Sensitive drill presses
are used to drill holes less than one-half inch in
diameter. The high-speed range of these machines
and the holding devices used make them unsuitable
for heavy work.
RADIAL DRILL PRESS
The radial drill press shown in figure 4-27, has a
spindle head on an arm that can be rotated axially on
Figure 4-26.--Sensitive drill press.
Figure 4-27.--Radial drill press.
4-16