192 Agricultural Mechanics and Technology Systems
Copyright Goodheart-Willcox Co., Inc.
between the shank and the tapered socket.
The spindle of many drill presses is
designed with a Morse taper to accept the
chuck assembly or a Morse taper drill bit.
The drilling, or rotating, speed of a
drill press is adjusted by changing the
arrangement of a belt or combination of
belts within the drive motor housing. The
belts are positioned between stacks of pulleys
of different sizes attached to the drive motor
and the spindle. Moving the belts changes
the drive ratio, thus changing the speed
and torque delivered at the drill bit. The
physical properties of the work material
and the size of the drill bit determine the
optimum speed for drilling. See Figure 8-16.
A common drill press accessory is the
drill press vise. These vises are machined
fl at on the base to be clamped securely to
the drill press table. The parallel sides of
the vise are capable of holding fl at or round
objects. Using a drill press vise is the safest
and most stable method to hold materials
while drilling.
Drilling Tool Rules
When operating a drilling tool, follow
all the power tool safety rules outlined
earlier, along with these specifi c rules:
• Tighten, if necessary, a Jacobs chuck using all three holes. Remove the
chuck key before drilling.
Drive motor
Depth
adjustment
Column
Table
adjustment
Table
Chuck
Hand-feed
lever
Power switch
Belt guard
Goodheart-Willcox Publisher
Figure 8-15. Using a drill press instead of a handheld power
drill provides added precision for the location and placement
of drilled holes.
B
Goodheart-Willcox Publisher
Figure 8-16. A—Most drill presses operate at variable speeds to accommodate the
characteristics of different raw materials. Note the numerous possible belt configurations
on the pulleys of this drive motor. B—Refer to the drill speed chart located either directly
on the drill press or in the operator’s manual to set the drilling speed prior to drilling. The
chart on the right displays belt positions for the different speeds.
A
Goodheart-Willcox Publisher