LEARNING OBJECTIVES: Identify the
different types of power tools. Describe the
uses of different types of power tools. List the
safety precautions that apply to power tools.
List the safety precautions that apply to
Power tools have become so commonplace in the
Navy that all ratings now use them in the performance
of maintenance at one time or another.
The following paragraphs are devoted to the
identification, general-operating practices, and care of
The portable electric drill (fig. 1-59) is probably the
most frequently used power tool in the Navy. Although
it is especially designed for drilling holes, by adding
various accessories you can adapt it for different jobs.
Sanding, sawing, buffing, polishing, screw driving,
wire brushing, and paint mixing are examples of
Portable electric drills commonly used in the Navy
have capacities for drilling holes in steel from 1/16 inch
up to 1 inch in diameter. The sizes of portable electric
drills are classified by the maximum size straight shank
drill it will hold. That is, a 1/4-inch electric drill will
hold a straight shank drill bit up to and including
1/4 inch in diameter.
The revolutions per minute (rpm) and power the
drill will deliver are most important when choosing a
drill for a job. You will find that the speed of the drill
motor decreases with an increase in size, primarily
because the larger units are designed to turn larger
cutting tools or to drill in heavy materials, and both of
these factors require slower speed.
If you are going to do heavy work, such as drilling
in masonry or steel, then you would probably need to
use a drill with a 3/8- or 1/2-inch capacity. If most of
your drilling will be forming holes in wood or small
holes in sheet metal, then a 1/4-inch drill will probably
The chuck is the clamping device into which the
drill bit is inserted. Nearly all electric drills are
equipped with a three-jaw chuck. Some drills have a
hand-type chuck that you tighten or loosen by hand, but
most of the drills used in the Navy have gear-type,
three-jaw chucks, which are tightened and loosened by
a chuck key, shown in figure 1-60. Do not apply further
pressure with pliers or wrenches after you hand tighten
the chuck with the chuck key.
Always remove the key IMMEDIATELY after you
use it. Otherwise the key will fly loose when the drill
motor is started and may cause serious injury to you or
one of your shipmates. The chuck key is generally
taped on the cord of the drill; but if it is not, make sure
you put it in a safe place where it will not get lost.
All portable electric drills used in the Navy have
controls similar to the ones shown on the 1/4-inch drill
in figure 1-59. This drill has a momentary contact
trigger switch located in the handle. The switch is
squeezed to start the electric drill and released to stop it.
The trigger latch is a button in the bottom of the
drill handle. It is pushed in while the switch trigger is
held down to lock the trigger switch in the ON position.
The trigger latch is released by squeezing and then
releasing the switch trigger.
Figure 1-59.1/4-inch portable electric drill.
Figure 1-60.Three-jaw chuck and chuck key.