Electric disk sanders (fig. 1-61) are especially
useful on work where a large amount of material is to be
removed quickly, such as in scaling surfaces in
preparation for painting. This machine, however, must
not be used where a mirror-smooth finish is required.
The disk should be moved smoothly and lightly
over the surface. Never allow the disk to stay in one
place too long, because it will cut into the metal and
leave a large depression.
Portable grinders are power tools that are used for
rough grinding and finishing of metallic surfaces. They
are made in several sizes; however, the one used most in
the Navy uses a grinding wheel with a maximum
diameter of 6 inches. See figure 1-62.
The abrasive wheels are easily replaceable so that
different grain size and grades of abrasives can be used
for the various types of surfaces to be ground and the
different degrees of finish desired.
A flexible shaft attachment is available for most
portable grinders. This shaft is attached by removing
the grinding wheel, then attaching the shaft to the
grinding wheel drive spindle. The grinding wheel can
then be attached to the end of the flexible shaft. This
attachment is invaluable for grinding surfaces in
ELECTRIC IMPACT WRENCH
The electric impact wrench (fig. 1-63) is a portable,
hand-type reversible wrench. The one shown has a
1/2-inch-square impact-driving anvil, over which
1/2-inch-square drive sockets can be fitted. Wrenches
also can be obtained that have impact driving anvils
ranging from 3/8 inch to 1 inch. The driving anvils are
not interchangeable, however, from one wrench to
equipment is primarily intended for applying and
removing nuts, bolts, and screws. It may also be used to
drill and tap metal, wood, plastics, and so on, and to
drive and remove socket-head, Phillips-head, or
slotted-head wood, machine, or self-tapping screws.
Before you use an electric impact wrench, depress
the on-and-off trigger switch and allow the electric
wrench to operate a few seconds, noting carefully the
direction of rotation. Release the trigger switch to stop
the wrench. Turn the reversing ring, located at the rear
of the tool; it should move easily in one direction
(which is determined by the current direction of
rotation). Depress the on-and-off trigger again to start
the electric wrench. The direction of rotation should
now be reversed. Continue to operate for a few seconds
in each direction to be sure that the wrench and its
reversible features are functioning correctly. When you
Figure 1-61.Portable electric sander.
Figure 1-62.Portable grinder.
Figure 1-63.Reversible electric impact wrench.