Figure 1-64.-Portable electric sander.
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
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 1-65.
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
hard-to-reach places.
ELECTRIC IMPACT WRENCH
The electric impact wrench (fig. 1-66) 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 another.
The electric wrench with its accompanying
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
Figure 1-65.-Portable grinder.
Figure 1-66.-Reversible electric impact wrench.
1-38
