chucks. In general, the larger the drill (and motor), the
slower the rpm, which provides the needed extra
torque to twist a greater size drill bit.
CAUTION
Unplug the drill before attempting to
tighten or remove drill bits.
PORTABLE ELECTRIC OR
NEUMATIC OPERATED SANDER
The power sander (fig. 2-31) is one of the most
desirable tools for scaling rust, removing paint, and
smoothing decks and bulkheads before painting. The
design of the portable power sander is much like that
of the electric drill motor with the addition of the
sanding disk attached at right angles. The average size
disk sander used in the Navy is either 7 or 9 inches.
PNEUMATIC CHIPPING
HAMMER
The pneumatic chipping hammer (fig. 2-32) is
another tool useful to the ABF when scaling large
areas in preparation for repainting. Air pressure sup-
ply should be maintained to the manufacturer’s rec-
ommended working pressures found on the nameplate
attached to the tool. Never point the pneumatic chip-
ping hammer at another person or yourself while air
pressure is supplied to the tool. Personal injury could
occur if the chisel was expelled at high speed from the
scaling hammer.
ROTARY IMPACT SCALER
The rotary impact scaler (fig. 2-33) is a scaling
and chipping tool, sometimes called a jitterbug. It is
electric or pneumatic powered and has a bundle of
cutters mounted on either side. In use, it is pushed
along the surface to be scaled with the rotating chip-
pers doing the work. Replacement bundles of cutters
are available.
NEEDLE IMPACT SCALER
The needle impact scaler (fig. 2-34) has needlelike
attachments that fit into one end. It is often called a
needle-gun. This tool is used in conjunction with the
rotary scaler and can clean out (scale) corners not
reached by the other tool.
PRECISION MEASURING
EQUIPMENT
LEARNING OBJECTIVES: Identify precision
measuring equipment used by the ABF. Ex-
plain the use and care of precision measuring
equipment.
As an ABF, you will be using measuring tools that
read in the thousandths (0.001). On PMS and in major
maintenance work, you will be required to use torque
wrenches, micrometers, telescoping gages, vernier
calipers, and dial indicators. Aligning pumps, check-
ing shafts for wear, and checking bearings’ inside and
outside diameters are just a few places where these
tools are used. We will now go through the selection
and use of the proper tool for the job at hand.
TORQUE WRENCHES
There are times when, for engineering reasons, a
definite force must be applied to a nut or bolt head. In
such cases a torque wrench must be used. For example,
equal force must be applied to all the head bolts of an
engine. Otherwise, one bolt may bear the brunt of the
force of internal combustion and ultimately cause
engine failure.
The three most commonly used torque wrenches
are the deflecting beam, dial indicating, and
Figure 2-33.—Rotary impact scaler.
2-23
Figure 2-34.—Needle impact scaler (needle-gun).
