The type of chisel most commonly used is the flat
cold chisel, which serves to cut rivets, split nuts, chip
castings, and thin metal sheets. The cape chisel is
used for special jobs like cutting keyways, narrow
grooves, and square corners. Round-nose chisels
make circular grooves and chip inside corners with a
fillet. Finally, the diamond-point is used for cutting
V-grooves and sharp comers.
As with other tools there is a correct technique
for using a chisel. Select a chisel that is large enough
for the job. Be sure to use a hammer that matches the
chisel; that is, the larger the chisel, the heavier the
hammer. A heavy chisel will absorb the blows of a
light hammer and will do virtually no cutting.
As a general rule, hold the chisel in the left hand
with the thumb and first finger about 1-inch from the
top. It should be held steadily but not tightly. The
finger muscles should be relaxed, so if the hammer
strikes the hand it will permit the hand to slide down
the tool and lessen the effect of the blow. Keep the
eyes on the cutting edge of the chisel, not on the
head, and swing the hammer in the same plane as
the body of the chisel. If you have a lot of chiseling to
do, slide a piece of rubber hose over the chisel. This
will lessen the shock to your hand.
When using a chisel for chipping, always wear
goggles to protect your eyes. If other personnel are
working close by, ensure they are protected from
flying chips by erecting a screen or shield to contain
the chips. Remember that the time to take these
precautions is before you start the job.
FILES
A toolkit for nearly every rating in the Navy is
not complete unless it contains an assortment of files.
There are several different types of files in common
use, and each type may range in length from 3 to 18
inches.
Grades
Files are graded according to the degree of
fineness and according to whether they have single or
double-cut teeth. The difference is apparent when you
compare the files in figure 2-8, view A.
Single-cut files have rows of teeth cut parallel to each
other. These teeth are set at an angle of about 65
degrees with the center line. You will use single-cut
files for sharpening tools, finish filing, and
drawfiling. They also are the best tools for smoothing
the edges of sheet metal.
Files with crisscrossed rows of teeth are double-
cut files. The double cut forms teeth that are
diamond-shaped and fast cutting. You
will use
double-cut files for quick removal of metal and for
rough work.
Figure 2-8.—File descriptions.
2-6
