kerf. Put an adjustable wrench across this new flat and
the one opposite, and again try to remove the frozen
nut. Since very little original metal remains on this one
side of the nut, the nut will either give or break away
entirely and permit its removal.
To saw a wide kerf in the head of a cap screw or
machine bolt, fit the hand hacksaw frame with two
blades side by side, and with teeth lined up in the same
direction. With slow, steady strokes, saw the slot
approximately one-third the thickness of the head of the
cap screw, as shown in figure 1-18. Such a slot will
permit
subsequent
holding
or
turning
with
a
screwdriver when it is impossible, due to close quarters,
to use a wrench.
Hacksaw Safety
The main danger in using hacksaws is injury to
your hand if the blade breaks. The blade will break if
too much pressure is applied, when the saw is twisted,
when the cutting speed is too fast, or when the blade
becomes loose in the frame. Additionally, if the work is
not tight in the vise, it will sometimes slip, twisting the
blade enough to break it.
CHISELS
Chisels are tools that can be used for chipping or
cutting metal. They are made from a good grade of tool
steel and have a hardened cutting edge and beveled
head. Chisels are classified according to the shape of
their points, and the width of the cutting edge denotes
their size. The most common shapes of chisels are the
flat (cold chisel), cape, round nose, and diamond point
(fig. 1-19).
The type of chisel most commonly used is the flat
cold chisel, which serves to cut rivets, split nuts, chip
castings, and cut 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. Finally, the
diamond-point is used for cutting V-grooves and sharp
corners.
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.
When using a chisel for chipping, always wear
goggles to protect your eyes. If others are working close
by, see that 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
There are a number of different types of files in
common use, and each type may range in length from
3 to 18 inches.
1-13
Figure 1-18.—Cutting a wide kerf in the head of a cap screw or
bolt.
Figure 1-19.—Types of points on metal-cutting chisels.
