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Aviation Boatswains Mate E 3 & 2 - Aviation theories and other practices | Next
Chisels |
left, and so on. On the raker set blade, every third
tooth remains straight and the other two are set
alternately. On the wave (undulated) set blade, short
sections of teeth are bent in opposite directions.
Using Hacksaws
The hacksaw is often used improperly. Although
it can be used with limited success by an
inexperienced person, a little thought and study given
to its proper use will result in faster and better work
and in less dulling and breaking of blades.
Good work with a hacksaw depends not only upon
the proper use of the saw but also upon the proper
selection of the blades for the work to be done.
Figure 1-23 will help you select the proper blade to
use when sawing metal with a hacksaw.
Coarse
blades, with fewer teeth per inch, cut faster and are
less likely to choke up with chips. However, finer
blades, with more teeth per inch, are necessary when
thin sections are being
made so that, as each
ahead of it will still be
To make the cut,
cut. The selection should be
tooth starts its cut, the tooth
cutting.
first install the blade in the
hacksaw frame (fig. 1-24) so the teeth point away
from the handle of the hacksaw. (Hand hacksaws cut
on the push stroke.) Tighten the wingnut until the
blade is definitely under tension. This helps make
straight cuts.
Figure 1-24.-Installing a hacksaw blade.
Place the material to be cut in a vise. A
minimum of overhang will reduce vibration, give a
better cut, and lengthen the life of the blade. Have
the layout line outside of the vise jaw so that the line
is visible while you work.
The proper method of holding the hacksaw is
depicted in figure 1-25. See how the index finger of
the right hand, pointed forward, aids in guiding the
frame.
When cutting, let your body sway ahead and back
with each stroke.
Apply pressure on the forward
stroke, which is the stroke, but not on the return
stroke. From 40 to 50 cutting strokes per minute is
the usual speed.
Long, slow, steady strokes are
preferred.
Figure 1-23.-Selecting the proper hacksaw blade.
1-15
Figure 1-25.-Proper way to hold a hacksaw.
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