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Aviation Boatswains Mate E 3 & 2 - Aviation theories and other practices | Next
HACKSAWS |
Figure 1-18.-Metal snips.
cutting heavy material, use the rear portion of the
blades. This procedure not only avoids the possibility
of springing the blades but also gives you greater
cutting leverage.
Many snips have small serrations (notches) on the
cutting edges of the blades. These serrations tend to
prevent the snips from slipping backwards when a cut
is being made. Although this feature does make the
actual cutting easier, it mars the edges of the metal
slightly. You can remove these small cutting marks
if you allow proper clearance for dressing the metal to
size. There are many other types of hand snips used
for special jobs, but the snips discussed here can be
used for almost any common type of work.
Cutting Sheet Metal with Snips
It is hard to cut circles or small arcs with straight
snips. There are snips especially designed for circular
cutting. They are
called CIRCLE SNIPS,
HAWKS-BILL SNIPS, TROJAN SNIPS, and
AVIATION SNIPS (fig. 1-18).
To cut large holes in the lighter gauges of sheet
metal, start the cut by punching or otherwise making
a hole in the center of the area to be cut out. With an
aviation snips, or some other narrow-bladed snips,
make a spiral cut from the starting hole out toward the
scribed circle, as shown in figure 1-19, and continue
cutting until the scrap falls away.
Figure 1-19.-Cutting an inside hole with snips.
To cut a disk in the lighter gauges of sheet metal,
use a combination snips or a straight-blade snips, as
shown in figure 1-20.
First, cut away any surplus
material outside the scribed circle, leaving only a
narrow piece to be removed by the final cut. Make
the final cut just outside the layout line. This will
permit you to see the scribed line while you are
cutting and will cause the scrap to curl up below the
blade of the snips, where it will be out of the way
while the complete cut is being made.
To make straight cuts, place the sheet metal on a
bench with the marked guideline over the edge of the
bench and hold the sheet down with one hand. With
the other hand, hold the snips so that the flat sides of
the blades are at right angles to the surface of the
Figure 1-20.-Cutting a disk out of sheet metal.
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