Figure 4-97. Hacksaw Blade Set
Stock thickness. Heavy stock is usually
cut with the all-hard blade because it has less tendency
to wander. The flexible blade is less likely to break and
is used for thin stock.
Stock hardness. Generally speaking, the
pitch of the blade depends on the hardness of the stock.
Figure 4-98 shows the typical applications for the
different saw blade pitches.
When cutting any stock, there should
always be at least two teeth working on
the stock. Therefore, for thin-walled
stock, a finer blade than that ordinarily
used may be necessary.
Figure 4-98. Application of Blade Pitch for
Use. The following paragraphs provide
general procedures for the use of hacksaws:
Install the blade in the hacksaw frame as
shown in figure 4-99. Ensure that the teeth point away
from the handle. Tighten the wing nut so that the blade
is under tension.
Figure 4-99. Installing a Hacksaw Blade
Place the stock to be cut in a vise.
Maintain a minimum of overhang to reduce vibration,
give a better cut, and lengthen the life of the blade.
Ensure that the layout line on the stock is outside of the
vise jaw so that the line is visible during sawing.
Hold the hacksaw as shown in figure 4-
When cutting, apply pressure on the
forward stroke, which is the cutting stroke. Do not apply
pressure on the return stroke. Use long and smooth
strokes. Do not exceed 60 strokes per minute.
4-18. Taps and Dies. Taps and dies are made of hard,
tempered steel, and are used to cut threads in metal,
fiber, or plastic. Four types of threads may be cut with
standard taps and dies. These are national coarse,
national fine, national extra fine, and national pipe. The
following paragraphs describe the types and uses of
taps, dies, and accessories.