work is completely cut through. Block up irregular
The speed of hacksaws is stated in strokes per
shapes so that the vise holds firmly. Check the blade
minute, counting only those strokes on which the
to be sure it is sharp and that it is secured at the proper
blade comes in contact with the stock. You will use a
tension.
gear lever to change speeds. There may be a chart
attached to or near the saw, giving recommended
Place the workpiece in the clamping device,
speeds for cutting various metals. You may use the
adjusting it so the cutting off mark is in line with the
following speeds:
blade. Turn the vise lever to clamp the material in
place. Be sure the material is held firmly.
Medium and low carbon steel, brass, and soft
metals--136.
See that the blade is not touching the workpiece
when you start the machine. You often break blades
Alloy steel, annealed tool steel, and cast
when you don't follow this rule. Feed the blade
iron--90.
slowly into the work, and adjust the coolant nozzle so
that it directs the fluid over the saw blade.
Unannealed tool steel, and stainless steel--60.
CONTINUOUS FEED CUTOFF SAW
Saw Operation
Figure 4-3 illustrates a type of cutoff saw that is
A power hacksaw is relatively simple to operate.
now being used in most shops throughout the Navy.
There are, however, a few checks you should make to
There are different models of this saw, but the basic
ensure good cuts. Support overhanging ends of long
design and operating principles remain the same.
pieces to prevent sudden breaks at the cut before the
Figure 4-3.--Continuous feed cutoff saw.
4-3
