i. 10-inch adjustable jaw wrench
increase the amount to be torn out and will increase the
j. Additional tools for the power unit
power accordingly.
12-5. A rip chisel tooth saw cuts across the center and
tears out the two corners. For this reason, the width of
12. Caring for the Saw
the cut or stroke does not materially affect the power
required The two edges have to be torn free, regardless
12-1. Your job is not complete when you finish
of how narrow the cut or stroke is, and this is what
sawing the lumber. You must take care of the saw. It is
consumes the power. Notice the chisel tooth shown in
impossible to place enough emphasis on taking care of
figure 51. The corners of the tooth do the tearing.
the saw. It can truthfully be said that it is the most
Therefore, the things that lessen the tearing effect of the
important part of any type of machine which converts
corners will affect the power consumption immediately
logs into lumber, whether it be a stationary or a portable
and cause a corresponding increase in the power used
sawmill. If you do not take care of your saw, it can slash
through each tooth. This can cause much trouble.
your production, ruin the accuracy of the dimensions if
Therefore, the condition of the corners of the teeth is of
the lumber, and leave you in the depths of despair.
great importance.
12-2. There is nothing on the sawmill that takes as
12-6. In addition, if one corner of the tooth becomes
much abuse as the saw. For instance, should a log come
duller than the other, the one causing the greater
loose from the dogs while this tremendous strain is on
resistance will have a tendency to force the saw the
the saw, it will very likely kink (bend) it, bringing a halt
opposite way, which will cause the side of the saw to rub
to operations and resulting in loss of time and manpower.
on the side of the log. If the saw rubs on the side of the
All saws vary considerably and require different methods
log, it will do one of two things: (1) If the log is moving
of handling. This is partly due to the hardness or
endways slowly, and if the saw is rotating as it rubs the
mildness (softness) of the steel from which they are
slowly moving log, it will generate heat in the saw which
made.
will cause the metal to expand. This, in turn, will cause
12-3. Teeth. A new saw will always run well for a
the saw to lose the stiffness required to run straight The
few hours. It may make a rather rough cut, but it will
further this condition is allowed to develop, the more
always run a few hours if the saw is tensioned for the
difficult it becomes to remedy. (2) On the other hand, if
proper speed and the natural lead is properly set. These
the log is passing the saw at a higher rate of speed, the
facts assure you that, if the teeth can be kept properly
saw will have a tendency to cool as it rubs against the
sharpened (like new teeth), the saw will continue to run
log, because the inside of the
and cut in a true line. Therefore, when you find that it
does not do this, the deviation usually indicates that the
saw teeth have not been sharpened properly. It has been
proven that if an improperly sharpened saw is too long it
will lose the proper tension and may cause blisters to
develop on the saw blade. If this happens, you will have
to have a competent saw expert retension the saw by
hammering it. Hammering a saw is an art and should
under no circumstances be attempted by anyone with
limited experience. When your saw ceases to cut
properly, stop your operations and sharpen it.
12-4. Blade. Most of your sawing will be done with a
chisel tooth. So let's find out how a chisel tooth saw
works. Many saws used to cut wood lengthwise of the
grain are swedge-set chisel tooth saws. Many saws used
to cut crosswise of the grain are spring-set pointed tooth
saws. A spring-set cutoff saw cuts the sides free and
tears out the portion between the two edges that are cut
free by the sharp points. Therefore, as soon as the point
become dull and do not cut the edges free, further
sawing is difficult, and the saw is said to be dull.
Sharpening the points will correct this situation and you
can resume your work. Inasmuch as the center is torn
out, any alight increase in the kerf (cut or stroke) will
Figure 51. Chisel tooth.
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