when the blade is pinched or jammed tightly by the kerf closing down, the blade
stalls and
the motor reaction drives the unit rapidly back toward the operator;
if the blade becomes twisted or misaligned in the cut, the teeth at the back edge
of the
blade can dig into the top surface of the wood causing the blade to climb
out of the kerf
and jump back toward the operator.
Kickback is the result of saw misuse and/or incorrect operating procedures or
conditions and can be avoided by taking proper precautions as given below.
a)
Maintain a firm grip with both hands on the saw and position your arms to
resist kickback forces. Position your body to either side of the blade, but not
in line with the blade.
Kickback could cause the saw to jump backwards, but
kickback forces can be
controlled by the operator, if proper precautions are taken.
NOTE For
circular saws
with a maximum blade diameter of 140 mm or smaller, the words "with both
hands" do not apply.
b)
When blade is binding, or when interrupting a cut for any reason, release
the trigger and hold the saw motionless in the material until the blade comes
to a complete stop. Never attempt to remove the saw from the work or pull the
saw backward while the blade is in motion or kickback may occur.
Investigate
and take corrective actions to
eliminate the cause of blade binding.
c)
When restarting a saw in the workpiece, centre the saw blade in the kerf so
that the saw teeth are not engaged into the material.
If a saw blade binds, it may
walk up or
kickback from the workpiece as the saw is restarted.
d)
Support large panels to minimise the risk of blade pinching and kickback.
Large panels tend to sag under their own weight. Supports must be placed under
the panel on both sides, near the line of cut and near the edge of the panel.
e)
Do not use dull or damaged blades.
Unsharpened or improperly set blades
produce narrow kerf causing excessive friction, blade binding and kickback.
f)
Blade depth and bevel adjusting locking levers must be tight and secure
before making the cut.
If blade adjustment shifts while cutting, it may cause
binding and
kickback.
g)
Use extra caution when sawing into existing walls or other blind areas.
The
protruding blade may cut objects that can cause kickback.
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