| Machine Hazards > Kickbacks |
Kickbacks occur when a saw seizes the stock and hurls it back at the operator. This can happen when
the stock twists and binds against the side of the blades or is caught in the teeth. A blade that is not
sharpened, or that is set at an incorrect height, can cause kickbacks. Poor-quality lumber (in other
words, frozen lumber or lumber with many knots or foreign objects such as nails) can also result in
kickbacks. Kickbacks occur more often when cutting
parallel to the wood grain (ripping) than when cross-cutting.
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- The major hazard with kickbacks is the stock
being hurled back at the operator. Hazards due to kickbacks are most likely when there is a lack of
safeguards, such as spreaders, anti-kickback fingers, and gauge or rip fences.
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Engineering Controls
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Use a spreader to prevent material
from squeezing the saw or kicking back during
ripping.
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Use anti-kickback
fingers on both sides of the blade to hold the stock down in the event that the
saw kicks back the material.
Work Practice Controls
- Use appropriate equipment for the job.
Workers can be seriously injured if they do not
use the correct equipment for a job. Use machines
only for work within the rated capacity
specified by the machine manufacturer. Use the
correct tools on a given machine. For example,
when using a circular saw, use the correct blade
for the required cutting action. Similarly, you
must only mount blades, cutter heads, or collars
on machine arbors that have been accurately
sized and shaped to fit these parts.
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Frequently inspect equipment and guards.
Ensure that: (1) the operator and machine are
equipped with the safety accessories suitable for
the hazards of the job, (2) the machine and
safety equipment are in proper working condition,
and (3) the machine operator is properly
trained. Document the inspections and keep the
records. Documentation should identify the
machine, inspection date, problems noted, and
corrective action taken. Noting problems helps
to ensure that corrective action will be taken,
that operators on all shifts will be made aware of
any potential danger, and that any pattern of
repeat problems on a particular machine can be
detected and resolved as early as possible.
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Do not use stock that has checks, splits,
cracks, or knots.
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Allow glued joints to dry before working
on stock.
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Hold tools firmly in both hands.
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Use equipment only when guards are in place
and in working order. A worker should not be
allowed to operate a piece of woodworking
equipment if the guard or any other safety device, return device, spreader, anti-kickback
fingers apparatus, guard on in-running rolls, or
gauge or rip fence is not functioning properly.
When guards cannot be used (during rabbeting
or dadoing, for instance), you must provide combs, featherboards, or suitable jigs for
holding the stock.
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Provide regular preventive maintenance.
Regularly clean and maintain woodworking
equipment and guards. Ensure that blades are in
good condition. Knives and cutting heads must
be kept sharp, properly adjusted, and secured.
Sharpening blades prevents kickback. You must
also remove any cracked or damaged blades
from service. Keep circular saw blades round
and balanced. You must remove dull, badly set,
improperly filed or improperly tensioned saws
from service, and immediately clean saws to
which gum has adhered.
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Avoid deep cuts; they increase the likelihood of
kickbacks.
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Use appropriate personal protective equipment.
- Whenever possible, stand back or to the
side once the boards have been put
through to avoid injuries from kickback and
flying splinters.
- Do not feed boards of different thickness.
Thinner boards will be kicked back.
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