Makita 5143R, 5903R, 5703R, 5103R Causes and Operator Prevention of Kickback, Fig. B

9.Causes and Operator Prevention of Kickback:

–kickback is a sudden reaction to a pinched, bound or misaligned saw blade, causing an uncontrolled saw to lift up and out of the workpiece toward the operator;

–when the blade is pinched or bound 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.

•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 kick- back forces can be controlled by the operator, if proper precautions are taken.

•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 correc- tive actions to eliminate the cause of blade bind- ing.

•When restarting a saw in the workpiece, centre the saw blade in the kerf and check that saw teeth are not engaged into the material. If saw blade is binding, it may walk up or kickback from the workpiece as the saw is restarted.

•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.

•To minimize the risk of blade pinching and kick- back. When cutting operation requires the resting of the saw on the workpiece, the saw should be rested on the larger portion and the smaller piece cut off. (Fig. B & C)

To avoid kickback, do support board or panel near the cut.

Fig. B

Don’t support board or panel away from the cut.

Fig. C

•Do not use dull or damaged blades. Unsharp- ened or improperly set blades produce narrow kerf causing excessive friction, blade binding and kick- back. Keep blade sharp and clean. Gum and wood pitch hardened on blades slows saw and increases potential for kickback. Keep blade clean by first removing it from tool, then cleaning it with gum and pitch remover, hot water or kerosene. Never use gasoline.

•Blade depth and bevel adjusting locking levers must be tight and secure before making cut. If blade adjustment shifts while cutting, it may cause binding and kickback.

•Use extra caution when making a “plunge cut” into existing walls or other blind areas. The protruding blade may cut objects that can cause kickback. For plunge cuts, retract lower guard using retracting handle.

•ALWAYS hold the tool firmly with both hands. NEVER place your hand or fingers behind the saw. If kickback occurs, the saw could easily jump backwards over your hand, leading to serious per- sonal injury. (Fig. D)

Fig. D

•Never force the saw. Forcing the saw can cause uneven cuts, loss of accuracy, and pos- sible kickback. Push the saw forward at a speed so that the blade cuts without slowing.

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