Push the saw forward at a speed which allows the blade to cut without laboring. Hardness and toughness can vary even in the same piece of material, and knotty or damp sections can put a heavy load on the saw. When this happens, push the saw more slowly, but hard enough to keep it working without much decrease in speed.
Kickback
When the saw blade becomes pinched or twisted in the cut, kickback can occur. The saw is thrust rapidly back 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 backward. When 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 more likely to occur when any of the following conditions exist.
1.IMPROPER WORKPIECE SUPPORT
A.Sagging or improper lifting of the cut off piece causing pinching of the blade (Figure 10).
B.Cutting through material supported at the outer ends only. As the material weakens it sags, closing down the kerf and pinch- ing the blade.
C.Cutting off a cantilevered or overhanging piece of material from the bottom up in a vertical direction. The falling cut off piece can pinch the blade.
D.Cutting off long narrow strips (as in ripping). The cut off strip can sag or twist closing the kerf and pinching the blade.
E.Snagging the lower guard on a surface below the material being cut momentarily reducing operator control. The saw can lift partially out of the cut increasing the chance of blade twist.
2.IMPROPER DEPTH OF CUT SETTING ON SAW
Using the saw with an excessive depth of cut setting increases loading on the unit and susceptibility to twisting of the blade in the kerf. It also increases the surface area of the blade available for pinching under conditions of kerf close down. See page 4 Cutting
Depth Adjustment.
3.BLADE TWISTING (MISALIGNMENT IN CUT)
A.Pushing harder to cut through a knot, a nail, or a hard grain area can cause the blade to twist.
B.Trying to turn the saw in the cut (trying to get back on the marked line) can cause blade twist
C.Extended reach or operating saw with poor body control (out of balance), can result in twisting the blade.
D.Changing hand grip or body position while cutting can result in blade twist.
E.Backing unit up to clear blade can lead to twist if not done care- fully.
4.MATERIALS THAT REQUIRE EXTRA ATTENTION
A.Wet lumber
B.Green lumber (material freshly cut or not kiln dried)
C.Pressure treated lumber (material treated with preservatives or
5.USE OF DULL OR DIRTY BLADES
Dull blades cause increased loading of the saw. To compensate, an operator will usually push harder which further loads the unit and promotes twisting of the blade in the kerf. Worn blades may also have insufficient body clearance which increases the chance of binding and increased loading.
6.LIFTING THE SAW WHEN MAKING BEVEL CUTS
Bevel cuts require special operator attention to proper cutting techniques - especially guidance of the saw. Both blade angle to the shoe and greater blade surface in the material increase the chance for binding and misalignment (twist) to occur.
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