Protecting yourself from kickback:
• Keep your left arm as straight as possible.
• Keep your left hand behind the guard/chain brake.
• Keep your left thumb wrapped opposite your fingers.
• Do not stand directly in line with the guide bar but slightly to the left.
• Wear your personal protective equipment.
Pull-In
If you are cutting on the bottom of the guide bar (the section of chain that is returning to the saw head), the force tends to pull the saw and the operator in toward the wood, or vise-versa This is called pull-in and can happen quickly. The operator may be pulled off balance, the wood might be thrown back at the operator, or the saw may be pulled forward, inadvertantly contacting something, causing kickback.
When cutting with the bottom of the bar on the top of a log, the natural reactive force tends to pull the saw in toward the wood.
Pull-in occurs when cutting on the bottom, far end of the bar. It can happen quickly enough to pull the operator off balance, losing control of the saw.
To prevent pull-in, work with the saw head close to the wood you are cutting.
Work with the saw head (not the tip) close to the wood. Always cut at full throttle and push down slowly enough to keep the engine and chain speed high. This cuts the wood rather than “biting” it.
Push-Back
Push-back happens when you are cutting from below, using the chain on the top of the guide bar. This chain is moving away from the saw head. You often need to do this when cutting limbs from a tree (here). The force of the moving chain pushes the saw and the operator away from the wood you are cutting. The problem is that if the force pushes the guide bar completely out of the wood, the chainsaw can kick back into the operator. As the bar leaves the cut, if the upper quadrant of the bar nose contacts the wood, the push-back will turn into a kickback.
When cutting on the underside of a log (with the top of the bar), the saw wants to quickly push away from the wood.
Push-back occurs when cutting on the top of the bar. If not controlled, the bar nose can contact the wood, leading to kickback.
■ Always cut at full throttle and ease into the cut so the chain is less likely to catch the wood.
■ Do not cut with the upper end (nose) of the bar.
■ Keep your left hand thumb wrapped tightly around the top handle and behind the front guard/chain brake, in position to activate the brake automatically. See top photo (here).
■ Position your body to the left of the line of cut. See here. Then, if there is a kickback, the bar and chain will pass to the right of you.
Wrapping your left thumb around the top handle ensures a firm grip and greater control, and allows the chain brake to operate in the event of kickback.
Stand firmly with legs slightly separated and to the left of the cut line.
Pinch
Pinch can be one of the most frustrating problems when cutting with a chainsaw. It happens when the saw’s guide bar and chain literally get pinched in the wood (right). A pinched chain can also push back and kick back.
When trying to remove a pinched guide bar, do not use a second chainsaw to “cut out” the first one. The second saw can get pinched or damaged when it hits the first saw. Also, do not try to pull, twist, or force the saw out as this could cause damage to the bar and chain. There is a “correct” way to free a pinched saw using a second saw—see here.
How does pinch happen? Often it is when cutting down on a section of log that is supported on both ends (below). A log that is supported this way is under a lot of compression stress on the top side and tension stress on the bottom side. As you cut down from the top, the center of the log will drop before it is cut completely through. This closes up the kerf and pinches the bar and chain.
This log is supported by brush on both ends and a prime candidate for pinching the guide bar.
The guide bar is pinched halfway through the cut. Tugging on the saw to free the bar has pulled the chain out of the bar slot.
Making angled bucking cuts
When a section of trunk is balanced in such a way that one cut section is likely to remain stationary while the other falls toward the guide bar, make the two bucking cuts at an angle to prevent pinch.
Make the first cut from the top, angling it downward toward the section of the tree that will remain stationary. Saw one-third of the way through the trunk. To sever the pieces, cut up from underneath at about the same angle.
When cutting down into a log supported on both ends, the kerf closes up and pinches the bar in place.
The best solution is to lift the branch or log to relieve the pinch and then remove the saw. Shut the saw off, then use a second tree branch or sturdy sapling as a lever to lift the log and relieve the tension, as shown at left.
Next, carefully lift out the pinched saw, left.
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