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Never felt a kickback - what happens?

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by wahoowad, Mar 13, 2006.

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  1. wahoowad

    wahoowad Minister of Fire

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    I have never felt a kickback, although I hold my chainsaw firmly in anticipation to control what I think it will feel like. Can someone describe the force? I imagine it feels like the tip is being rotated back towards me, counter-clockwise, just very strongly?

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  2. Eric Johnson

    Eric Johnson Mod Emeritus

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    If you have a modern saw, you might not feel it at all. If your inertial chain brake is triggered unexpectedly while cutting, then kickback probably caused it. I've never had an out-of-control kickback, even when using big saws with no chain brakes, but plenty of smaller ones that get your attention. It's just a hard shock that, if hard enough, can make your right hand go numb. Always keep your thumbs wrapped around the handles and you shouldn't have a problem with modern saws and safety chain.

    BTW, the biggest hazard in woods work, other than the obvious things that come from above, is the danger of falling. Always take your time when you work and pay attention to where your feet are. Ain't none of us getting any younger, and the bones become more brittle with age, I'm told.
  3. Corey

    Corey Minister of Fire

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    Never had anything while cutting straight through wood in the normal manner. My 350 also has the vibration isolated handle so I don't really get a lot of vibration out of the motor or off the chain through the handle. But once while cutting through a tree like Eric shows in his avatar, the tip of the chain hit a small bit of uncut wood and shot the saw out to the side. Wasn't hard enough to set off the inertial brake, though.

    My understanding is that kickback mainly ocurrs when the tip of the saw contacts a log at a location slightly below the centerline of the log. The tip starts to cut into the wood but is also forcing the saw up and since you are under the centerline, up is also forcing the saw deeper into the wood. This leads the tip of the saw to flip back out of the cut, toward the sawyer.

    Maybe the more experienced cutters can say if it happens on straight, level cuts, too...maybe that is more rare but can still happen. Generally, I try to be extra careful of where the tip of the blade is, especially when limbing the tree.

    Corey

    Here are a couple pages out of the Husky manual describing the process in more detail

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  4. Corey

    Corey Minister of Fire

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    next page

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  5. Eric Johnson

    Eric Johnson Mod Emeritus

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    You've pretty much got it covered, Corey. Thanks for scanning and posting the brochure--that's all good information.

    The tip of your bar is what you need to keep an eye on. That's another reason for not having a longer bar than you need. For my money, the most dangerous place to contact a log, from a kickback point of view, is at the end of the log. Regular chain saw chains are not designed to rip-cut wood; they're cross-cutting tools. If you hit the end of the log with the tip of the saw while the chain is turning, it will jam. And when it jams, all that force has to go somewhere, usually forcing the tip of the bar up and back towards you.

    A major cause of kickback is when you've filed your rakers too low. A brand new chain right out of the box probably wouldn't kick unless you went out of your way to make it happen. That's why guys like the one in my avatar can get away with bore-cutting, which is basically just revving up the saw and poking it into the wood with the tip. I don't recommend that anyone try bore cutting without some training or experience, but it's a legitimate method for professional cutters, and very useful in directional felling--if you know what you're doing.
  6. elkimmeg

    elkimmeg Guest

    Eric about notching: I think when it is obvious where the tree is leaning, one needs to cut the first cut about 1/4 to 1/3 in the direction of the fall. Then make your next cut about 6" above the prior cut.( from the opposite side) Not an an angle but straight threw. Probably about half way threw the tree should start falling the remaining center piece un cut acts as a hinge. It this time your saw should be turned off and you are retreating in the opposite direction of the fall path. That hinge also helps prevent the tree from kicking back. At this point you should be clear away from danger. Remember not all things go according to plan. Stay out of harm's way till the tree reaches the ground.
    Even with a hinge that tree can kick twist turn and do things unpredictable. If it does you are safely away from harm. Never stay near the trunk with the saw running watching it fall Especially if larger than 8 " One branch can hang up and things happen real quickly
  7. Eric Johnson

    Eric Johnson Mod Emeritus

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    Felling theory on this side of the Atlantic began to change in the mid '80s when superior Swedish chain saw techniques began to be implemented, largely thanks to aggressive training programs designed to cut down on the number of logging-related injuries. Insurance companies were at the forefront of this effort, as were employers who found themselves paying workers' comp. premiums in excess of 50% of payroll in many cases. I'm not kidding: Pay a guy $500 for a week's work, and send the insurance company $250 for workers' comp coverage. Keeping loggers out of the hospitals and morgues was (and still is) a big money deal.

    Anyway, what the Swedes introduced is a concept called "open-face" felling. Take a look at the notch in the tree the guy in my avatar is cutting. He makes a big, relatively shallow notch, aka a "90-degree open-face notch" that goes into the tree not more than 1/4 of the way. This is followed by a back-cut even with the bottom cut on the notch. Not above and not below. The back-cut should go into the trunk of the tree about 2/3 of the diameter, but under no circumstances should it sever the hinge, which is an inch of two of uncut wood holding the tree to the stump. If the tree doesn't start to fall on its own, you will need to insert a wedge or (on smaller trees) a felling lever to push it over in the right direction. The hinge will restrain the tree so that it can only fall in the direction of the notch. If you cut the hinge or it breaks before the tree hits the ground, you've lost control of it. That's dangerous.

    As elk points out, once the tree starts to fall, you move away from the stump at an angle. If the tree is falling at 12:00 o'clock, in other words, you retreat towards 8:00 or 4:00 o'clock. Before you started cutting the tree, you should have cleared an escape path so that you can get to a safe distance (say, 10 yards) before the tree hits the ground. The reason for retreating at an angle is in case the tree bucks straight back when it hits the ground. Once you're sure everything has finished falling, go back and cut the hinge loose, but be aware that the butt could (and often does) rise straight up when you release it.
  8. Mo Heat

    Mo Heat Mod Emeritus

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    Eric, I have an additional question for you. Once the tree starts to fall, should the sawyer...

    turn off the saw and set it down?
    turn off the saw and walk away with it?
    set the saw down still idling?
    walk away with the saw still idling?

    Living here in Missouri, I also have to wonder if Tom Sawyer was a lumberjack? :)
  9. Eric Johnson

    Eric Johnson Mod Emeritus

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    I grab my saw and walk away from the falling tree. If your saw becomes stuck in the cut, then abandon it. It's not worth risking your life for a saw, but if there's any way to safely take my saw with me, then of course I will. A falling tree will do nasty things to anything that gets in its way, and includes both you and the saw.

    As to shutting it off, I don't do that. It's probably a good idea to engage the chain brake, but I don't do that either. I figure if it's safe for me to walk around with a running saw, it ought to be safe to retreat from a falling tree with a running saw. I don't run, by the way, but I don't lollygag around, either.
  10. JAred

    JAred New Member

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    Not to mention many new saws have throttle safety buttons so you don't inadvertently hit the throttle. My chain does not turn when at idle. Not to say someone isn't using a saw without a throttle safety or a saw that has an idle set too high.
  11. ourhouse

    ourhouse Minister of Fire

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    A good rule of thumb I try to teach anyone new or looking for improvement is that if you have to take more than 2 or 3 steps with a saw then lock the chain brake. Locking the brake only takes a fraction of a second to do each time. I know in the game of logging they want you to do it even if you take more than one step for safety. When I'm cutting a tree down after it starts to go over I always lock the brake and shut the saw off while using my preplanned and cleared escape route. Sometimes, depending upon terrain and weather conditions, I lock the brake then shut the saw off and put it down utilizing my escape route. Saws are replaceable but people are not!
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