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Sloping Back Cuts - Why Not?

Discussion in 'Forestry Community' started by Philbert, Aug 19, 2016.

  1. Philbert

    Philbert Chainsaw Enthusiast

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    I 'know' that a sloping back cut for felling trees is 'wrong', but I was trying to better understand why, in order to explain it to others. Most of the references I found mostly said 'don't do it', with little explanation. So I tried to pull together what I could, from several sources. Please let me know if I am getting it, and help me to better understand the 'why'. Pretty basic graphics.
    Screen shot 2016-08-19 at 8.24.09 PM.png
    Some comments said that it was harder to hit the spot where you want the hinge to stop (typically about 2" higher than the horizontal face cut, and about 10% of trunk thickness) with a sloping back cut. You also cannot thin a hinge, if needed, without going below the stump shot shelf.


    Screen shot 2016-08-19 at 8.24.24 PM.png
    Other comments noted that when wedges are used in a conventional cut, they lift the tree, pivoting it on the hinge, and pressing down flat against the stump. When wedges are used with a sloped cut, they also push in a horizontal direction: this can cause a barber chair-like blowout at the rear of the stump, allowing the tree to fall in that direction. Several comments indicated that the forward direction of wedging also damaged the hinge.

    Does this make sense? Am I off-base? Anything else going on here?

    Thanks for any input.

    Philbert
     
    Last edited: Aug 20, 2016
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  2. Gunn

    Gunn Yay sawz

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    You're correct, sloping back cuts put pressure on the hinge and you lose lift.
     
  3. old guy

    old guy Super OPE Member

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    Besides that you'r making a longer cut for no advantage.
     
  4. bigbadbob

    bigbadbob Pinnacle OPE Member

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    Humbolt cut here,,,the forestry law,,in British Columbia.
    BBB
     
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  5. junkman

    junkman Crush it

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    Great explanation ,wedges are made to lift the tree like a strait back cut does ,not push the tree over like a slope cut does .

    The slope back cut can go over backwards and come at you if the hinge breaks also .
     
  6. Mastermind

    Mastermind Knocker Of Farts Staff Member

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    Very good thread Philbert. Thanks for sharing sir.
     
  7. Hinerman

    Hinerman ONE OF THE GREATEST!

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    I asked this question on AS. Here are a few good answers:

    1) From Bitzer: Regardless of where you remove the wood you are still removing the wood, meaning in what way would a sloped (farmer) back cut help propel the tree forward? The biggest problem (other than it looking just plain dumb) is that if the tree sits back and you try to wedge it you can blow the back out because the pressure and strain is on the wood behind it and not on the stump. Instead of lifting vertically you are pushing horizontally. Also if it sits back it will put extra strain on the hinge wood and can break off and fall one way or the other. There is greater leverage on a sat back sloping cut than a flat cut. Kind of like putting a block (fulcrum) under a pry bar when trying to lift something.

    2) From Northman Logging: I guess to add... with a sloping back cut and wedges you can split the stump wood out, causing many bad things, having a level back cut puts the cut perpendicular to the grain and therefor the compression strength of the wood, when using wedges you will be far less likely to split it out or just plain have the wood absorb the wedge, or worst case scenario if the tree sits back on your saw, you have the compression strength, rather then the easy to split of going with the grain, and the tree will most times hang out there until you can figure out how to stuff a wedge in there, as long as there is enough holding wood...

    Also it can be very hard to judge how much holding wood you have left, lots of funny angles lead to optical delusions. making it very easy to overcut, or undercut the back. Both can be bad news, leading to barber chairs or side/back falling.

    3) From Bustedup: There are a few good reasons for not angling a back cut .........if ya gonna wedge then the action that you want of the wedge will be negated by the angle....ie instead of lifting up and forward there by committing the stick to the face it is forcing downward and will not be as effective indeed may actually bust the hinge if it a thin one (and that ain't good lol.....)

    Also you will somewhat lose the intended function of the hinge

    Ya can also get into the way fibre pulls and different species react etc

    Also if ya bored out the back and release the strap downward ya might lose yer saw rapidly lol

    Also sloping a back cut can be like sawing a lean in the back of the stick and depending on the balanced (ie where the hinge is how deep the face etc) you could negate the face totally and induce the stick to go backwards
     
  8. junkman

    junkman Crush it

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    If those guys say something,i listen and take in all i can ,they know their stuff.
     
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  9. KenJax Tree

    KenJax Tree ¯\_(ツ)_/¯

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    I've seen the tree sit back against the slope and the force at the bottom of the cut broke the holding wood causing the bottom to slide out and tree fell backwards
     
  10. Mastermind

    Mastermind Knocker Of Farts Staff Member

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    Just don't do it. Period.

    :)
     
  11. Hinerman

    Hinerman ONE OF THE GREATEST!

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    Funny you say that. Here was Gologit's response (only 4 words):

    "Sloping back cuts? No!"
     
  12. Hinerman

    Hinerman ONE OF THE GREATEST!

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    I have a friend that does tree work on the side. He climbs and rigs a lot of limbs so I would say he is "experienced" but not a "professional". I was on a job with him because I get wood from him for my firewood business. He had all the limbs down and went to drop the trunk. He notched it and went to do the back cut. Guess what back cut he was using......the sloping back cut. I said, "What are you doing with that back cut?". He said "I learned this back cut from a professional and it will get the tree to fall in the direction I want it to". I said "No you didn't and no he's not and no it won't". He gave me the stink eye. I talked him into putting a rope on it so a couple of us could pull in the intended direction. We got it down without a problem.

    Anyhow, I later provided him with some of the responses above and told him to search "sloping back cut or farmer cut". He became convinced it was wrong and thanked me later.
     
  13. Philbert

    Philbert Chainsaw Enthusiast

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    Some guys want to understand.

    The appeal of the SBC is apparent - it looks like additional insurance to prevent the trunk from slipping backwards off of the stump. A lot of things in tree cutting (and other occupations) are not obvious, but are learned the hard way over time. Some only apply a small percentage of the time, but when then do apply, may prevent catastrophic results.

    If we understand the reasoning, as well as the practice, it reduces temptation to disregard, or to consider those things as 'superstition', 'out of date', 'old wives' tales', etc.

    Thanks for all the input.

    Philbert
     
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  14. bwalker

    bwalker Pinnacle OPE Member

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    Timber falling: A Procedural Approach by Dent is a good read. It explains why a sloping back cut is a bad idea and many other things to avoid. Everyone should read it that falls trees.
     
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  15. so il logger

    so il logger GFY

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    A sloping back cut is ridiculous. Some farmers here think by doing that it is propelling the tree toward the intended fall.

    IMO by using it the hinge is bound to fail. Especially if the tree sits back, all that slope will do if that happens is force the lower trunk nearest to the kerf towards the face... Inevitably breaking the hinge and the tree falling backwards to speak.
     
  16. so il logger

    so il logger GFY

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    Plus I like flat stumps with no hinge... ;)
     
  17. Mastermind

    Mastermind Knocker Of Farts Staff Member

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    Stump jumper.
     
  18. 295 tramp

    295 tramp Hillbilly Saws

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    Thanks for sharing Philbert:thumbup:
     
  19. so il logger

    so il logger GFY

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    I have been called that before ;) lol
     
  20. ajschainsaws

    ajschainsaws Old enough to know better too old too care

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    Excellent thread the sloping back cut if wedged pushes the downward force the same angle as the cut which will go too the weakest point either front or back every time If it's an old hedge tree with big lateral lower limbs and a bit of but rot in the centre no control what ever More than likely to push it off the hinge and a backward fall

    At least with a straight back cut , the wedges are taking the place of the wood that's been cut with the saw , and your not putting pressure on the tree only supporting it until you get closer to the hinge , its your call to get the wedges home in the direction you need , and you won't need a neck like an owl too see which way the suckers going
     
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