Angled back cuts

[brendonv]

I am speaking of the typical "homeowner" cut. Notch it then do the angled downwards back cut. I know this is wrong, I see it often and would like to tell them why it's wrong with a educated answer. And I don't quite have the answer.

Anyone up to schooling me? :)

[MasterBlaster]

Just tell them "NO."

[sawinredneck]

I did this on a large codom Hedge tree thinking it would stop barber chair.
I did about everything else as wrong as wrong can get!! I ended up BELOW the bottom of my notch and if it weren't for wedges, and lots of them, I was SCREWED!!!!!
I got really really lucky!! I forget why else not to do it, but that was enough for me!!

[NickfromWI]

I've read (but don't know for a fact) that the angled back cut increases the chance of barber chairing.

love
nick

[sawinredneck]

I've read (but don't know for a fact) that the angled back cut increases the chance of barber chairing.

love
nick


Did I forget to mention I was "thinking" that day?

[Skwerl]

The reason it doesn't work is because it doesn't allow the feller to make an accurate hinge. Felling isn't about what you cut, it's about what you don't cut (the hinge). The angled back cut is made by fellers who do not comprehend that concept. They somehow believe that the action of cutting somehow steers the tree. Once a feller fully comprehends the concept of hingewood then he is much less likely to continue using a sloped back cut.

[NickfromWI]

You could also refer them to "The Fundamentals of General Tree Work" chapter 25, "The Backcut."

Simply point out that the angled back cut is not even mention in this extensive masterpiece.

love
nick

[Stumper]

Besides the greater difficulty in having the finished back-cut line up properly with your face for the intended hinge the principle problem arises when using felling wedges...instead of all of the force from driving your little pocketable inclined planes being directed vertically to lift the back of the tree and TIP it forward, some is driving the tree forward. That doesn't sound too bad but it may cause a hinge to fail prematurely,driving the butt forward and allowing the tree to trip backward. At best it is simply less efficient than a level backcut.

[lumberjack]

Furthermore, in a wedging or sit back condition, the forces are working with the grain as opposed to against it. What can very well happen is the stump splits, and that is the start of a bad day.

[brendonv]

My instinct was that it did affect the hinge properties. Seems like I was on the right track.

Thanks

[sawinredneck]

Furthermore, in a wedging or sit back condition, the forces are working with the grain as opposed to against it. What can very well happen is the stump splits, and that is the start of a bad day.

EVERYTHING that day was BAD!!! I totally had my head up my butt that day!!!!
It did set back on me, and I was ready to run!! I think about six or eight inches of the butt was sitting on the back side of the stump. It was a heck of a clean up!! Not sure how familiar you are with Hedge trees, but nothing grows straight!! It would have been really nice to had that 36" tree sitting on the ground and not worry about which way it was going to roll off that stump!!

[Old Monkey]

People think that an angled back cut will make the tree go in the downhill direction. The only way it works is if the tree leans that way already or if it is a small tree and they turn their bar in the cut. What they don't realize is that when you cut through a tree you are removing a strip of wood that we call a kerf. The kerf is in a sense a face cut and causes the tree to want settle towards the side you are cutting on unless the lean is away from the cut. The slope of the cut does not matter as a level kerf and a slanted kerf will react just the same. The tree doesn't "feel" the slope, it only knows that you've removed the thickness of your kerf from one side of the tree.

In your scenario someone put a correct face cut but then used a slanting back cut. The reason the slanting back cut is wrong is because:

1. The angle doesn't make any difference to the tree.

2. Cutting at an angle is slower which gives the tree more time to barber chair if it is going to. On heavy leaner you need to get through the wood quickly.

3. Where you finish you back cut is important and cutting on a down slope makes that much harder to get right. Judging correct stump shot and an even hinge while cutting a down sloping back cut is tricky.

4. If the tree settles back on your saw in the back cut, wedging will be difficult to impossible.

I hope that answers your question.

[sotc]

darins number 4 is what i usually think of. your wedges are pushing into the hinge instead of lifting the tree. like trying to open the door by pulling the knob toward the hinge instead of the normal 90 degrees from the hinge

[gf beranek]

Yeah, angled backcuts don't do it too well. For so many valid reasons already mentioned.

The fact that so many people have used them and still do makes me wonder how the logic is passed on.

Is there some secret "layman knowledge" that we're all missing.

[GASoline71]

If you have to wedge the tree at all... it will try to push the spar off the hinge, insted of lifting the spar in the intended direction. So it works against your hinge wood.

There are a lot that also think it is going to save them from stump shot... but it will just make the butt kick up higher.

Main reason I see is you don't have as much speed and control when doing an angled back cut. Think about when you are making a proper face cut you are coming through the grain of the wood at an angle. Even with a laser sharp chain you usually are throwing a lot of saw"dust" instead of chips on an angled face cut. It takes a little more time.

When you make a proper back cut (or when you make the gunning cut in a Humboldt) notice that you are tossin' nice chips with the saw chain... your cut is smoother, more controlled, and when you need it to be... faster. You're cuttin 90 degrees from the grain of the wood.

It just compromises way to many things in a proper 3 cut.

This topic came up over at AS... and the certified fallers in BC chimed in and said that is illegal up there to make an angled back cut. Prolly not illegal for homeowner Billy, but for the pro guys yes.

Gary

[Bounce]

You should always make your back cut level and about 1-2" above the level plane of the face cut (notch) in order to leave a surface that the tipping trunk can push against to prevent it from sliding back over the stump towards the sawyer. As the tree is falling, the butt is getting pushed by the top in the opposite direction the top is falling in. If the back cut slants down towards the face cut instead being slightly above it, you've created a ramp for the butt to slide up towards yourself as the tree tips over. This isn't quite the same as a barberchair though because the wood hasn't actually split or broken. As I understand it, a barber chair is when the trunk actually splits along the grain sending the part above the back cut towards the sawyer, usually due to a heavy lean and/or brittle wood. The effect is the same though, which is pretty bad - people and trees are about the same relative size as baseballs and bats.

I think the Fundamentals of General Tree Work should be required reading, especially the section on falling techniques. This was my employee training manual when I first got started, and I had to pass a written test to prove I had read it (all 500 pages) before I could even show up on a job site. I've never seen another source of info on felling techniques that was 1/2 as good.

[NeTree]

Furthermore, in a wedging or sit back condition, the forces are working with the grain as opposed to against it. What can very well happen is the stump splits, and that is the start of a bad day.

Precisely.

[Burnham]

Yeah, angled backcuts don't do it too well. For so many valid reasons already mentioned.

The fact that so many people have used them and still do makes me wonder how the logic is passed on.

Is there some secret "layman knowledge" that we're all missing.

I'll just tag on to Jerry's post with a ditto.

It truly is a curious thing, how so many folks do this. I wonder if it isn't just some vague idea that goes like "I know there's supposed to be an angled cut in here somewhere...". I don't think logic, even faulty logic, plays any role at all :).

[Stumper]

Burnham- It is also like topping-Tree stuff done wrong shows up better than tree things done right. Thus Joe Nonothing notices the bad and emullates it. I can show you sections of Colorado forest where virtually every tree harvested was taken with an angled backcut. Those stumps stick up saying "Look at me. Cut it like this."

[Mike Maas]

Precisely.Exactly. :D

If the back cut is slanted enough, just the weight of the spar sitting back can split the stump and let the tree fall back.
And if you have to wedge the tree, the wood just bends or splits and the wedges don't have any power.

[Mike Maas]

If you have to wedge the tree at all... it will try to push the spar off the hinge, insted of lifting the spar in the intended direction. So it works against your hinge wood.

Gary

Let me think about that...umm...uhhh...Nope.
In that thread at AS, the egghead engineers did the math and it put more force on the tree, because of the greater distance from hinge to wedge, increased by the angled cut.
What math they failed to take into consideration was the weakness of the wood the wedge pushes against.
Where is Spyder when you need one of his long complicated explanation/drawings?

[MasterBlaster]

Kenny ain't been around in a while. :(

[Mike Maas]

Where is he?

[MasterBlaster]

You know as much as me.

[Stumper]

You know as much as me.

Butch, I think you just made Mike's year.:P

[GASoline71]

What math they failed to take into consideration was the weakness of the wood the wedge pushes against.

That is basically what I was tryin' to say... :)

Gary

[Mike Maas]

It was a funny thread watching those degreed engineers struggle with such a simple process. :lol:

[Rotax Robert]

Great post and answers guys, I can think of very little to add. About the only time a have used a slanted back cut (no face cut) is when I am in real small wood and am just stump jumping pecker poles to get them out of my way or thinning.

[Stumper]

Robert, Yeah, stump jumping little stuff doesnt warrant bending over.-Slash a backcut and twist the bar or give a little nudge with left hand or shoulder to get things headed in the right direction if needed.

[Banned by Squirrels]

Pro:

There's a very specific set of circumstances that I will use an angled back cut; IF I AM strapped into a straight stick that is a leaner, (cutting against the lean) IF I HAVE a tag line tied, and IF IT IS small wood that I have to be behind it. (because of the whipping effect)

My reasoning is that under these set of events the angled back cut will mitigate the risk caused by the "push back" effect at the cutting point and I feel safer having that protection.

.02

[Cedarkerf]

Let me think about that...umm...uhhh...Nope.
In that thread at AS, the egghead engineers did the math and it put more force on the tree, because of the greater distance from hinge to wedge, increased by the angled cut.
What math they failed to take into consideration was the weakness of the wood the wedge pushes against.
Where is Spyder when you need one of his long complicated explanation/drawings?
That math was how to take practical knowledge and make a mess of it by guys that would take 6 of em three hours trying to fell a 10 inch tree in the middle of a field. That thread was bizzarre.

[GASoline71]

It was a funny thread watching those degreed engineers struggle with such a simple process. :lol:


That thread was bizzarre.

I thought the same exact thing. :lol:

Gary

[rbtree]

Bump. My extremely skilled climber seems to think the sloping backcut is a good thing. While I disagree with his reasoning (mainly that the tree would be less likely to fall back, only sit back) he has been using it for years with no bad results. Reckon he's never used it with wedges....
As far as a tree going back, if its going to break the hinge and go back, I'm of the opinion that it makes no difference whether the backcut is level or sloped. But, here's a thought. I wonder if it would be worse, not better with a sloped backcut. Couldn't the forward force caused by the sloping cut make the hinge wood break off, and slide the butt forward, which of course would tend to make the trunk fall backward?

In my relatively limited falling experience, I've not had a hinge break and a tree go over backward. I have them go sideways a couple times...I do remember once, misjudging a 110 foot spindly 12 inch fir. no rope, no wedges, but it sat back so hard that, later, when we got it over, after managing to get a rope up a ways, the imprint of every chain rivet was in both sides of he cut! Good thing we got it, as my pickup--and the house-- were where it wanted to go....

Tain't for me, but, man, does he get hot headed when I try to say something.. Course I coulda been more tactful.

[MasterBlaster]

I'd say "That's stupid!"

[NeTree]

RB, the angled backcut can act as a force multiplier in it's own right; rather than the two faces in a 90 degree back cut closing and just putting pressure 90 degrees to the wood grain, the angled back cut can act as a splitting wedge against the stump by allowing the two angled faces to slide past each other, highly increasing the odds that if the tree sets back, the stump can split out, and keep the hinge wood from holding things together.

Angled back cuts are a noobie, bone-headed move, and I've cut plenty of them on purpose to illustrate the fact. (One of the nicer points of doing hand falling sub work is the access to literally hundreds of trees a day to screw around on.)

You can demonstrate this yourself, by using a two or three inch branch. Cut a notch, and then a 90 degree back cut, and bend it across your knee to pinch the back cut. Now do the same thing, except cut the back cut at say 45 degrees- and you'll see just what I mean.

[Gord]

The only time I make a sloping backcut is when I'm felling a stem that's too close to another stem to get a cut in flat and too small to bore.

99% of the time a sloping backcut is just the plain wrong way to do it.

[NeTree]

I should also add that in rare cases, you have to make a cut in the root flare where the grain starts to run at 45 degrees; and in those cases, the angle allows you to keep the cut parallel to the wood grain- preferable if you're going to be doing some heavy wedging.

I usually avoid that by simply cutting higher up.

[NeTree]

Gord, yes... that's a time when your options become limited. In that situation, the stem is usually leaning in the direction of fall, anyways, so the odds of setback (and the associated problem with the angled back cut) disappear.

[Stumper]

Be more subtle. Smile. Say "It seems like that might help control the tree until you start breaking down the input forces and angles and do the calculations. Then it turns out that it doesn't help and can actually create problems. I made a few of those cuts before I learned better."
Make the point without insult.... then if they argue, smile and say "You are fired.":D

[Al Smith]

To comment on a hinge breaking ,the only time for me was a bad leaner,too thin of hinge and stacking wedges . Not a good plan .--but the good plan to a bad plan was having a well planed escape route and being young and fleet of foot .

[rbtree]

Couldn't fire Dave, he's now a sub....plus he IS the best climber I've ever seen--at work anyhow. err, I should say at removals, as watching Greg Liu and Mark Chishom on the TreeHouse tree was great......and all Graham Mc did for me was wreck out a little 125 foot fir for craning later......in what was essentially tenny runners.....when i handed him a 335 Husky, he about used it to clean his fingernails.....

He's worked with Dan Kraus, former ITCC champ...he's faster.....incredibly sure of himself and competent....I thought I was good till I'd worked with Dave. but his backcuts? Ugghh...and when I showed him why I bore the center of the hinge on simple stick fells, he was unimpressed and ho-hum...

[Stumper]

'Twas only a joke- I woulldn't fire someone for a failure to understand felling physics so long as they weren't killing people or breaking things.

[rbtree]

Be more subtle. Smile. Say "It seems like that might help control the tree until you start breaking down the input forces and angles and do the calculations. Then it turns out that it doesn't help and can actually create problems. I made a few of those cuts before I learned better."
Make the point without insult.... then if they argue, smile and say "You are fired.":D

He actually tried to say the physics would be in its favor....which I don't see.....

he said, I've done it that way for ever...learned it from a old pro....don't care what Doug Dent says, Who is he anyhow and so what.....who cares if he certifies forest fire fallers......

[Stumper]

Butch was right. "That's stupid."

[rbtree]

paging Gerry, Burn and wiley.......errr, you too Graham....

get off that drilling rig and climb some more pecker poles...:P

[treesandsurf]

I got to meet Dave while I was out visiting Roger. Really nice guy and insanely fast removal climber from what I saw. Definitely knows his stuff that was obvious. Makes me curious how such a competent climber could advocate for slanted back cuts... Hmmm?

jp:D

[sotc]

sounds like he stopped learning somewhere along the way

[stig]

But, here's a thought. I wonder if it would be worse, not better with a sloped backcut. Couldn't the forward force caused by the sloping cut make the hinge wood break off, and slide the butt forward, which of course would tend to make the trunk fall backward?



Exactly!
You are setting up to stump shoot the tree, only when stumpshooting one omits the undercut and hinge, but the result will be the same.

[TheTreeSpyder]

The angled backcut gives several problems.

If you need to wedge, it pushes tree across hinge rather than rotate/ pivot on it. So, you take a shorter, more linear/non leveraged route/non-rotational to target giving less advantage of input distance to output distance(by taking more direct/linear route of force), and fight the hinge structure too(trying to push across it).

Also, the angled backcut makes a weak back stop against sitback. This is because sitting back (or wedging off); has a backstop across thinned piece of grain, rather than sitting back and force going down squarely into grain(if using a horizontal backcut properly). So, it takes more wedge force to push same load, and the backstop is weaker. We say horizontal, flat, but i think we all mean perpendicular to the grain.

i think the splitting at sit back comes from weak structures getting pushed across this slanted backcut, and prying the weakness apart. so, i don't think it happens on each occasion or species etc.

Also, as stated, it is harder to leave a proper hinge, steer with tapered etc. when using slanted backcut.

Now i have slanted backcut, when backside is against building etc., but minimizing the angle as much as possible; when i know i won't have to wedge. Can claim that the outreach of the backstop is farther from pivot of hinge, so can try to make case for more leveraged backstop, but; the backstop is so weakened as to nullify i believe.

[MasterBlaster]

The only time I make a sloping backcut is when I'm felling a stem that's too close to another stem to get a cut in flat and too small to bore.


Ha, so there IS a legitimate reason to use it! :rockon:

[rbtree]

thanks spidey...i forgot to page ya....well explained....

[Burnham]

Nothing for me to add. The case has been made. It's a stupid idea.