Back cut safety question

[tbrickner]

Hi folks:

A quick safety question on macking a back cut.  I have seen different thoughts on this and wanted to get peopled opinion.  Once you make your notch in the tree and start making your back cut, should the back cut height be at an even level with the point of the notch or about an inch or more level above the point of the notch.  My feeling is that it should be about an inch or more above the notch.  Are there any variations on this based on conventional notch, open-face notch, or humbolt notch.

Tom

[Ianab]

An inch or so above the notch is the recomended place.

The hingewood mechanism works better and I think it lessens the chance of the butt jumping backwards off the stump when the hingewood finally lets go it you have that little ledge there.

Ian

[blaze83]

there are a lot of threads here discussing the various techniques for making your back cut, and over all felling techniques. as a general rule i try to use about 1 inch per foot of tree diameter ....not always of course, depends on the tree but in general  that is what i use.


Steve

[Meadows Miller]

Gday

I use an inch per oot like blase said humbolts i use on steep sites then usually trimm the hingewood off if theres no grain pull into the log 

Chris

[WildDog]

I agree with Blaze and Chris, my method following the completed scarf is to determine the thickness of the hinge, if I am chasing a 2 inch hinge and a back cut 2 inches higher than the top of the scarf, with the nose of the saw I put a shallow vertical cut (through the bark and into the sapwood) about 2 inches out from the scarf on both sides, I then sit saw dogs in one vertical cut (guide) 2 inches "Up" from the scarf, this gives me a starting point exactly the height I want my backstrap to be and if my back cut is 180 degrees and ends in the other vertical cut it ensures my hinge is the same thickness the full length, as soon as I can I get my wedges in. As Chris eluded to with our eucalypts we can a lot of fibre pull  

[maple flats]

A am about like Chris. I also cut my hinge after the notch (using a plunge cut) and cut out the back on trees big enough to do that. If a wedge is called for (and it is unless there is some forward lean) I cut a plunge cut (or 2) for the wedge(s) and preload the wedge pressure and then finish the cut so the last bit cut before the fall is committed is the very back side. Doing this the free will not barber chair and you can get an even uniform properly sized hinge every time (I leave about 10% of diameter on most live woods, more if dead) . When the tree starts to fall you have already finished. I often see others chasing a fall to cut more and reduce the hinge size as a tree begins to fall. That is the time to get out on the best  of your pre determined escape routes, usually 45 degrees back. The tree then has much less chance of shooting back off the stump with the lip you left from the elevated back cut of 10% of diameter.

[John Mc]

What Maple Flats describes is a lot like what is taught in the Game of Logging classes: hinge thickness = 10% of DBH, hinge length at least 80% of DBH. (They do mention that you may have to vary the rule of thumb on hinge dimensions depending on species and other conditions.) Bore cut to start the back cut, and work your way back from there. The only difference I recall is that GOL recommends having the back cut height match the "point" of your notch, rather than putting the back cut higher.

Leaving that last bit of "trigger wood" at the back of the back cut sure does help avoid barber chair... having the hinge all set before you cut the trigger avoids the problem of the tree starting to fall too early on a front leaner (as can happen if you start the back cut from the back and work your way in - tree can fall before you've got the hinge where you want it).

I do wonder about the debate between lining up the back cut with the "v" in the notch vs offsetting the back cut up a bit. I can't recall what the GOL guys gave as their logic for aligning it.

John

[beenthere]

............ The only difference I recall is that GOL recommends having the back cut height match the "point" of your notch, rather than putting the back cut higher.
..........I do wonder about the debate between lining up the back cut with the "v" in the notch vs offsetting the back cut up a bit. I can't recall what the GOL guys gave as their logic for aligning it.

John

GOL course I took did not line up the back cut with the notch. It was above.

Maybe just a difference in individuals teaching. But the printed GOL materials handed out have the back cut higher.  I haven't looked for those materials online.

Member Kevin has some good pics to illustrate, but he doesn't have a gallery, so cannot point you to them.

[Kevin]

The general rule is 1/10 the trees diameter for hinge thickness and 1/10 the trees diameter above the apex for stump shot.
The more wood you leave at the hinge the more difficult it will be to wedge over and too much will cause the tree to split.
Too little and you could lose control of the tree.

[John Mc]

............ The only difference I recall is that GOL recommends having the back cut height match the "point" of your notch, rather than putting the back cut higher.

GOL course I took did not line up the back cut with the notch. It was above.

Maybe just a difference in individuals teaching. But the printed GOL materials handed out have the back cut higher.  I haven't looked for those materials online.

I have my printed GOL materials sitting in front of me. There is no good picture showing the alignment of the back cut to the notch, at least in my documents. However, the scoring system they use for the "5 point felling plan" phase (identify hazards, Determine side lean, determine escape route, determine hinge size, establish cutting plan) mentions in the "cutting plan" part that "The back-cut should be level with where the notch cuts meet and should be completed on the good side of the tree."

The copy of the MEMIC manual I downloaded a while ago (which seems to be mostly a clone of the GOL techniques) also says "The back cut should be level with the notch if the open face notch is used." (Leaving me to wonder if offsetting the back cut would be preferred when using something other than the open face notch.)

I'm not trying to argue they are correct... I'm not experienced enough to make that judgment. I'm just saying that's what they have in writing, and how they expected to see it done in the 4 GOL classes I participated in, so that has become my habit.

John Mc

[beenthere]

John
I tried to find a good answer too, but couldn't. And also, not trying to push one idea over the other. 

I did look at the OSHA standards, and found the "level" with the notch recommendation, but then found an addendum to that rec. which seemed to backtrack on their original "rule".

Much mumbo-jumbo in the wording to learn much from it.   

http://www.osha.gov/SLTC/etools/logging/sections/federalregister/backcut_fr.html

Guess I'd suggest do as one wishes. 

[Kevin]

The main reason for using stump shot is to help prevent the tree from coming back over the stump such as when felling up hill or when the top may hit another tree.
I make a habit of using it all the time.

[John Mc]

The main reason for using stump shot is to help prevent the tree from coming back over the stump such as when felling up hill or when the top may hit another tree.
I make a habit of using it all the time.

Now that makes sense.

Does anyone know why GOL (at least in my area) and some other sources push making the back cut level with the notch?

[Bruce_A]

I don't know what a "stump shot" is, but when I am trying to drive a row of leaners or low stump a stand I prefer a humbolt.  Same labor, cleaner look, safer day.

[Ianab]

Another thing is how accurate your cutting is.

Having the cut slightly above the notch is usually not a problem, the hinge still works normally.

Cutting below the hinge is setting you up for a premature failure of the hinge as the tree goes over.

So if you aim for an inch above, and end up someplace between level and 2" high (on a big tree anyway) then nothing bad happens.

The training videos allways show nice straight trees growing on flat ground. Plunge cutting into a 50" leaning growing on a 45deg slope, well it's not like in the pictures. Getting your 2 plunge cuts close to meeting, someplace just behind the hinge.. well you want to allow a couple of inches margin for error  

Ian

[Ianab]

I don't know what a "stump shot" is, but when I am trying to drive a row of leaners or low stump a stand I prefer a humbolt.  Same labor, cleaner look, safer day.

Stump shot is when the butt comes free from the stump and bounces back toward you. If you are on a slope, or falling into other trees, or even just cutting a tree with springy branches it can happen. Having a little step on the stump helps reduce it. It's also the reason that you move away at a 45deg angle from the stump.

Cutting a Humbolt notch isn't wrong in 99% of situations, but knowing a variety of cuts and what works best for different problems can only be a good thing.   

Ian

[GASoline71]

1" above...  A little more when I'm on a spot where my exit isn't all that great and I have to stay at the stump longer than I want.

It's all just a little added protection from the spar comin' back at you off the stump.

Don't matter the diameter of the tree...

Gary

[Kevin]

STUMP SHOT: Two inches or more height difference between the horizontal cut of the face and the backcut. The difference in height establishes an anti-kick step that will prevent a tree from jumping back over the stump toward the faller.


It does matter to the government when charges relating to an accident are pending.

[Dale Hatfield]

Howdy ALL  been gone for a spell.
GOL and all safety trainings I do we shoot for level at center of the notch.
This allows exact hinge thickness.Coming in above or below can look like you have an inch of hinge. but have less or more, depending on how the notch is placed. Having less can lose the tree to side lean or weight. Having to much can cause barberchair .
The osha rules were wrote her on the east coast. They had to add the diff for the strage ways of the west 

[Brucer]

The old convention was to have your back cut at least 2" above the horizontal face cut (i.e., the point of the "V"). The reason most often given is to create a stump shot to prevent the trunk from skidding back off the stump.

But there's another reason.  When the back cut is level with (or below) the point of the "V", the wood fibres in the hinge will break much sooner as the tree falls. With the higher back cut, your hinge can bend and will hold onto the trunk for more of its fall. You get much better control this way.

In ideal conditions it may not matter too much. When you've got wind, asymmetrical branches, or nearby trees the extra control can be a lifesaver.

Of course, if your face is too narrow, it will close too soon and tear the hinge free. Doesn't matter how flexible your hinge is in that case .