Sloping Backcuts?

[John Bearley]

Is there any reason to use a sloping backcut on a tree ~25" in diameter and a Conventional face? D. Douglas Dent in "Professional Timber Falling" decries it and gives a mechanical analysis of its faults when used with a Humboldt face. However there is an old local Vermonter that my father-in-law sometimes uses and looking at the stumps he seems to always use a sloping backcut and a Conventional face.

 

[Newfie]

I know people that always drive 80mph and don't wear seatbelts. Doesn't make them safe, just lucky.

Why would you want to use a sloping backcut? I can't see any advantages to it.

 

[Jacob J.]

<p>Howdy-<P/>
<p>Thinning crews here use sloping back cuts on steep ground so the tree will slide off the stump and go tumbling down the hill so it's out of the way. They're usually working in diameters under 16" though. D. Doug Dent is right, if you use a sloping back cut and then have to wedge a tree, the force of your wedge will actually be pushing the tree forward off the stump rather than lifting it straight up like with a horizontal back cut. Wedging in a sloping back cut also promotes barber-chairs.<p/>
<p>That Doug Dent is a great guy though, I met him on some Forest Service training years ago. He had his own helicopter fly him into the training site.<p/>

 

[ccooperabbs]

Gents,

Just reading your threads and the book "Professional Timber Falling" crops up, not the first forum where this publication has been mentioned, do you have any idea where i can get hold of a copy. Been UK based i would be prepared to reimburse costs if some-one can send me a copy, maybe email me off line.

[email protected]

Thanks

Pugsly

 

[StIhL MaGnUm]

Baileys is where I got mine

 

[crowe]

In almost any scenario sloping backcuts are bad practice. I have seen it used as Jacob mentioned and have been known to use it myself in the same situation. I have done it myself trying to get a tree to slide back down the hill so I wouldn't have to drag the cable up hill fifty feet to hook it up. Its bad practice and I always cussed myself for doing it. I saw a guy mash his foot several years ago doing something very similar and he lost three toes. Be carefull!..........Wade

 

[Gypo Logger]

Sloping backcuts are used successfully only when stumpjumping stems under 6-7" dia. A fast saw, a good eye, and a flick of the wrist does the trick. I became very adept at this while tree spacing Doug Fir on Van Is. B.C. I was known as the Wayne Gretzky of tree spacing then with my Husky 266.
John

 

[TheTreeSpyder]

Mr. Gypo, that does sound like the only reasonable mechanics, and acceptable source (you) for such i've ever heard for such practice! (see, i don't always have to antagonize the climber-logger stuff!!)

i've also read that coming thru the fibre at a slant on backcut is inferior by the way that the fibre releases instead of coming straight thru (never understood it, jsut read it!).

i kinda found myself sloping backcuts years ago; it does seem safer; kinda like you're not sure, and it seems safer like a large backstop. Even done it on something leaning slightly back from lean (with high, high leverage, braced line for pulling home); until reading contradictions.

Dent is the man! Took me a while to realize that chasing the forces into the face with patterned backcuts was the same patterns as same in bucking, only turned to whatever angle compression and tension of fibre was compared to face, as diagrams in chapters are pages apart. i've taken these lessons into the air, and they still test out wonderfully!! So now every cut places a face at workable position, preloads the opposing fibre specifically to lean with pre-backcuts, then come thru on final backcut seeking fibre in hinge to balance pulls of opposing lean side (or pushes from brushing trees on same side as thicker part of hinge); so that pulls across the face are balanced as hinge folds. Then also, faces slapping is balanced to serve out squarely into gunned face.

Unequal pulls during travel on hinge, or unequal (side to side) pushes at closing face; can quite logically compromise mechanically serving spar forward squarely into path of facecut.
It is all about balanced forces, or as close as you can bring them for safest, most predictable folding, IMLHO.

Just like moving anything else, if it is off balance, you must fight that off balance the whole time of motion, rather than all efforts just pulling spar home on hinge (making hinge stronger). i think that the first part of force calculation is direction, then how much. If direction is not right, it must be fought every inch. Kinda like moving a refrigerator balanced on a cart, or leaning off to one side of 4 wheel cart the whole time you are delivering it. Balanced will be less effort, safer, more productive; for there is magic in balance! You can feel it on a motorcycle, and see it in many things.


:alien:

 

[StIhL MaGnUm]

Good post Spidey Your right Dent is the man

Rob.