The difference between logging and Suburban Tree Work

chep said:
A full length hinge undoubtedly provides more control to a stem. I still can't quite understand why you choose 2 thick posts instead of 1 long (tapered if need be) hinge. I understand the outside 2 corners are really all that is needed for directional control, but why take the risk of removing the center, especially on urban trees where defects are plenty. It seems like a bit of chainsaw showmanship and wasted moves in that setting. In the woods where every inch of that veneer log counts and to get it on the ground without tearing, splitting etc the extra work pays. In someone's yard you are adding an additional what if. And I don't like it. You do you man, but I hope people aren't paying to much attention to your vids cos this is one that takes some serious technical knowledge. I think someone/something could get messed up.
I learned how to gut a hinge in 2013. So I've only been using it for 11 years on the regular. I have never used it in an urban setting. I still do tree work to stay current and sharp, but it's not my every day.
Be safe. This video was taken yesterday while cutting on a logging job.

P.s
Why you would take a running start on a pull tree with a front end loader sounds insane. Especially with the tree cut up amd standing on posts. I guess I'm playing a diff game then you Daniel.
Be safe
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Good explanation of the face plunge. For my application I only use it when I can't meet the cut on something stupidly large. If I was felling for timber value then I would certainly utilize it more.
 
@southsoundtree yes I have pulled pretty good size east coast timber with cables and skidders and big ropes and forwarders. I would never gut the hinge. one post failing puts a spin on the tree. It's way to sketchy for me.
Most of Daniel's vids are of spars that he has gutted the hinge and those don't bug me that much. I'll often nibble at the center of the hinge if I've cut got the tree cut up to where I don't want to cut any more off my corners. Essentially gutting the hinge after the fact. Mostly just on spars that have been stripped and don't want to fall. Sure I could have gutted it first, but I like to know what my hinge is made of before I make that choice. I'd rather know my corners are sound, then nibble. Be safe out there
 
Well, curiosity and boredom got the better of me. I did the 1/3 10% configuration. Notch depth leaving hinge length of 80% DBH gets uncertain because of trunk taper/root flare - seems like it would leave the smaller weaker hinge of a 25% depth - haven't verified the numbers yet. OSHA was the only hard reference for 10%

The chords that make the hinge were 0.940 and 0.990 diameter - pretty damn good at getting the most support while balancing over/under center and wedging leverage.

I still haven't resolved choice of axis re 2nd moment of area because if you choose it to coincide with the neutral axis there's some intuitive advantage but it complicates the math, but for realistic analysis considering the unequal compressive and tensile strengths of the wood it might be necessary. For the first try I just chose the centroid axis. (resisting side lean)


1/4 pi r^4 whole circle Ibar = 0.0491 D^4
Ibar rectangle of hinge 1/12 b^3 h = 0.00692 D^4
I contribution of triangular ends of hinge based on 1/36 b^3 h and d^2xA parallel axis theorem
0.000572694 D^4 - the 694 is the bits about their own centroids and the 572 is d^2 A contribution
- those little bits contribute another 8% strength due to the magic of r^2!
add = 0.00749 D^4
%of original 0.00749 /0.0491 = 15.2% strength

Ibar remove center 1/3 1/12 b^3 h = 0.000256 D^4
%hinge strength reduction 0.000256/0.00749 = 3.4% surprising result magic of less r^2

I'm pondering the interpretation of these numbers. 15% rings true. Anyone want to translate the axis to the edge of the trunk using the parallel axis theorem? I new axis = I old axis + cross section area x (distance between axes)^2 Curious if axis choice affects the results


Worth noting hinge strength varies directly/1st power of hinge thickness and hinge thickness goes away as the fibers fail.
 
Bart_ said:
Well, curiosity and boredom got the better of me. I did the 1/3 10% configuration. Notch depth leaving hinge length of 80% DBH gets uncertain because of trunk taper/root flare - seems like it would leave the smaller weaker hinge of a 25% depth - haven't verified the numbers yet. OSHA was the only hard reference for 10%

The chords that make the hinge were 0.940 and 0.990 diameter - pretty damn good at getting the most support while balancing over/under center and wedging leverage.

I still haven't resolved choice of axis re 2nd moment of area because if you choose it to coincide with the neutral axis there's some intuitive advantage but it complicates the math, but for realistic analysis considering the unequal compressive and tensile strengths of the wood it might be necessary. For the first try I just chose the centroid axis. (resisting side lean)


1/4 pi r^4 whole circle Ibar = 0.0491 D^4
Ibar rectangle of hinge 1/12 b^3 h = 0.00692 D^4
I contribution of triangular ends of hinge based on 1/36 b^3 h and d^2xA parallel axis theorem
0.000572694 D^4 - the 694 is the bits about their own centroids and the 572 is d^2 A contribution
- those little bits contribute another 8% strength due to the magic of r^2!
add = 0.00749 D^4
%of original 0.00749 /0.0491 = 15.2% strength

Ibar remove center 1/3 1/12 b^3 h = 0.000256 D^4
%hinge strength reduction 0.000256/0.00749 = 3.4% surprising result magic of less r^2

I'm pondering the interpretation of these numbers. 15% rings true. Anyone want to translate the axis to the edge of the trunk using the parallel axis theorem? I new axis = I old axis + cross section area x (distance between axes)^2 Curious if axis choice affects the results


Worth noting hinge strength varies directly/1st power of hinge thickness and hinge thickness goes away as the fibers fail.
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That math is way over my head.. thanks for taking a crack at it... the only thing I would ask is that whatever area you are measuring to be removed from the center of the hinge, you add to the corner posts.. I get the impression that you do that, but not sure of it. Can you just report the findings in lay terms so I can understand it please... Thanks

Also do I have it right that when you measure the chord at the back of the hinge, 43.3%depth, (33.3% + 10%) it has a daimeter .99 of full diameter at the cut (virtually the same as full diameter) ? That seems like it could be correct even though .99 seems a little higher than I would expect.

Bart_ said:
Worth noting hinge strength varies directly/1st power of hinge thickness and hinge thickness goes away as the fibers fail.
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Maybe not so much of a consideration. By the time hinge fibers begin to fail, the tree has enough momentum to carry it to the lay as long as they hold "long enough"...
 
If you gain say 10% by fattening the hinge then immediately lose it in 5 degrees of motion the gain or compensation seems questionable. The problem needs another page of head scratching to quantify that dilemma.

.99 and .94 surprised me too. yes 33% + 10%xdia = 0.43
 
Bart_ said:
If you gain say 10% by fattening the hinge then immediately lose it in 5 degrees of motion the gain or compensation seems questionable. The problem needs another page of head scratching to quantify that dilemma.

.99 and .94 surprised me too. yes 33% + 10%xdia = 0.43
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Obviously we are taking complete guesses at the numbers on gain of strength, and amount of loss during ° of motion, but I would bet good money your estimate of 10% gain is well under estimated. And the factor I promote as most important is hinge thickness. Hinge thickness is going to make a huge difference amount of strength gained. In other words, you're going to get a lot more gain from leaving 20+% on the tension side than you will by simply taking a little out of the middle and addiding it to the corners on a thin hinge.

I AM going to guess that my fat tapered hinges have 2-3X stronger holding ability agianst side lean than a straight hinge of 10% diameter. That's 200% to 300% stronger. The you take that fat boy tapered hinge and throw in a sizwheel and center plunge and you're getting 4-5x strength. Just a guess of course and it could be way off.

The nice thing about video is that you can listen and hear the hinge pop when it fails to the side weight... And you can hear it squeaking and moaning along the way. When that squeaking and moaning ends, that's usually as far as the hinge held. You can get a pretty accurate sense of how your hinge holds from watching and lsitening to video in conjunction with stump fiber examinations. 5° isn't going to even start squeaking a hinge. If you throw in a sizwheel and 2-3" of stump shot, you're getting a lot of flex out of that post on the tension side. A LOT.. I would guess under 20% hinge strength loss through 20-25° of motion (when using the sizwheel). By that time the tree has enough speed and momentum to make the lay.

Then there is one other factor that a fat hinge allows which I won't mention just yet. Does anyone else want to take a crack at it? Obviously these numbers are spitball estimates. Was your number of 10% a guess or did you arrive at it through some calculation? If it's the latter, please explain your math. I think there are just too many variables for the math. And I trust my real world expereince over anything that could be put to pen and paper.

How many here have lost a tree to the side weight? How far did it move before the hinge failed?
 
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"say 10%" means 10% fatter hinge directly as stated above. first power of the dimension. to gain 300% you need 300% hinge fatness. I recall 10's of % fatter in your vids

center 1/3 removed small 3.4% reduction because acting at r^2 from the presumed center neutral axis/centroid

the strain (stretching) per degree of trunk tilt is also 1st power of hinge fatness as the fat dimension is the lever length that converts tilt motion to fiber stretch - fatter it overstretches (fails) earlier in the fall


Bad news in drawing a side loaded trunk the addition/conversion of normal stress and shear has really ugly math not the simple superposition/addition Terry Hale drew in his straight but yet side loaded tree trunk :( It's been 40 years since I was almost taught the ugly math so some patience or help is in order.
 
Bart_ said:
"say 10%" means 10% fatter hinge directly as stated above. first power of the dimension. to gain 300% you need 300% hinge fatness. I recall 10's of % fatter in your vids

center 1/3 removed small 3.4% reduction because acting at r^2 from the presumed center neutral axis/centroid

the strain (stretching) per degree of trunk tilt is also 1st power of hinge fatness as the fat dimension is the lever length that converts tilt motion to fiber stretch - fatter it overstretches (fails) earlier in the fall


Bad news in drawing a side loaded trunk the addition/conversion of normal stress and shear has really ugly math not the simple superposition/addition Terry Hale drew in his straight but yet side loaded tree trunk :( It's been 40 years since I was almost taught the ugly math so some patience or help is in order.
Click to expand...
I think you are making a flawed assumption that adding 10% more hinge material will only add 10% to the hinge strength... Take the example of a 20" DBH tree, standard notch and back cut leaves a 10% hinge. Hinge is 2" wide... set the pull rope at 50' height (arbitrary) and pull it over with 3 guys on the rope.... Now make that hinge 4" wide, and put 6 guys on the same rope... NO CHANCE.. if it takes three guys to pull a 2" hinge it might take 10 or 15 to pull a 4" hinge.... Double the size of the hinge is going to take 5-8x the pulling force to trip... again just a guess based on personal experience...
 
something that non-engineer’s don’t remember is the effect of the cubes and squares from pi on circular calculations Look at strength charts for various uniform materials See how things change.

The man power pull that’s referred to here isn’t a surprise for anyone with even a basic engineering knowledge
 
Gutted a hinge on a spar today, with a cut I invented.

It’s top secret so don’t share widely. Conventional face/back cut on a backleaner. Cut it to a thin hinge and wedged it over center. There wasn’t enough room in the back cut with the wedge and I was too lazy to walk back to the truck for an hour xtra wedge for stacking. Could have probably pushed it over but lazy still.
So I gutted the hinge from the face cut with the nose of the saw.
Wowwe folks are will be singing my praises for decades to come.

I call it a ‘don’t give a f-cut’ or DG/FC for those who like acronyms
 
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davidwyby said:
Flaw in the thick hinge theory?

More wood in compression means it cannot be compressed and it will act as a fulcrum to break the rear/tension wood sooner. Theoretically…
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Beating a dead horse here, or reminding...

When the tree is static, the thicker hinge on the tension side indeed is resisting the lean with more wood. However, as soon as we start to pull, the front compression half of the hinge starts to break the rear. Dry wood does not compress, bend, or pull as much as green. One would do well to employ a sizwheel and a triple hinge....might help a little. All relative, lots of variables, and just theory.
 
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