MasterBlaster
Administrator Emeritus
Adjusted? How do you "adjust" it?
What's the biggest problem you have with tree work, technique wise?
- Thread starter woodworkingboy
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M
Mr. Sir
Guest
Sorry, I guess I just assumed that you had more experience and did not require a detailed step-by-step explanation. My point is that the logic of making a higher back cut to increase hinge strength is flawed. Increasing or decreasing the height of the back cut will have no effect on the strength of the hinge. That is determined by its thickness. The reason for making the back cut higher than the face is to prevent the tree from kicking back off of the stump.
woodworkingboy
TreeHouser
- Thread Starter Thread Starter
- #53
My original post about higher back cuts, as stated, was applied to when initially pushing over back leaning pine trees. The higher back cut with the more flexible wood species of yellow pine (what I was cutting), allowed a greater amount of fold before the hinge snapped. In many instances, the hinge held until the wide face completely closed. That's my point about being specific, as opposed to just general statements. This hinge strength was sometimes further augmented by a gap as well.
If you have cut a lot of yellow pines, you can see that the fibers elongate and bend more than many other species. The wood strength charts also support this. I can see where a more brittle wood might not be so positively effected by a higher back cut, and no such claim was made.
If you have cut a lot of yellow pines, you can see that the fibers elongate and bend more than many other species. The wood strength charts also support this. I can see where a more brittle wood might not be so positively effected by a higher back cut, and no such claim was made.
darkstar
Rockclimber/ treeclimber
Speaking of bidding ...
Yeah its low ball city.
This one guy always asking me for advice.What should i buy a bucket truck or a crane?
He dont know squat about tree work.
So i help him figure some things out and he buys a bucket truck parks it right near my truck with his sign on it .
All of a sudden hes a tree service
Haha boy has he got a lot to learn.
from the looks of his 73 model death bucket i recon he wont last a year.
But during im sure ill see some lowball bids outta him.
T
The Branch Doctor
Guest
T
The Branch Doctor
Guest
Speaking of bidding ...
Yeah its low ball city.
This one guy always asking me for advice.What should i buy a bucket truck or a crane?
He dont know squat about tree work.
So i help him figure some things out and he buys a bucket truck parks it right near my truck with his sign on it .
All of a sudden hes a tree service
Haha boy has he got a lot to learn.
from the looks of his 73 model death bucket i recon he wont last a year.
But during im sure ill see some lowball bids outta him.
Ha! I came across a guy like that a few months ago.... He's already given up and moved on. I guess tree work was too hard and scary for him.
Burnham
Woods walker
I don't agree completely with your assertion here...as Stumper said, a reasonably higher back cut provides a more flexible hinge. That may not equate to "stronger", but it does make for a hinge that functions better, to some degree. Lots of variables, but in general I'm with Jay and Justin on this one. Of course, I do agree with your reference to stump shot.
Brett, how in your view does it make for a less predictable hinge?
Burnham
Woods walker
Well.... I'm not 100% sure. I'd love to know myself.
So what tells you that it needs "adjustment? I've only replaced a Bigshot rubber once, and it seemed straightforward. The only thing I tried to do was make sure that the pouch hanging free didn't have any twist to it, that is, it hung square to the arms. I did that by turning the ends of the rubber slightly on the arms.
I don't know if that was some trick or not, just seemed logical, but it shot the same as before, from the first, after replacement.
Originally Posted by MasterBlaster
Adjusted? How do you "adjust" it?
Adjusted? How do you "adjust" it?
You turn the rubbers on the shafts a bit....sounds horrid doesn't it?Well.... I'm not 100% sure. I'd love to know myself.
M
Mr. Sir
Guest
As the height of the back cut is increased above the face cut, there is a point (which will vary depending on species, decay, etc.) where the hinge loses its effectiveness simply because it is too tall. I may not be explaining this in a way that is understandable (I know what I'm saying, but I'm afraid I'm not conveying it properly). In other words, the hinge will no longer act like a hinge. Does that make sense?
Burnham
Woods walker
Nope. Not to me, anyway.
We're not talking about a foot high hinge, just a few inches at most.
We're not talking about a foot high hinge, just a few inches at most.
M
Mr. Sir
Guest
I'm not sure I understand what is meant by a "more flexible hinge" and how this can be achieved by raising the back cut higher above the face. 
Burnham
Woods walker
As the tree leans forward on the hinge, a slight vertical split all along the rear of the hinge usually occurs, allowing more flex in the hingewood.
M
Mr. Sir
Guest
Assuming that's true, how does the height of the back cut change the amount of flex? That's what I'm not getting.
M
Mr. Sir
Guest
As I try to wrap my mind around this, it seems that more flexibility would occur if the back cut were even with the face.
Burnham
Woods walker
That difference in height is what allows the split to occur. If the apex of the face and the back cut are at equal elevations, there in no place for the front of the hingewood to move forward into, so the split is restrained by the whole width of the tree.
sotc
Dormant hero!!
think about a pencil hanging off your desk. lay a book over it even with the edge of the desk then as close to the desk as you can get push down on the pencil till it breaks. now get another one and do the same thing except push down as far from the desk as you can, youll see it bend alot befre it breaks
M
Mr. Sir
Guest
sotc
Dormant hero!!
by bending, the longer something is the more flex it has
M
Mr. Sir
Guest
I see what you're trying to say and in theory it sounds good, but in real life hinges don't work that way. In my experience, a "taller" hinge, i.e. a higher back cut, results in less flexibility; in other words, the hinge tends to "snap" rather than bend. I see more flexibility in a back cut that is even with the face or just slightly above. How many times have you seen a high back cut that actually overlapped the face cut; there is no hinge!!!
Dave Shepard
Square peg, round world.
I'll show you some poplars that will bend all the way to the ground, and not snap, with a little bit higher back cut. I think tree species may have a lot to do with it.
Burnham
Woods walker
That's neither here nor there, Brett :roll:. We're talking about a properly formed hinge, not one that's cut off the stump by an incorrect back cut. Of course there is no flex in that case
.I guess we'll just have to agree to disagree
...and for sure Dave has a valid point about differences between species being a factor.
sotc
Dormant hero!!
you still stop your back cut the same depth weather its level with the face or a couple inches above. if you overlap the face you essentially made a snap cut, no hinge in a snap cut
With the high stumps common in the US, you can almost always be sure that the woodfibers are running straight vertical.
When making face cuts as low as we do here, one always has to be aware of fibers running out towards the face. That means that the higher the back cut the weaker the hinge will be, because the fibers run across it. You compensate for that by making the hinge thicker.
With straight running vertical grain an elevated backcut will always make for a stronger, more bendable hinge.
That you, Mr. Sir says that in your experience the opposite is true, makes me wonder: exactly how much experience you have and especially, with what species of trees?
When making face cuts as low as we do here, one always has to be aware of fibers running out towards the face. That means that the higher the back cut the weaker the hinge will be, because the fibers run across it. You compensate for that by making the hinge thicker.
With straight running vertical grain an elevated backcut will always make for a stronger, more bendable hinge.
That you, Mr. Sir says that in your experience the opposite is true, makes me wonder: exactly how much experience you have and especially, with what species of trees?
woodworkingboy
TreeHouser
- Thread Starter Thread Starter
- #75
As I mentioned in an earlier post, the reason for the higher than usual back cut, was because we were pushing over back leaning trees with a excavator, and the height reach was limited. Most of the weight was above where the bucket contacts the tree. So, the requirement is to get holding wood at the hinge until the tree goes over, then still have holding quality to hit the lay. You go with a normal height back cut and a large beefy hinge, the tree is more difficult to push over (I tried it), possibly breaks prematurely, and the worst scenario is that it slips off the bucket and sets back hard and does damage...maybe kills the operator doing the pushing. At best, you can figure a lot of wood pull damage.
Two days of falling a large number of trees, informed that the higher back cut gave the compromise to get the tree over easily enough, while still having decent holding quality at the hinge. It isn't an ideal situation with the low push on the trunk, there is an element of risk, so I had to make adjustments.
The species of tree is a factor, yellow pine is pretty resilient and stringy wood that bends well before it breaks. The grain is straight, a factor that Stig mentioned, so odd runout at the tall hinge is not a concern, like it might be in more irregular grain trees.
Two days of falling a large number of trees, informed that the higher back cut gave the compromise to get the tree over easily enough, while still having decent holding quality at the hinge. It isn't an ideal situation with the low push on the trunk, there is an element of risk, so I had to make adjustments.
The species of tree is a factor, yellow pine is pretty resilient and stringy wood that bends well before it breaks. The grain is straight, a factor that Stig mentioned, so odd runout at the tall hinge is not a concern, like it might be in more irregular grain trees.
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