Thanks Glen, that did the trick.
John
John
Directional pull line for felling
- Thread starter Ekka
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tnttreeman
ArboristSite Operative
Leveraged pulling
I asked the question to the physics guys at the mad scientist site. They basically said there isn't a difference in force whethere tying to the top of the tree or through the crotch and back to the bottom. Their answer is:The <a
href="http://madsci.wustl.edu/posts/archives/1105976966.Ph.r.html)previous
answer still is applicable. The only modifications I would make to
that answer are that
a) if the rope tied at the bottom of the tree trunk does not slip
either at the tied end or in the tree's crotch, and
b) if the tree is stout enough that the tree trunk does not bend,
then there will be no difference between the two ways of tying the rope.
However, there are some ways that the two methods can be
different, but I hesitate to mention them because they are probably obvious
to somebody of your experience. Here they are, though, for the benefit of
other readers:
1) If the rope tied to the bottom of the tree trunk can slip at the
tied end then you will have to deal with that inconvenience.
2) If the rope can slip in the crotch of the tree then there is the
possibility that the tree trunk will be more likely to snap or bend, due to
the added compression on the trunk (in the vertical direction) between the
bottom of the trunk and the crotch.
3) If the branch, to the side of the crotch, around which the rope is
tied is not sufficiently stout then obviously it can break. The rope
in the crotch will not break the branches to either side of the
crotch as easily.
4) The rope in the crotch may have a tendency to split the tree
at the crotch, but I don't actually think that that is very likely.
Have I missed anything? Happy timbering!!!
John Link, MadSci Physicist
I asked the question to the physics guys at the mad scientist site. They basically said there isn't a difference in force whethere tying to the top of the tree or through the crotch and back to the bottom. Their answer is:The <a
href="http://madsci.wustl.edu/posts/archives/1105976966.Ph.r.html)previous
answer still is applicable. The only modifications I would make to
that answer are that
a) if the rope tied at the bottom of the tree trunk does not slip
either at the tied end or in the tree's crotch, and
b) if the tree is stout enough that the tree trunk does not bend,
then there will be no difference between the two ways of tying the rope.
However, there are some ways that the two methods can be
different, but I hesitate to mention them because they are probably obvious
to somebody of your experience. Here they are, though, for the benefit of
other readers:
1) If the rope tied to the bottom of the tree trunk can slip at the
tied end then you will have to deal with that inconvenience.
2) If the rope can slip in the crotch of the tree then there is the
possibility that the tree trunk will be more likely to snap or bend, due to
the added compression on the trunk (in the vertical direction) between the
bottom of the trunk and the crotch.
3) If the branch, to the side of the crotch, around which the rope is
tied is not sufficiently stout then obviously it can break. The rope
in the crotch will not break the branches to either side of the
crotch as easily.
4) The rope in the crotch may have a tendency to split the tree
at the crotch, but I don't actually think that that is very likely.
Have I missed anything? Happy timbering!!!
John Link, MadSci Physicist
The URI you provided (http://madsci.wustl.edu/posts/archives/1105976966.Ph.r.html) does not address a comparison of installation types. Perhaps you had another one in mind? That question/answer is the only thing I can find at that site using their search facility with the word combinations "pull tree" or "rope tree".
I disagree with your added conclusion #2. The tension between the top and bottom of the tree-to-rope contact points will exist whether or not the rope slips, else the need to securely fasten at the bottom would not.
Glen
I disagree with your added conclusion #2. The tension between the top and bottom of the tree-to-rope contact points will exist whether or not the rope slips, else the need to securely fasten at the bottom would not.
Glen
tnttreeman
ArboristSite Operative
I emailed them the drawing Mike Maas used on page 1 of this thread (#10) as the two tie in points. Also, the conclusion #2 is not mine but the physicist that responded to the question.
I only tie in at the top to pull, never to the base.
I only tie in at the top to pull, never to the base.
MasterBlaster
TreeHouse Elder
Concerning dead, fragile trees the "rope to the ground" method allows for the top breaking out, yet the pulline is still viable.
Gord
ArboristSite Operative
Good point there MB. The whole 'spar bending under load/crotch breaking under downward force' disadvantage to the fishpoled line is moot in all but a very few circumstances. For me, the ease of setting a fishpoled line makes it my more often used method.
In situations like these, wedges are an aid and a safety. The line is the key.
In situations like these, wedges are an aid and a safety. The line is the key.
i think that strategy allows higher leverage more confidentally, for that reason. Any elastic flex in top gives storage of force i think, and i'd think a double displacement, for sure advantage?
i think MM drawing should pull offset torque from the heavier and higher side; not towards it.
i think the over the top lacing is the best, for several differances that appear, in the subtle change of the mechanics as i see'em. The reaching over, more of a spin, arched input on an arched movment on hinge; that i don't think a linear pull would trace as well, delivering full focus of effort to the work path. i think the Mayhem Puzzle proved there is extra loading, and loaded points, in the line bent on the load. Minimally, we have created
a loaded bend, that desires to unload, come out, dump it's load/bend; in additon to any pull of the line. Whatever the linear pull is, that addition of desire must be more!
i think the pulling up from the hitch on the over the top lacing as the bend pushes down, tries to put spin on the spar. On any axis of pull/push, we can increase/decrease by adding direction of spin to that same axis.
The elasticity is increased by the increased length of the line, it is usable to pull in addition to efforts as spar moves forward;from it's stored energy. Though as Eric says it can get in the way trying to take up all the elasticity on short intake of comealong/hoist; especially if you are using pulleys to increase power/ decreasing distance of pull on top of elasticity needing more distance to be taken up. We've mounted the hoist to a Z-Rig on
anchor, tension Z, lock, then pull with device to fumble thru that one. This pretensions line without using cable/chain length.
The line behind spar, can further have a purchase of line sweated from it, to be maintained on the other side of the friction at top of bend, for more power at first flexxing too; that gives maximum hinge strength in response (no dutching). i believe the spar movement is more directly focussed forward with this technique, for not an increase of power, but better, focussed use; that alone could seem like an increase in power; like better bearings might seem. i believe these are the patterns of these things i see.
In Self Tightening Torque ; i try to show once again that any bent line invokes a multiplier to recognize/ use. such a change in mechanics without offset, msut give some differance. It is similar to me here.
If a linear motion has so much power, that same motion + any spin force on same axis, must be different.
That is just a start i guess!
i think MM drawing should pull offset torque from the heavier and higher side; not towards it.
i think the over the top lacing is the best, for several differances that appear, in the subtle change of the mechanics as i see'em. The reaching over, more of a spin, arched input on an arched movment on hinge; that i don't think a linear pull would trace as well, delivering full focus of effort to the work path. i think the Mayhem Puzzle proved there is extra loading, and loaded points, in the line bent on the load. Minimally, we have created
a loaded bend, that desires to unload, come out, dump it's load/bend; in additon to any pull of the line. Whatever the linear pull is, that addition of desire must be more!
i think the pulling up from the hitch on the over the top lacing as the bend pushes down, tries to put spin on the spar. On any axis of pull/push, we can increase/decrease by adding direction of spin to that same axis.
The elasticity is increased by the increased length of the line, it is usable to pull in addition to efforts as spar moves forward;from it's stored energy. Though as Eric says it can get in the way trying to take up all the elasticity on short intake of comealong/hoist; especially if you are using pulleys to increase power/ decreasing distance of pull on top of elasticity needing more distance to be taken up. We've mounted the hoist to a Z-Rig on
anchor, tension Z, lock, then pull with device to fumble thru that one. This pretensions line without using cable/chain length.
The line behind spar, can further have a purchase of line sweated from it, to be maintained on the other side of the friction at top of bend, for more power at first flexxing too; that gives maximum hinge strength in response (no dutching). i believe the spar movement is more directly focussed forward with this technique, for not an increase of power, but better, focussed use; that alone could seem like an increase in power; like better bearings might seem. i believe these are the patterns of these things i see.
In Self Tightening Torque ; i try to show once again that any bent line invokes a multiplier to recognize/ use. such a change in mechanics without offset, msut give some differance. It is similar to me here.
If a linear motion has so much power, that same motion + any spin force on same axis, must be different.
That is just a start i guess!
To my eye Mike; your over the top lacing, pulls straightest, has most loaded points from rope straight inline with target axis. Also, i think that if the loaded line between the bend and the hitch lays against the spar, it steadies, stabilizes, pushes forwards more focussed somehow. Also in this position, applying an arched input pull, into an arched motion; maintaining more of 'focus', conserving more of effort into work. In that way not giving more power, but using existing power to more advantage, by this focussed conservation of force to target.
i think the bowline at top, pulls slightly off center to spar, and would provide more pressure towards heavy side. Grabbing the larger fork, would be off center pull to spar, but could be used as a correction, dealing with the sidlean force, reeling it into target, rather than pushing further away (as with torque from pulling on smaller fork can i think) with any torque given from off center pull.
Great rig Dan! i think for truck pulls ya need to verify weight in truck, solid non-slip run of proper length, overwhelming force on your side, possibly redirct pull from top of tree to lower so reactive pull doesn't pull up on truck - losing traction; while giving a mroe rotational angle of pull then advancing truck angle. Deeper face, to lessen backlean.
At 45 degree calculation, and any margin for error; you are in kill zone. Equivalent to the fall - height of cut: if tied at top; as best case scenario.
In Dan's case; i might have considered 'comealonging'(actually preferring chainhoist myslef) tree as forward as possible, lock off; then finish with truck pull. Primary comealong pull can continue thru 1st phases of back cut. Alternatively using truck, lock off with a line. Then switch truck to alternate system. If no extra pulleys, pull thru a self tended friction hitch,; let it hold tension, as you relax truck and lock off line, get multiplying pulleys free to use on secondary pull to finish. This makes the secondary pull much easier, and gives some degree of safety. Also, you can lay or hang spar aginst the line, to give bent tension and keep pulling as tree advances, on that side.
The next biggest thing is to make sure the face is in no way Dutched. If it is, all the tension is going into increasing compression on this unconected space in front of hinge. You want total relief in front, so the only responsive force you casue increase in is hinge strength, of connected wood, that controls from the rear that you are manipulating with saw thru backcut. Not, forcing higherforce in disconnected compression, inside of face,that you can't alter with saw cutting forward to target.
i think the idea of a directional line is wrong in good wood generally. The direction of pull should be to the full releif of the gunned face; forcing the hinge stronger, to multiply your efforts to then steer against the distractions to target of sidelean etc. Correcting lean directly with line by countering lean to opposite side of target, generates the same leveraged force on spar, just not further running it through the hinge multiplier to let that higher number fight sidelean. Unloading the hinge tension with the line correction to counter lean, doesn't allow the hinge to work for you in that way.
A bent line always gives a multiplier, forces re-induced onto themselves are harder to trace, as in Mayhem, DdRT, martial arts etc. Bent Line Calculator
i think the bowline at top, pulls slightly off center to spar, and would provide more pressure towards heavy side. Grabbing the larger fork, would be off center pull to spar, but could be used as a correction, dealing with the sidlean force, reeling it into target, rather than pushing further away (as with torque from pulling on smaller fork can i think) with any torque given from off center pull.
Great rig Dan! i think for truck pulls ya need to verify weight in truck, solid non-slip run of proper length, overwhelming force on your side, possibly redirct pull from top of tree to lower so reactive pull doesn't pull up on truck - losing traction; while giving a mroe rotational angle of pull then advancing truck angle. Deeper face, to lessen backlean.
At 45 degree calculation, and any margin for error; you are in kill zone. Equivalent to the fall - height of cut: if tied at top; as best case scenario.
In Dan's case; i might have considered 'comealonging'(actually preferring chainhoist myslef) tree as forward as possible, lock off; then finish with truck pull. Primary comealong pull can continue thru 1st phases of back cut. Alternatively using truck, lock off with a line. Then switch truck to alternate system. If no extra pulleys, pull thru a self tended friction hitch,; let it hold tension, as you relax truck and lock off line, get multiplying pulleys free to use on secondary pull to finish. This makes the secondary pull much easier, and gives some degree of safety. Also, you can lay or hang spar aginst the line, to give bent tension and keep pulling as tree advances, on that side.
The next biggest thing is to make sure the face is in no way Dutched. If it is, all the tension is going into increasing compression on this unconected space in front of hinge. You want total relief in front, so the only responsive force you casue increase in is hinge strength, of connected wood, that controls from the rear that you are manipulating with saw thru backcut. Not, forcing higherforce in disconnected compression, inside of face,that you can't alter with saw cutting forward to target.
i think the idea of a directional line is wrong in good wood generally. The direction of pull should be to the full releif of the gunned face; forcing the hinge stronger, to multiply your efforts to then steer against the distractions to target of sidelean etc. Correcting lean directly with line by countering lean to opposite side of target, generates the same leveraged force on spar, just not further running it through the hinge multiplier to let that higher number fight sidelean. Unloading the hinge tension with the line correction to counter lean, doesn't allow the hinge to work for you in that way.
A bent line always gives a multiplier, forces re-induced onto themselves are harder to trace, as in Mayhem, DdRT, martial arts etc. Bent Line Calculator
Last edited:
diminishing returns
How high the rope should be in the tree is not dicussed. High is good but you reach a point of diminishing return if you try to place the rope very near the top of the tree. Above half way yes, but do you get any better pull if you go beyond 3/4 of the way to the top of the tree?
How high the rope should be in the tree is not dicussed. High is good but you reach a point of diminishing return if you try to place the rope very near the top of the tree. Above half way yes, but do you get any better pull if you go beyond 3/4 of the way to the top of the tree?
MasterBlaster
TreeHouse Elder
Yes.
Ekka
Addicted to ArboristSite
Hi all,
Hasn't this been a great thread. I have to research this vigorously becasue it's part of my task for Arb College. I have to have facts and be able to prove them.
I jumped onto a physics forum and asked the question and they reckon there is a difference. The top tie off will give the most leveraged force as all the energy is directed to the one point of the tree and will follow the line of the rope to the pulling point on the ground ... where as if the rope goes down the back it will create a vector and more downward force depending on the friction from the fork (rough bark smooth bark etc), the less friction in the fork the greater the vector will become. Fact is there will always be a vector created as long as there's tension on that knot at the base on the trunk.
Imagine replacing that fork with a pulley, you all know that the force on that pulley would be split between the direction of both ropes, well its the same.
I've done a bit of a diagram so you can see. We are now crunching some numbers to try and quantify the fact, the next step is to set up a model. What we will do is apply accurate tension on a line, tie off in the 2 ways described and measure the bend in the spar.
Hasn't this been a great thread. I have to research this vigorously becasue it's part of my task for Arb College. I have to have facts and be able to prove them.
I jumped onto a physics forum and asked the question and they reckon there is a difference. The top tie off will give the most leveraged force as all the energy is directed to the one point of the tree and will follow the line of the rope to the pulling point on the ground ... where as if the rope goes down the back it will create a vector and more downward force depending on the friction from the fork (rough bark smooth bark etc), the less friction in the fork the greater the vector will become. Fact is there will always be a vector created as long as there's tension on that knot at the base on the trunk.
Imagine replacing that fork with a pulley, you all know that the force on that pulley would be split between the direction of both ropes, well its the same.
I've done a bit of a diagram so you can see. We are now crunching some numbers to try and quantify the fact, the next step is to set up a model. What we will do is apply accurate tension on a line, tie off in the 2 ways described and measure the bend in the spar.
i have been writing about and using this for years.
Many things to consider. Increase of force? More focussed force? More radial? As, spar tilts; at that dynamic moment, what happens in the shifts in forces?
First flexxing is time i think maximum hinge strength is given, so more force, more focussed force, at this moment is very important by that model. If it doesn't stall, added pulls, pushes, cuts give more speed/ less power from the strength set at 'First Flexxing'; increasing the loading etc.
i use over the top on stuff 2-3' tall, to tumble more into rigging, i think giving stronger hinge to carry load longer and slower, before giving to rig is maximum. There might be an arguement that the power is not given to a tree hinge by this, because of no tumble/torque of distance; but msucling over a piece like this in slow motion on hinge, is more of a motion than static pull. i think we would more likely find the arched input effective then fer sure. i've turned this bend on the load/tree sideways, running the leg after the bend along the spar, or perpendicular to in years of rigging. It always seems, at each angle, short or tall, upside down, backward or to the side, that there is a differance in the bend; that is employable. The folks pulling the lines until something happens seem to agree, those watching the rigs, same. Loads seem to serve forward more focussed and sure; in addition to the pull of the line, the bend seems to want to dump it's excess load (and be straight) to reach minimal loading.
Nature wishes to run at minimal loading to task; as pattern/law. The Mayhem puzzle deal was to show the excess loading; that might wish to unload if it can. Any Bend of line giving multiplier, even ones back to themselves. In dragging logs i think i have noticed the farther apart the half hitch and timber hitch in killick (as example), the more 'stable' the drag, similar in rigging with 1/2 hitch preceding running bowline etc. Not for an increase in power; but smoother, more focussed power, that seems like it. As 1 aspect of the over the top pull, we have that leg of tense line pressing flat against the back 'spine' of the tree, pushing forward it seems. Like serving forward more focussed, under same power.
Any experiments done, must make sure their are no dutch's/ crossed cuts in the face; that would take efforts and load them into this disconnected compression, rather than in uncrossed cuts, forcing the connected hinge tension to be more. The effect best noticed if line coming over the top has as much purchase sweated out as possible, to increase energy store.
i too am a serious student; (when not clowning around... and even sometimes then..), the answer is elusive. i have followed the scent of some of these things to the correct door i think, so have some trust in that person-ally. Let us know what ya find!
Many things to consider. Increase of force? More focussed force? More radial? As, spar tilts; at that dynamic moment, what happens in the shifts in forces?
First flexxing is time i think maximum hinge strength is given, so more force, more focussed force, at this moment is very important by that model. If it doesn't stall, added pulls, pushes, cuts give more speed/ less power from the strength set at 'First Flexxing'; increasing the loading etc.
i use over the top on stuff 2-3' tall, to tumble more into rigging, i think giving stronger hinge to carry load longer and slower, before giving to rig is maximum. There might be an arguement that the power is not given to a tree hinge by this, because of no tumble/torque of distance; but msucling over a piece like this in slow motion on hinge, is more of a motion than static pull. i think we would more likely find the arched input effective then fer sure. i've turned this bend on the load/tree sideways, running the leg after the bend along the spar, or perpendicular to in years of rigging. It always seems, at each angle, short or tall, upside down, backward or to the side, that there is a differance in the bend; that is employable. The folks pulling the lines until something happens seem to agree, those watching the rigs, same. Loads seem to serve forward more focussed and sure; in addition to the pull of the line, the bend seems to want to dump it's excess load (and be straight) to reach minimal loading.
Nature wishes to run at minimal loading to task; as pattern/law. The Mayhem puzzle deal was to show the excess loading; that might wish to unload if it can. Any Bend of line giving multiplier, even ones back to themselves. In dragging logs i think i have noticed the farther apart the half hitch and timber hitch in killick (as example), the more 'stable' the drag, similar in rigging with 1/2 hitch preceding running bowline etc. Not for an increase in power; but smoother, more focussed power, that seems like it. As 1 aspect of the over the top pull, we have that leg of tense line pressing flat against the back 'spine' of the tree, pushing forward it seems. Like serving forward more focussed, under same power.
Any experiments done, must make sure their are no dutch's/ crossed cuts in the face; that would take efforts and load them into this disconnected compression, rather than in uncrossed cuts, forcing the connected hinge tension to be more. The effect best noticed if line coming over the top has as much purchase sweated out as possible, to increase energy store.
i too am a serious student; (when not clowning around... and even sometimes then..), the answer is elusive. i have followed the scent of some of these things to the correct door i think, so have some trust in that person-ally. Let us know what ya find!
NeTree
Addicted to ArboristSite
Ultimately, when it's time to git'r'done, I'm not dragging out the darn slide rule. Either you have an instinct for this stuff, or you don't.
Kinda like sizing up the trees for lean. How many loggers you see standing there studying the tree for hours?
Kinda like sizing up the trees for lean. How many loggers you see standing there studying the tree for hours?
There will be no more (intermediate?) "vector" with the laced-down-the-back setup than with the top-tied one. At least nothing that would be notable in practice. There are a couple factors your physicists need to bear in mind, namely that once the tree comes over-center the rope ain't doing a thing. This happens quite early in the scheme of things. The other thing is that the lower tie-in point of the back-laced method is itself part of the stem. I think what they're thinking is having the anchor being separate from the tree itself.Ekka said:
I cannot "open" your document, but would very much like to. I see it's a Microsoft Office file with an embedded Power Point something. If you're merely providing images, I'd like to suggest you use a <i>real</i> standard format, such as PNG if they're simply sketches, or JPG if they're annotated photos. Or if that's not possible for you for some reason, could you isolate the Power Point file instead of embedding it within another non-standard/closed-format entity.
Glen
Ekka Pic:
This is all i got in file.
Yeah, i embedded it, only ~8k!
i thnk MM original a lil big as .BMP
This is all i got in file.
Yeah, i embedded it, only ~8k!
i thnk MM original a lil big as .BMP
MasterBlaster
TreeHouse Elder
Glen, ya drive me nuts, but I wish I was as computer-savvy as you! 
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