Broken TIP

levi r said:
I'm glad that you avoided injury, Neill!

2 person test never made sense to me. Would it have broken with one climber not bouncing? Cycles to failure? There was a climber in a comp here years ago who got a questionable tip. 2 person bounce, it held. Then broke while he was ascending afterwards.
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wood often does not break immediately when it's stressed... Have you eer noticed that undercutting a heavy horizontal limb with a handsaw seems to break out faster and easier than it would with a chainsaw... it's not the undercut that changes things... it's the top cut. Making a top cut with the chainsaw blows through to fibers at each level before they have time to split... the top cut with a handsaw is so slow that the stressed fibers have time to fracture before the next stroke.
 
Daniel said:
wood often does not break immediately when it's stressed... Have you eer noticed that undercutting a heavy horizontal limb with a handsaw seems to break out faster and easier than it would with a chainsaw... it's not the undercut that changes things... it's the top cut. Making a top cut with the chainsaw blows through to fibers at each level before they have time to split... the top cut with a handsaw is so slow that the stressed fibers have time to fracture before the next stroke.
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Width of kerf also plays a significant role, that and speed of cut. It’s been way too long since I’ve played with a straight handsaw vs curved.
 
levi r said:
I'm glad that you avoided injury, Neill!

2 person test never made sense to me. Would it have broken with one climber not bouncing? Cycles to failure? There was a climber in a comp here years ago who got a questionable tip. 2 person bounce, it held. Then broke while he was ascending afterwards.
Click to expand...
I think you would agree that trees can absorb some wind gusts, their flexibility allows them to move and respond, displacing the energy from a gust or a bounce, even if it is a two person bounce. Why a two person load? It will put enough load on the anchor so that it may be observed and provide a safety margin from any likely load from a climber rope walking up the rope. When I have measured loads while moving smoothly up the rope, I generate about 120% of my static load. (A climber humping the tree may have a different experience ;-) Doing 3 or 4 or even more times the load may do damage to the branch and thus defeat the purpose of the test.
Does that make sense?
 
Bouncy no bueno - Devil's advocate- I've climbed where bouncy but I could see the down rope was clear and over a sound tip and the basal rope was deflecting some inconsequential stuff sideways. You'd think that when you drop your throw bag it gets the clear path and you tie it to the basal end of your SRT line so the basal side is always clear - but sometimes you thread the throw line and pull the basal rope end from the "cube" end. I recall some trepidation about tying another throw bag to the cube end and trying to pull it up through the snarl and also expect it to come back through the snarl, thus just let it be a side deflector.

edit - I got my logic backwards. drop bag, tie basal end, basal end straight up over tip back down over side deflectors, tie to trunk, so it's the default. avoiding cube end of throw line w/second bag up/ down through snarl still stands.

edit 2 - 20% of body weight increase at the climber for climb thrusts is about right, except for Mark Chisholm's SRT tip x2 loading proof video where he ain't stealth and probably times his leg thrusts into the bounce frequency of the rope! Also his tip was a pulley... IIRC typical non-hero descent stop is about 25% increase on the down rope, stealth probably 10%. This was incidental to hitch/RW tuning data.
 
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Richard Mumford-yoyoman said:
I think you would agree that trees can absorb some wind gusts, their flexibility allows them to move and respond, displacing the energy from a gust or a bounce, even if it is a two person bounce. Why a two person load? It will put enough load on the anchor so that it may be observed and provide a safety margin from any likely load from a climber rope walking up the rope. When I have measured loads while moving smoothly up the rope, I generate about 120% of my static load. (A climber humping the tree may have a different experience ;-) Doing 3 or 4 or even more times the load may do damage to the branch and thus defeat the purpose of the test.
Does that make sense?
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No. I'd never do a 2 person bounce on a tip I wanted to climb on.
 
levi r said:
No. I'd never do a 2 person bounce on a tip I wanted to climb on.
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Just to be clear, I'm not advocating to do a two person bounce. I'm advocating that no bounce be done in a test environment, bouncing is ineffective for a test. I'm trying to explain that a tree would absorb the bounce and therefore Invalidate the test.
 
levi r said:
No. I'd never do a 2 person bounce on a tip I wanted to climb on.
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So I guess we would agree to disagree. Personally , if I think putting a double load on my anchor is going to damage it, I'm not going to be using it as a single point of attachment. It would not make sense to me to have five thousand pound ratings on everything in my bag and place it on an anchor I think could fail at 400.
 
Just a reminder 23 kN is high as a start point for the cycles to failure curve, so you never operate near break strength during service life (textiles), Falling arrest load spike is secondary issue, dealt with by high start point and restricted service life.
 
levi r said:
Exactly, so why test it? Just get a tie in that you know won't break. Why push it?
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This is when the real world and on paper collide.....
The Internet has a way of painting with a broad brush and makes it seem so simple...but in reality it's the end of a long day or your throw line skills are bad, or the only bombproof tie Ins are 20-30 feet below the areas you need to access to complete the work order.
Some people have luxury that others don't and there's a million reasons why we push the limits and go up on anchors we do not like....
Depends on what day of the week it is, what time it is, the task ahead, fatigue, skill, patience.
 
If you feel like you don't have the luxury of saying no to a certain task or tree that sounds like a fucked situation and I'd recommend finding a new one asap.
 
Mowerr said:
This is when the real world and on paper collide.....
The Internet has a way of painting with a broad brush and makes it seem so simple...but in reality it's the end of a long day or your throw line skills are bad, or the only bombproof tie Ins are 20-30 feet below the areas you need to access to complete the work order.
Some people have luxury that others don't and there's a million reasons why we push the limits and go up on anchors we do not like....
Depends on what day of the week it is, what time it is, the task ahead, fatigue, skill, patience.
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I agree. There have been many times I was very confident I got a bomber tip. Just two weeks ago I shot right through a union of a topped western red cedar. Looked bomber from the ground and in someways it was. Except for I was over a little twig above the union. Surprised the thing held and it was just a climbing inspection. If it was work, and it broke loose it could have been a damaging situation.
I’ve had those bust loose when reaching out for a cut with a chainsaw. Falling towards the saw just a foot is still way too much of a fall.
For shits and giggles this can be an argument for one handing, but I won’t go there
 
You thought that you had a bomber tie in though. That's the difference to me. Would you climb on something questionable just because you were too tired, not good at throw ball and trying to fulfill the work order?
 
levi r said:
You thought that you had a bomber tie in though. That's the difference to me. Would you climb on something questionable just because you were too tired, not good at throw ball and trying to fulfill the work order?
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the short answer here is yes I would
1. I’m an idiot
2. I’d test that anchor

But you have me feeling introspective. You are not wrong, taking a safety first approach. Or maybe better put, just being conscious of the real life consequences that are going to boomerang around after too many dice rolls. And for what? Another $20 .
But this is a weird profession. Why in the world does anyone do tree work
 
The weird thing about testing your anchor is…
If it did suddenly break, then I will fall down and be underneath a branch that is probably plummeting to the earth. I guess that’s marginally better than falling out of the tree
 
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