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esander4


Nov 30, 2010, 9:09 PM
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Gear testing soon, suggestions wanted
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My brother has a mechanical engineering project coming up and he wants to do some tests on climbing equipment for it. I'll be helping him with it, so my question is, is there anything specific that anyone would like to see done? Anything that may have been hard to do due to money or lack of equipment? He has full access to testing equipment (specifically what, I don't know, but I can always ask him if anyone has specific questions about that) and a 400 dollar grant from the university to buy test gear with. The tests will be taking place over the course of the winter, but he needs input quickly to buy the gear to test.


TarheelJD


Nov 30, 2010, 9:25 PM
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I would like to see what the breaking strength of cordelette tied with a triple fisherman's knot in a quad with a biner around three of the four strands between overhand limiter knots spaced 10-12 inches. Also, overhand knots where the quad would normally be attached to bolts. If you had a steel member you could actually put those two ends 1-2 ft apart to simulate a typical arrangement. Do that with 8mm and 7mm nylon cord, maybe spectra or 1inch webbing too. I have a feeling it might exceed whatever load cells he is using but I am interested to see what the breaking force is and the point of failure.

I've seen a lot of tests of those materials and knot strength tests but can't recall seeing a quad test. On that note, if anyone has seen one, please pass it along.


jt512


Nov 30, 2010, 9:33 PM
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I'd like to see a comparison of the breaking strengths of light-weight I-beam carabiners with carabiners made from conventional stock when loaded over an edge. The rated strengths of these biners are similar, but I've always been suspicious of how the newer biners would fare if loaded over an edge.

Jay


patto


Nov 30, 2010, 11:31 PM
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jt512 wrote:
I'd like to see a comparison of the breaking strengths of light-weight I-beam carabiners with carabiners made from conventional stock when loaded over an edge. The rated strengths of these biners are similar, but I've always been suspicious of how the newer biners would fare if loaded over an edge.

Jay

If they are bent across the short axis then they should be stronger than convential stock carabiners. If they are bent across the long axis then they will be weaker.


moose_droppings


Nov 30, 2010, 11:50 PM
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esander4 wrote:
My brother has a mechanical engineering project coming up and he wants to do some tests on climbing equipment for it. I'll be helping him with it, so my question is, is there anything specific that anyone would like to see done? Anything that may have been hard to do due to money or lack of equipment? He has full access to testing equipment (specifically what, I don't know, but I can always ask him if anyone has specific questions about that) and a 400 dollar grant from the university to buy test gear with. The tests will be taking place over the course of the winter, but he needs input quickly to buy the gear to test.

How about cutting one loop (ear) on a Double Figure Eight (Bunny Ears) and pull test the other loop to failure. Would like to see if the loop will pull thru (as many speculate) or if the loop will break. You could use a couple different widths of dynamic climbing rope around 9mm-11mm.

I'm sure you already know to dress and set any knots you guys decide to test.


esander4


Dec 1, 2010, 12:15 AM
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Just out of curiosity, what would be the practical application of that? Meaning, at what point would just one loop get cut but not the other? I only use DFE for belay anchor so I can't see it getting cut in that situation, but you may use it for way more than I do. But DFE with one cut loop would be an interesting test. Do you think getting multiple brands of rope along with different sizes would be good, or should we stick with a uniform brand of rope? Don't know if that would make a difference


esander4


Dec 1, 2010, 12:25 AM
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jt512 wrote:
I'd like to see a comparison of the breaking strengths of light-weight I-beam carabiners with carabiners made from conventional stock when loaded over an edge. The rated strengths of these biners are similar, but I've always been suspicious of how the newer biners would fare if loaded over an edge.

Jay

Would DMM Big Boa and Petzl Attache be suitable gear for the I-Beam vs Conventional Carabiner test?


jt512


Dec 1, 2010, 1:03 AM
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esander4 wrote:
jt512 wrote:
I'd like to see a comparison of the breaking strengths of light-weight I-beam carabiners with carabiners made from conventional stock when loaded over an edge. The rated strengths of these biners are similar, but I've always been suspicious of how the newer biners would fare if loaded over an edge.

Jay

Would DMM Big Boa and Petzl Attache be suitable gear for the I-Beam vs Conventional Carabiner test?

No. The I-beam construction whose over-an-edge breaking strength I'm suspicious of is like that of the Petzl Attache 3D. In principle, comparing it with a conventional Petzl Attache would be ideal, since the two biners have similar rated strengths and designs, except for the aluminum stock used. However, I'd rather see non-locking biners used for the test (I think), since I think that they might be more susceptible to breaking when loaded over an edge than locking biners.

This page has pictures of both the conventional and "3D" versions of the Petzl Attache.

Jay


patto


Dec 1, 2010, 1:55 AM
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An I beam, by its very nature, is much weaker when bent along the plane that is parallel to the long part of the I.


bill413


Dec 1, 2010, 5:53 AM
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I've always been curious about the effect of pairing two locking biners (opposite & opposed) on their strength. I'm curious if it's weaker than two non-lockers, or one locker & one non-locker. The hypothesis is that the locking mechanism applies sideways loading to the gate because of pressure from the other biner.


bill123


Dec 1, 2010, 6:09 AM
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I'd be interested to see testing of different knots in strands of dyneema slings. In other words, if you needed to build an anchor using v-threads and your only option was to cut and retie dyneema slings, what knot would be the strongest? I've heard a lot of speculation about this, but have seen no hard data.


MS1


Dec 1, 2010, 7:58 AM
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bill123 wrote:
I'd be interested to see testing of different knots in strands of dyneema slings. In other words, if you needed to build an anchor using v-threads and your only option was to cut and retie dyneema slings, what knot would be the strongest? I've heard a lot of speculation about this, but have seen no hard data.

+1.


esander4


Dec 1, 2010, 8:50 AM
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bill413 wrote:
I've always been curious about the effect of pairing two locking biners (opposite & opposed) on their strength. I'm curious if it's weaker than two non-lockers, or one locker & one non-locker. The hypothesis is that the locking mechanism applies sideways loading to the gate because of pressure from the other biner.

It's been to my knowledge that if enough weight were to be put on 2 opposite and opposed lockers then the screwgate part of the carabiner would just slip past the spine of the other carabiner. Meaning take 2 opposite and opposed biners in front of you, and move one to the left about an inch and that's how I think they would end up under enough force. But now you've struck my curiosity. Cheap and easy testing, you got it.


esander4


Dec 1, 2010, 8:55 AM
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bill123 wrote:
I'd be interested to see testing of different knots in strands of dyneema slings. In other words, if you needed to build an anchor using v-threads and your only option was to cut and retie dyneema slings, what knot would be the strongest? I've heard a lot of speculation about this, but have seen no hard data.

Do you have specific knots you want to see done other than the general figure eight, overhand, waterknot, etc.?


bill123


Dec 1, 2010, 9:06 AM
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esander4 wrote:
bill123 wrote:
I'd be interested to see testing of different knots in strands of dyneema slings. In other words, if you needed to build an anchor using v-threads and your only option was to cut and retie dyneema slings, what knot would be the strongest? I've heard a lot of speculation about this, but have seen no hard data.

Do you have specific knots you want to see done other than the general figure eight, overhand, waterknot, etc.?

Since many of the thinner dyneema slings are almost round in cross section, I would add a triple fisherman's. If I were doing the testing, I'd leave out the figure eight since it is generally accepted that a figure eight capsizes under a relatively small load.


moose_droppings


Dec 1, 2010, 9:48 AM
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esander4 wrote:
Just out of curiosity, what would be the practical application of that? Meaning, at what point would just one loop get cut but not the other? I only use DFE for belay anchor so I can't see it getting cut in that situation, but you may use it for way more than I do. But DFE with one cut loop would be an interesting test. Do you think getting multiple brands of rope along with different sizes would be good, or should we stick with a uniform brand of rope? Don't know if that would make a difference

It's a good knot for when you need to adjust the size of the two different loops easily.

I can't really see one side getting cut without the other either, but it's a common argument that people use to to explain why bunny ears are not safe to use.

Using a couple different sizes for testing would calm other fears that the one ear may remain intact depending on the size of the rope used. It would be a more thorough and wider excepted test.

It would be nice to put this myth to bed.
Thanks for considering.

Thanks.


esander4


Dec 1, 2010, 10:12 AM
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moose_droppings wrote:
esander4 wrote:
Just out of curiosity, what would be the practical application of that? Meaning, at what point would just one loop get cut but not the other? I only use DFE for belay anchor so I can't see it getting cut in that situation, but you may use it for way more than I do. But DFE with one cut loop would be an interesting test. Do you think getting multiple brands of rope along with different sizes would be good, or should we stick with a uniform brand of rope? Don't know if that would make a difference

It's a good knot for when you need to adjust the size of the two different loops easily.

I can't really see one side getting cut without the other either, but it's a common argument that people use to to explain why bunny ears are not safe to use.

Using a couple different sizes for testing would calm other fears that the one ear may remain intact depending on the size of the rope used. It would be a more thorough and wider excepted test.

It would be nice to put this myth to bed.
Thanks for considering.

Thanks.

Sounds good


hafilax


Dec 1, 2010, 11:14 AM
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Can you do dynamic pull tests or drop tests?


boymeetsrock


Dec 1, 2010, 11:33 AM
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bill123 wrote:
In reply to:
esander4 wrote:
bill123 wrote:
I'd be interested to see testing of different knots in strands of dyneema slings. In other words, if you needed to build an anchor using v-threads and your only option was to cut and retie dyneema slings, what knot would be the strongest? I've heard a lot of speculation about this, but have seen no hard data.

Do you have specific knots you want to see done other than the general figure eight, overhand, waterknot, etc.?

Since many of the thinner dyneema slings are almost round in cross section, I would add a triple fisherman's. If I were doing the testing, I'd leave out the figure eight since it is generally accepted that a figure eight capsizes under a relatively small load.

How about a flemish bend instead.


(This post was edited by boymeetsrock on Dec 1, 2010, 11:36 AM)


bill123


Dec 1, 2010, 11:51 AM
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Flemish Bend instead of figure eight? Good idea!


dynosore


Dec 1, 2010, 12:13 PM
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How about building a fixture that is basically 2 parallel plates with interchangeable faces and adjustable angles. Maybe have a c channel to capture the stone block so you can just drop it in. Hopes that makes sense. Vary the angles between the plates from parallel to 30 flaring in several increments. Test pullout strength of some of the fancy new cams and see if they really hold better.


shoo


Dec 1, 2010, 1:02 PM
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dynosore wrote:
How about building a fixture that is basically 2 parallel plates with interchangeable faces and adjustable angles. Maybe have a c channel to capture the stone block so you can just drop it in. Hopes that makes sense. Vary the angles between the plates from parallel to 30 flaring in several increments. Test pullout strength of some of the fancy new cams and see if they really hold better.

+1


esander4


Dec 1, 2010, 1:02 PM
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dynosore wrote:
How about building a fixture that is basically 2 parallel plates with interchangeable faces and adjustable angles. Maybe have a c channel to capture the stone block so you can just drop it in. Hopes that makes sense. Vary the angles between the plates from parallel to 30 flaring in several increments. Test pullout strength of some of the fancy new cams and see if they really hold better.

That one would be a good idea, the money may be an issue though. We would probably only be able to test a max of 2 cams, maybe only 1, unless we completely disregarded everyone else's ideas. I'll just have to see how everything balances out, once all the ideas are in (PS everyone, I need all of the ideas by next Friday, we're hoping to buy gear shortly after that an test as soon as we have it)


esander4


Dec 1, 2010, 1:05 PM
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I'll be setting up a poll with everyone's ideas on Friday the 10th. You can vote on them and we'll choose from what the most people want


Partner philbox
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Dec 5, 2010, 12:06 PM
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moose_droppings wrote:
esander4 wrote:
My brother has a mechanical engineering project coming up and he wants to do some tests on climbing equipment for it. I'll be helping him with it, so my question is, is there anything specific that anyone would like to see done? Anything that may have been hard to do due to money or lack of equipment? He has full access to testing equipment (specifically what, I don't know, but I can always ask him if anyone has specific questions about that) and a 400 dollar grant from the university to buy test gear with. The tests will be taking place over the course of the winter, but he needs input quickly to buy the gear to test.

How about cutting one loop (ear) on a Double Figure Eight (Bunny Ears) and pull test the other loop to failure. Would like to see if the loop will pull thru (as many speculate) or if the loop will break. You could use a couple different widths of dynamic climbing rope around 9mm-11mm.

I'm sure you already know to dress and set any knots you guys decide to test.

I recently participated in a testing session where we pulled a bunny ears to destruction. We then took one ear off the test rig and tested again. No difference. The load strand where it enters the knot is always the strand that breaks. The load strand cinches the rest of the knot such that no parts of the knot can move except that the load strand moves around the various strands within the knot causing friction which eventually causes the load strand to fail.

I still have the evidence in my garage. The unfixed ear will NOT pull through the knot. Ever. End of story.

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