Old Dogbones and Wire Draw Strength Test
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Geir was nice enough to break some old stuff for me. |
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Love it when Geir starts testing stuff. Really gives me confidence in things I used to worry about and a realistic view on some other things. |
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These testing threads are some of the BEST! |
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I've got a few old draws/short open slings he can break. How do I contact him? |
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Gunkiemike wrote:I've got a few old draws/short open slings he can break. How do I contact him?Search for Geir on here. |
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Search for Geir on here. |
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Very cool 20 kN thanks for offering. My rig is best suited for static pull tests. |
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This is awesome! |
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We do that all the time All Killer No Filler. Everything is batch tested in house. Check out this video of us testing our beam anchors. http://www.youtube.com/watch?v=9L2ENA4mX1Q |
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We gotta gather all these together in one post. I sent Geir some 'biners that were up to 33 yrs old and he found some would not bust at 5,000lbs. Great pics and nice to see how our gear is WAAAAY stronger than we ever think a fall could create. |
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We would be happy to contribute, we break old anchors all the time, daily even. |
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Is the prize the piece of broken gear to hand from their Subaru mirror? |
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Is there any differnce in the results for a slow pull until failure versus a fast "shock load" like a climbing fall would create. I'm picturing the sort of tests that I believe that they put dynamic ropes through. |
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I'm no engineer and I don't even play one on TV but I think its the peak load generated during the fall and how that matches up with the maximum load of the piece of gear that matter. Especially in the case of something like a permadraw where the "quality" of the placement *shouldn't* matter. |
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John Husky wrote:Is there any differnce in the results for a slow pull until failure versus a fast "shock load" like a climbing fall would create. I'm picturing the sort of tests that I believe that they put dynamic ropes through.In the case of hard goods, I dont know, but I suspect the answer is no. If the answer was yes, I suspect the UIAA probably would not be doing static pull tests to certify, biners, cams, ect. But they would be more qualified to answer that question. In the case of ropes, I believe the answer is yes, to some extent. I was able to get a few samples of an old rope to rip at 1300lbf with heavy sheath damage at 1000lbf. I tested other samples from the same in FF2 scenarios and they held multiple FF2 falls without incident. In the case of slings, the answer is most certainly yes, at least with UHMWPE material. A FF2 drop on a Dyneema sling with a static weight has been proven to result in a failure strength below the sling's rated capability. I believe this is largely due to the heat produced by the fall and the very low strength reduction temperature of UHMWPE material. FF2 falls on frozen Dyneema slings seem to show improved performance.DMM has some nice testing data on dynamic loading scenarios for Dyneema slings posted on their site. |
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John Husky wrote:Is there any differnce in the results for a slow pull until failure versus a fast "shock load" like a climbing fall would create. I'm picturing the sort of tests that I believe that they put dynamic ropes through.There is a difference but the basic concept of the safety chain is that one has a dynamic rope and all other components are merely connectors to either the climber or the rock. The dynamic rope is an impact attenuator and reduces the rate of strain (the speed at which the load is applied to the connectors) to a level which is considered slow by engineering and materials standards. Drop tests onto equipment such as karabiners without an impact attenuator are in general meaningless, a disservice to the climbing community and unfair to the manufacturers unless the results are presented with a far greater knowledge of engineering than is usually displayed on the internet. |
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20 kN wrote: In the case of slings, the answer is most certainly yes, at least with UHMWPE material. A FF2 drop on a Dyneema sling with a static weight has been proven to result in a failure strength below the sling's rated capability. I believe this is largely due to the heat produced by the fall and the very low strength reduction temperature of UHMWPE material.Can you direct me to a test where the peak load in the Dyneema sling in a drop test was measured and shown to be lower than the static strength? Yea, I've seen the DMM test, but don't recall any load numbers. I default to believing that a drop test produces a spike in load to many tens of thousands of lbf. Analogous to folks who can break a biner with a funkness device. |
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Gunkiemike wrote: Can you direct me to a test where the peak load in the Dyneema sling in a drop test was measured and shown to be lower than the static strength? Yea, I've seen the DMM test, but don't recall any load numbers. I default to believing that a drop test produces a spike in load to many tens of thousands of lbf. Analogous to folks who can break a biner with a funkness device.Sure, right here. dmmclimbing.com/knowledge/k… Cue up to the 4:35 mark in the video. The guy specifically says that dynamic drops produce a lower breaking strength than static tests due to the low melting point of Dyneema. Also, when you say " I default to believing that a drop test produces a spike in load to many tens of thousands of lbf." what type of drop test are you talking about? Just any dynamic loading scenario? Or specifically drop tests on static material? |