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USnavy
Oct 29, 2013, 9:56 PM
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In light of the numerous topics regarding joining different-diameter ropes via an EDK, I decided to pull-test a piece of 11mm static and 6mm cordelette joined by an EDK. The cordelette was brand new but the static rope was used. I performed two types of tests: a standard EDK end-to-end destructive test and an EDK against an A2 stainless steel Fixe rap ring, which is the same ring used on millions of rap stations. For both tests, I pretensioned all four strands, I tied the EDK with the 6mm on bottom and I tied an overhand backup knot with the 6mm. I used a clove hitch to attach the test sample to a steel carabiner, which was attached to my testing platform.
Testing Layout
Figure one depicts the first test, an end-to-end pull-test.
Figure two shows the second test, which simulates a scenario in which the EDK is only acting as a stopper knot in the belay. In this photo I pulled on the 6mm cordelette, but I also conducted another test in which I pulled on the 11mm. The results were similar for both trials. The backup knot was did not tighten in either of the two tests.
Figure four indicates where the rope failed—at the clove hitch.
Results and Observations
The first test, an end-to-end static pull-test, resulted in the 6mm failing at the hydraulic cylinder with a peak load of 1,187lbf (5.28kN). The EDK knot did not roll; however, <em>the backup overhand knot was quite tight</em>, which implied that the backup knot was loaded. The second test, which simulated the climber using the EDK as a stopper knot against the belay station’s rings, resulted in the knot pulling through the Fixe ring at 800lbf (3.55kN). Worth noting is that I placed a carabiner in the Fixe ring to attach it to my load cell, which restricted the knot’s ability to pull through the ring. In a real-world scenario, the knot would have more room to pull through the ring.
Figure three:
Addendum
I tested the EDK with the 6mm on bottom and with the 6mm on top, both without a backup knot. In both tests, the 6mm broke at the hydraulic cylinder without the knot rolling (although it was close to rolling).
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majid_sabet
Oct 30, 2013, 5:14 PM
Post #2 of 12
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I am imaging myself simul-rapping with a partner, he is on 6 mm and I am on 11 mm static and rope is attached via EDK in to double chain loop on the anchor and bang, there we go , EDK pooped and my partner took 400 footer on the 6mm rope.
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rocknice2
Oct 31, 2013, 2:33 AM
Post #4 of 12
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Obviously one must de-core the 11mm rope to match the 6mm. That's the solution!
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majid_sabet
Oct 31, 2013, 5:17 AM
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acorneau wrote: majid_sabet wrote: I am imaging myself simul-rapping with a partner, he is on 6 mm and I am on 11 mm static and rope is attached via EDK in to double chain loop on the anchor and bang, there we go , EDK pooped and my partner took 400 footer on the 6mm rope.Why on earth would you do that?!?  If I absolutely, positively had to use this setup I would use a tandem rappel (i.e. two people on one rap device) with both ropes in the rap device.
well, you can technically rap on 2 mm cord if the other side is 10 mm and main knot is resting solid on the rap ring so testing this EDK knot against 11mm is waste of time .
I could properly use his harbor freight 10 ton press to change the bearing on my vw van.
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USnavy
Oct 31, 2013, 5:33 AM
Post #6 of 12
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majid_sabet wrote: I am imaging myself simul-rapping with a partner, he is on 6 mm and I am on 11 mm static and rope is attached via EDK in to double chain loop on the anchor and bang, there we go , EDK pooped and my partner took 400 footer on the 6mm rope.
(This post was edited by USnavy on Oct 31, 2013, 5:34 AM)
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USnavy
Oct 31, 2013, 5:36 AM
Post #7 of 12
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acorneau wrote: majid_sabet wrote: I am imaging myself simul-rapping with a partner, he is on 6 mm and I am on 11 mm static and rope is attached via EDK in to double chain loop on the anchor and bang, there we go , EDK pooped and my partner took 400 footer on the 6mm rope.If I absolutely, positively had to use this setup I would use a tandem rappel (i.e. two people on one rap device) with both ropes in the rap device.
(This post was edited by USnavy on Oct 31, 2013, 5:37 AM)
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acorneau
Oct 31, 2013, 11:54 AM
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USnavy wrote: acorneau wrote: If I absolutely, positively had to use this setup I would use a tandem rappel (i.e. two people on one rap device) with both ropes in the rap device. Why would you do that?
Sorry I was unclear.
What I meant to say is if I had to rap with two people at the same time (i.e. lightning, etc.) I would use a tandem rap and not one on each rope.
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majid_sabet
Nov 1, 2013, 2:22 AM
Post #9 of 12
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USnavy wrote: majid_sabet wrote: I am imaging myself simul-rapping with a partner, he is on 6 mm and I am on 11 mm static and rope is attached via EDK in to double chain loop on the anchor and bang, there we go , EDK pooped and my partner took 400 footer on the 6mm rope. More proof that you never actually climb. No one short of a complete moron would try to simul-rap on 6mm. Go ahead and rap on some 6mm. The EDK wont kill you, but Darwinism surely will.
so if no one raps or climb on 6 mm rope then doing a test on EDK serves no purpose unless, a big 900 lbs mama wants to pull the 6 mm rope on double rope rap system and out of his luck, the EDk becomes stuck in some crack and the hand pull forces of the 900 lbs mama causes the rope to break (at EDK) leaving mama on the wall and another job for rescuers .
(This post was edited by majid_sabet on Nov 1, 2013, 2:22 AM)
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majid_sabet
Nov 1, 2013, 2:33 AM
Post #10 of 12
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USnavy wrote: acorneau wrote: majid_sabet wrote: I am imaging myself simul-rapping with a partner, he is on 6 mm and I am on 11 mm static and rope is attached via EDK in to double chain loop on the anchor and bang, there we go , EDK pooped and my partner took 400 footer on the 6mm rope.If I absolutely, positively had to use this setup I would use a tandem rappel (i.e. two people on one rap device) with both ropes in the rap device. Why would you do that? This setup is extremely common among people that climb reasonably hard (AKA other than Majidoit). I have been using it for years. One person raps both strands, then the other person raps both strands. Kind of like how rapping is supposed to go, pre simul-rap era. One person at a time. None of this hauling ass to the ground with two people on one belay device, or simul-raping on the 6mm crap.
and you would rap with both strand on GG and similar devices ?
nice try
most climbers leave the knot to rest of the anchor ring (generally on the fat rope) and smaller diameter cord is to pull the big rope.
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dagibbs
Nov 1, 2013, 9:32 PM
Post #11 of 12
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majid_sabet wrote: I am imaging myself simul-rapping with a partner, he is on 6 mm and I am on 11 mm static and rope is attached via EDK in to double chain loop on the anchor and bang, there we go , EDK pooped and my partner took 400 footer on the 6mm rope.
Sure, you can imagine this. The real-world data, though, does not support the idea that what you are imagining would actually happen.
Actually, if we're going to imagine things, I think I'll imagine myself climbing 5.14. That's about as useful.
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USnavy
Nov 2, 2013, 2:45 AM
Post #12 of 12
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majid_sabet wrote: USnavy wrote: acorneau wrote: majid_sabet wrote: I am imaging myself simul-rapping with a partner, he is on 6 mm and I am on 11 mm static and rope is attached via EDK in to double chain loop on the anchor and bang, there we go , EDK pooped and my partner took 400 footer on the 6mm rope.If I absolutely, positively had to use this setup I would use a tandem rappel (i.e. two people on one rap device) with both ropes in the rap device. Why would you do that? This setup is extremely common among people that climb reasonably hard (AKA other than Majidoit). I have been using it for years. One person raps both strands, then the other person raps both strands. Kind of like how rapping is supposed to go, pre simul-rap era. One person at a time. None of this hauling ass to the ground with two people on one belay device, or simul-raping on the 6mm crap. and you would rap with both strand on GG and similar devices ? nice try most climbers leave the knot to rest of the anchor ring (generally on the fat rope) and smaller diameter cord is to pull the big rope.
(This post was edited by USnavy on Nov 2, 2013, 2:50 AM)
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