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JimT
climber
Munich
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Jun 14, 2010 - 04:06am PT
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I did some pull tests on guide plates (related to using them for roped-soloing):-
When you overload guide plates they do funny things.
The first is that the trapped rope escapes sideways from under the tensioned rope and gets trapped between the tensioned rope and the side of the slot.This is very difficult to free off and you have to dismantle everything and twist the locking krab brutally to release the rope.
Apply yet more load and the trapped rope where it crosses the tensioned rope goes down through the slot with a bang. At this point the holding power drops off considerably but not catastrophically, though pretty near!
Easy to releasse, just unclip the krab when unweighted.
ATC Guide. 8.2mm Edelrid, new,treated. First fail mode 2.05kN. Max fail load 4.06kN. Residual load 1.2kN
ATC Guide. 9mm Edelrid, used, non treated. First fail mode 2.96kN. Max fail load 5.58kN. Residual load 1.6kN
Reverso³. 8.2mm Edelrid, new,treated. First fail mode 1.6kN. Max fail load 2.38kN. Residual load 0.7kN
Reverso³. 9mm Edelrid, used, non treated. First fail mode 2.25kN. Max fail load 3.60kN. Residual load 0.9kN
Reverso³. 10.2 Mammut, used, non treated. First fail mode 3.68kN. Stopped test at 7kN as I didn´t have the tester guards on and things start breaking over these sort of loads!
All with Petzl Attache 12mm round profile karabiner.
I´ve some more results somewhere but can´t lay my hands on them at the moment, anyway I guess the picture is clear enough!
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HMS
Trad climber
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Jun 14, 2010 - 04:39am PT
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In reply to Gost: ' the TRE Sirius solved all the problems. Even on skinny ropes on an overhanging rappel, you can simply let go'
Unfortunately the Tre is not that good. On overhanging rappel with brand-new 7.5 mm twin-ropes and on overhanging rappel with new 8.0 mm double ropes, it simply did NOT lock completely. Wet ropes made things a lot worse and made rappelling quite scary.
I normally use the original Magic Plate by New Alp (same type of device as the Kong GiGi or Camp Ovo) with 7.5 mm twinropes when climbing multipitch rockclimbs. I love the simplicity of the design, BUT even a device as simple as the Plate has failed on one occasion (in auto-block mode belaying a second). The rope going down to the climber was squeezed past the other: i.e. normally the rope leading to climber blocks bottom rope, but this time the rope squeezed past the rope it was supposed to block. As it happened to just one of the ropes, the autoblock function(of the other rope) was not impaired. But it shows that belaying/climbing with skinny ropes is dangerous.
Ergo: belay devices versus skinny ropes = DANGER.
On a belay-device the slot through which the rope goes has to be large enough for a furry 10.2 mm rope. But it has to be small enough to avoid a new 7.5 mm to squueze past itself. It seems this is simply not possible to achieve. Manufacturers of belay devices should stop selling devices for a wide range of rope diameters. They should also inform about the dangers of belaying with skinny (dry-treated) ropes. Often the belayer gets the blame for dropping a climber, but often its the device at fault.
Read more on belay devices and friction here: http://www.bolt-products.com/Glue-inBoltDesign.htm
edit: See previous post.
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Degaine
climber
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Jun 14, 2010 - 06:40am PT
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Hello HMS,
Just as a preface to my upcoming question / comment :
*I’ve used the Kong Gigi, the New’Alp plaquette, all three reverso models as well as the ATC guide.
*I have more experience than some, less than others, would never claim to be smarter than anyone or to have THE answer.
So here goes. You wrote:
BUT even a device as simple as the Plate has failed on one occasion (in auto-block mode belaying a second). The rope going down to the climber was squeezed past the other: i.e. normally the rope leading to climber blocks bottom rope, but this time the rope squeezed past the rope it was supposed to block.
I just don’t get how this can happen. Normally when a second hangs his end of the rope weights the carabiner in place, which in turn pinches the belay hand end of the rope (hope I’m clear). Here’s a photo:
http://www.decathlon.co.uk/products-pictures/gd-asset_11458904.jpg
Even if the two sides of the rope nestle up side by side, I still don’t see how the rope going down to the climber would not pinch of the other side of the rope when weighting the carabiner.
Please don’t take this as an aggressive or defensive post, just trying to better understand.
Cheers.
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JimT
climber
Munich
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Jun 14, 2010 - 08:20am PT
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As I said above, the upper loaded rope forces it´s way down past the braking strand and in the end the positions are reversed so that the loaded rope is underneath and the braking rope on top (and obviously not doing a lot of braking). The thinner guide plates tend to go straight to this reversed position whereas the deeper belay devices have an intermediate stage when the two ropes cross each other inside the device.
You can see this happening easily if you put a length of 5/6mm cord in a belay device in guide mode and give it a pull.
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sieczk
Mountain climber
Reno, NV
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Jun 14, 2010 - 09:52am PT
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dr spock wrote:
the hole they give you to stick a biner in as a lever to unbrake is too small for a biner!
A Petzl non-locking biner from a quickdraw fits perfectly into that hole (designed that way on purpose).
Wrong, and wrong. The hole is meant to accept the 'tooth' of a carabineer http://www.youtube.com/watch?v=93YDB1jj21s @ 4:19.
The system, when used correctly, is idiot proof. Seeing as how you claim to be a guide and will never admit to doing anything wrong, I will tell you publicly that you did mess up somewhere in utilizing the auto-block function of the reverso. This is what may have happened:
-The orientation of the hanging device was twisting the ropes as they passed through the friction slots. This is easy to do if you're belaying off the shelf of an anchor and the reverso is cantered in a sideways manner. The twisting of the ropes will make thin ones "flip" inside the slot, especially when icy/wet.
-You tried to release the follower by simply passing the rope back through the feeder. Congratulations on defeating all safety systems and principles associated with the device in one fell swoop.
-You put the rope bights in backwards. The weight of the load-bearing rope is meant to seize the belay by jamming it into the friction slots. Try it in reverse and you'll see that there is NO friction without the aforementioned rope play.
-The orientation of the belay device prevented the load rope to fully compress the belay end. Upside-down, free hanging anchors will do this. Don't build an anchor in a roof.
There are more ways to eff this up out there but I am quickly running out of test subjects here to find them all. Regardless, when used correctly, the Reverso3 is a great tool and is not to be chastised because of user error.
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slobmonster
Trad climber
OAK (nee NH)
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Jun 14, 2010 - 12:05pm PT
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Even if the two sides of the rope nestle up side by side, I still don’t see how the rope going down to the climber would not pinch of the other side of the rope when weighting the carabiner.
I can back up the OP. Although I have not witnessed this happen "on its own," there was a not uncommon guiding trick (probably frowned on, now) that we'd occasionally with the Gi-Gi: you can "pop" the ropes by each other ON PURPOSE with a deft twist of the blocking carabiner, facilitating a lowering setup.
Please note that the wire loop (a la Reverso, Guide ATC, et al.) SHOULD effectively prevent this from happening... as the blocking carabiner needs to make a 180 in order to pop.
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J. Werlin
Social climber
Cedaredge, CO
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Jun 14, 2010 - 12:07pm PT
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Thanks for the tech info JimT. Question: are the failure loads you describe consistent with the forces generated by the fall of a second?
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Degaine
climber
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Jun 14, 2010 - 12:08pm PT
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I wrote:
A Petzl non-locking biner from a quickdraw fits perfectly into that hole (designed that way on purpose).
In response sieczk wrote:
Wrong, and wrong. The hole is meant to accept the 'tooth' of a carabineer http://www.youtube.com/watch?v=93YDB1jj21s @ 4:19.
Actually, I'm right, I've done it for realsies. But if you don't believe me, just call Petzl.
You are, however, correct that shows how any biner will work, but that particular hole in the R3 was designed so that certain Petzl biners fit perfectly.
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Degaine
climber
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Jun 14, 2010 - 12:12pm PT
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JimT wrote:
As I said above, the upper loaded rope forces it´s way down past the braking strand and in the end the positions are reversed so that the loaded rope is underneath and the braking rope on top (and obviously not doing a lot of braking).
My apologies, JimT, I just simply don't understand your explanation. The biner in the photo is in the way (and serving its purpose) - it blocks one strand from going below the other(and with two ropes in the device I do not see how it would be possible).
I'll admit that I perhaps do not understand what you mean by "the upper loaded rope forces its way down past the braking strand".
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slobmonster
Trad climber
OAK (nee NH)
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Jun 14, 2010 - 12:15pm PT
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Degaine: the (blocking) carabiner has to twist ~180° for the scenario to occur as described.
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Ghost
climber
A long way from where I started
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Jun 14, 2010 - 12:25pm PT
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HMS -- I should probably have been a little more careful with my language. That is, the TRE solved all the problems for me. My skinny ropes are Petzl Dragonflies which, at 8.2mm are slightly thicker than the ropes you've been using. And although I've put on a couple of pounds in my old age, I'm still not very heavy and my partner is even lighter. So, in our case at least, the TRE does lock up when released on a free-hanging rappel.
I certainly don't dispute that you, with your skinnier ropes found that it didn't.
And I fully agree with you that "belay devices vs. skinny ropes = Danger." Or maybe "= potential danger."
The TRE also functions beautifully as a belay device both for belaying the leader or second, as long as you're using thin ropes. But despite being wonderful to use with skinny ropes, the TRE absolutely SUCKS DEAD RATS when used with fat ropes.
But it's all moot, because the TRE is dead.
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Degaine
climber
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Jun 14, 2010 - 01:00pm PT
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slobmonster wrote:
Degaine: the (blocking) carabiner has to twist ~180° for the scenario to occur as described.
That's impossible if climbing with two ropes (meaning two ropes of a double rope or a twin rope setup).
Thanks for the response.
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slobmonster
Trad climber
OAK (nee NH)
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Jun 14, 2010 - 02:18pm PT
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That's impossible if climbing with two ropes (meaning two ropes of a double rope or a twin rope setup).
Absolutely.
But from my reading, the OP was using a skinny rope SINGLY.
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JimT
climber
Munich
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Jun 14, 2010 - 03:11pm PT
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The karabiner doesn´t `have´to twist at all, you could weld the sucker in place! I can´t see how I can explain it any more simply or clearly, the loaded rope squeezes the unloaded rope (which is underneath) out of the slot. The karabiner doesn´t move. You can have one or two ropes, it changes nothing.
I´ve watched this happen about 40 times on the test rig and like I said, get a piece of thin cord and try it for yourself.
As regards the forces from falling seconding they could be virtually anything but up to 5kN is realistically feasible. There is an American website out there with some tests on this which I´ll see if I can find a link to.
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J. Werlin
Social climber
Cedaredge, CO
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Jun 14, 2010 - 03:59pm PT
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Thanks JimT.
Can someone help me draw a general conclusion to all this data?
Is the bottom line that using a Reverso3 in autoblock mode (1 rope or 2, regardless of diameter) unsafe with hands off?
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et
climber
Bozeman, MT
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Topic Author's Reply - Jun 14, 2010 - 11:46pm PT
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Jim T. ~
That is great info - thanks for posting. It is extremely easy to generate those failing forces if the second falls with a little slack in the line.
Check out this video put out by BD. http://vimeo.com/10584731
BD does note, however, that you should never take your hand off the brake. Given the power of video though, they are sending mixed messages.
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Dr.Sprock
Boulder climber
Sprocketville
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Jun 15, 2010 - 12:09am PT
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hey Jim, if i pay for a reverso 3, will you fail test the big loop?
i would really like to know how many pounds that skinny alloy can take.
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rgold
Trad climber
Poughkeepsie, NY
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Jun 15, 2010 - 01:35am PT
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One should perhaps add as a footnote to Jim's tests that a guide plate enabled multitasking belayer, for whom managing the belay momentarily takes second place to spreading the pate de fois gras on his baguette, is considerably more likely to let some slack accumulate and so create a situation in which the second takes a leader fall, thereby "overloading" the "hands-off" device with consequences likely to spoil everyone's lunch.
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Trad
Trad climber
northern CA
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Jun 15, 2010 - 01:50am PT
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J. Werling wrote:
Can someone help me draw a general conclusion to all this data?
Is the bottom line that using a Reverso3 in autoblock mode (1 rope or 2, regardless of diameter) unsafe with hands off?
I too would like to hear a "bottom line". Anyone? So far my conclusions are:
(a) when used according to manufacturer's specs, the Reverso 3 is safe,
(b) if you use thinner ropes, spread pate de fois gras while belaying, or otherwise tweak the system based on unfounded assumptions, the Reverso3 (and other similarly-designed devices) may fail, and
(c) there are complexities associated with hand-free belay devices so know what you're doing.
Am I on the right track here? I don't mind being told I'm wrong, but if I'm wrong I just want to know why.
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Dr.Sprock
Boulder climber
Sprocketville
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Jun 15, 2010 - 02:34am PT
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they look cool and work great,
just keep the brake grooves on the un loaded rope and every thing is beautiful, in its own way, like a ...fading fast.......goodnight.
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