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  1. W

    Petzl Grillion

    I don't understand the difference between the Zillon and ZigZag apart from the way they are marketed and the extra holes. Could one climb exclusively on the Zillon? (Maybe with a rope wrench for SRT.)
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    Petzl guideline on choked carabiner anchor for spar work

    The reason for the caution is given above the image.
  3. W

    Petzl guideline on choked carabiner anchor for spar work

    But they removed the cinched carabiner configuration entirely, suggesting that despite the warning this is better? Am I misinterpreting this?
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    Petzl guideline on choked carabiner anchor for spar work

    Petzl has replaced the original content with this: With good reason or to maximize profit? I leave the reader to decide.
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    Forces on a cinched carabiner

    That's pretty much it. Coefficient of friction rope-carabiner and rope-bollard are both adjustable, but I am using 0.22 and 0.3 respectively based on available papers. Varying the bollard friction coefficient strongly affects the configurations that are stable. That's a bit "above my pay...
  6. W

    Forces on a cinched carabiner

    I am not familiar with this method. Would you explain this? I know that I can keep force on the long axis of the carabiner by clipping it into a knot tied on the back strand, but that also removes the cinching force and makes the attachment remotely irretrievable.
  7. W

    Forces on a cinched carabiner

    I seek peer review, and I do not like to take and not give so I am looking for a way to contribute. I created the simulation for my own education but I thought sharing the results might be one way to do that. I don't mean that with hubris as though you need my help. I merely want to offer...
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    I like big butt(ress) and I cannot lie

    I recognize that one. The poor tree is so beaten up from all the selfie takers.
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    Forces on a cinched carabiner

    Hey y'all, I don't bite.
  10. W

    What’s your favourite lanyard set up

    What is the solution for a hitch that holds in both directions, but doesn't bind? Mirrored hitches with the attachment in between?
  11. W

    Shizll rope slider wanted

    For thinner rope and cord the Kong Slyde might have a use. I came up with this a couple of years ago for 10.7mm rope and 6.5mm cord. Tying the cord through the plate makes it easy to get the length just right but it limits cord diameter to about 7mm for two strands. I suppose thicker cord...
  12. W

    Forces on a cinched carabiner

    Thanks!? :LOL: When there is sufficient friction around the spar the rope going to the green point is effectively fixed, but if the friction coefficient is reduced the simulation exhibits the reduction in configurations that can achieve equilibrium. If you wrap a slick post and try to double...
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    Forces on a cinched carabiner

    The How NOT 2 video on cinched carabiners made me interested in the forces involved and I decided to make a simulation. Fair warning, I am not an engineer. I hope we can reason together if I got it right from the geometry I used to set it up. The general trends in the result are probably...
  14. W

    Sticht Hitch

    Which diameter?
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    Sticht Hitch

    Thanks moss. These are subtle but very important details that aren't in The Tree Climber's Companion.
  16. W

    Sticht Hitch

    It seems to be holding today in the same configuration. The hitch cord is starting to fuzz up just a bit. Could that be all that was needed? I have not needed to break in cord for a classic Prusik to hold but this is obviously rather different.
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    Rope Breakage Research

    A common view is that if it passes the UIAA drop test it has adequate margin. A minimum five 1.78 fall factor drops with a rigid 80 kg mass and a rigid belay, in comparatively quick succession, is an extremely harsh test. A carabiner with a somewhat smaller yet smooth radius than the 5mm test...
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    Rope Breakage Research

    That is unrelated to breaking strength, it just means that the impact force of a given fall will be higher. A dynamic rope with an ideal breaking strength of 14 kN will also break below that with a knot in the system, or when bent over an edge.
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    Rope Breakage Research

    Knotted strength is less, and it didn't break at the knot so that checks out. The part that broke is out of frame so we cannot see if it broke at another knot, a bend over a lip, or a different form of termination.
  20. W

    Sticht Hitch

    @Brocky I thought I had a working hitch, as above but without the scrap wood, but I tried it "low and slow" today and had a failure: when I used a foot ascender the hitch would not catch. I could stretch the hitch by hand and it would grab and hold, but left alone it would slide. I tightened...

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