Dynamee Runner Failure

[Farrgo]

Failure Thread

[fenderfour]

This combined with JosephH's info might lead me away from the floss. I will be in teh market for 12mm slings soon.

[JosephH]

Just a note that Mammut sent me some 12mm Dynemma's to try out and I like them in terms of there is a bit more visual confidence that they might have a bit more longevity and ability to withstand abuse. But I also can't help but think that the weakness of the Dyneema is in the fibers themselves regardless of whether they are in an 8mm or 12mm configuration. That after x number of tight bends I'm guessing they are both shot. I also have no doubt that a 12mm is just as apt to cut under a girth hitch as the 8mm. I like these slings (especially the Mammut ones) and I'll be testing these after a couple of years, but I believe all smaller dyneema slings need to be treated as a short-lived consumable / disposable that need to be changed out after two years or so, after a wall or two, or after being subject to any harsh, suspect conditions or events. I'm swapping out all my 8mm this winter (some after 2 years, some after 3) and replacing some of them with 12mm slings.

[catbirdseat]

I just think that people need to realize that Spectra should be regarded rather like wire instead of like cord. Don't do anything with Spectra that you wouldn't do with wire. This modulus on this stuff is so low that it just doesn't tolerate sharp bends under load. Always use carabiners to join Spectra slings to other components of your system.

 

It is notable that we have not heard about sling failure when this stuff is catching lead falls. There is a reason for this. Most people use of carabiners.

[fenderfour]

I just think that people need to realize that Spectra should be regarded rather like wire instead of like cord. Don't do anything with Spectra that you wouldn't do with wire. This modulus on this stuff is so low that it just doesn't tolerate sharp bends under load. Always use carabiners to join Spectra slings to other components of your system.

 

It is notable that we have not heard about sling failure when this stuff is catching lead falls. There is a reason for this. Most people use of carabiners.

 

I think that we will hear of more sling failure over time as the Spectra deteriorates, but that's just my opinion.

 

The 12mm slings have more material so they should last longer.

 

I was just looking at my set of ratty 8mm Mammut slings last night. Time to replace.

[Cobra_Commander]

It is notable that we have not heard about sling failure when this stuff is catching lead falls. There is a reason for this. Most people use of carabiners.

 

WTF it's not notable when a product does what it is intended to do. It's rated to 22kN. What's it supposed to do?

[Farrgo]

WTF it's not notable when a product does what it is intended to do. It's rated to 22kN. What's it supposed to do?

 

What does that mean? Of course its supposed to catch falls. But its at least interesting that these things have yet to fail in a lead fall situation but have failed in others. Perhaps there is somthing in the nature of the material which weakens it in some situations as opposed to others.

[Cobra_Commander]

Spectra/Dyneema has a high tensile MBS but low MP and is subject to mechanical fatigue. This is not new information.

 

If this is not common knowledge that is a little frightening, I will agree.

[layton]

girth hitching two slings together is common practice, and the fact that this may cause one to break is not common knoweldge. it should be the manufacturer's responsibility to inform customers that their product won't do what it's supposed to.

[Cobra_Commander]

Definitely agree.

[catbirdseat]

girth hitching two slings together is common practice, and the fact that this may cause one to break is not common knoweldge. it should be the manufacturer's responsibility to inform customers that their product won't do what it's supposed to.

You have a good point. Manufacturers have not done enough to explain the proper use of these slings. It should not be surprising to anyone that when you go "high tech" that there will be more limitations on how the equipment can be used than the low tech alternative.

[fenderfour]

You have a good point. Manufacturers have not done enough to explain the proper use of these slings. It should not be surprising to anyone that when you go "high tech" that there will be more limitations on how the equipment can be used than the low tech alternative.

 

I'm getting tied hemp runners

[G-spotter]

i just clip a couple s together, sink the teeth of one into the next one's tail

[underworld]

girth hitching two slings together is common practice, and the fact that this may cause one to break is not common knoweldge. it should be the manufacturer's responsibility to inform customers that their product won't do what it's supposed to.

You have a good point. Manufacturers have not done enough to explain the proper use of these slings. It should not be surprising to anyone that when you go "high tech" that there will be more limitations on how the equipment can be used than the low tech alternative.

 

it's also common knowledge the knots in runners weakens them...as does girthhitching. it's up to the user as well to not only know this, but maybe also know WHY. sure the manufacturer puts the 22kn rating on it, but that is their tensile strength. only one ideal scenario. once the user realizes why girth hitching slings together weakens them, they might not girth hitch dyneema ones. they are skinny so the girthhitching will put even a more exagerated point load on the edges. i don't think it is the manufacturer's responsibility to make sure the user thinks of all this.

 

it's like saying that it is common practice for rope run over a rock. then asking: "why did this really sharp rock cut my rope?"

 

i guess i'm more of an advocate of know WHY something works rather than just remembering THAT something works. leave the burden on the user and the user will become smarter.

[catbirdseat]

Nowhere does it say not to girth hitch this material. Granted, this is not the same 7-8 mm material in question.

[Cobra_Commander]

Not a bad idea to say "this is a material that behaves differently than others, here's why." They sit right next to the regular runners. But yes, there should be some user responsibility.

 

Interesting that people are trying to shed weight with skinny runners. If that's what's preventing your send, well I guess you're climbing hard. I use a few myself, knowing they won't last forever and will melt easily.

 

The test could be repeated in a controlled setting. I may try a few older ones to check it out with a dynam. My guess is Mammut is on top of this stuff.

 

Que the rockclimbing.com elaborate contraptions for attaching two slings together...

[fenderfour]

Underworld Said: "it's also common knowledge the knots in runners weakens them...as does girthhitching."

 

This is very true, but you don't expect a knot to lower the strength that much. Typical strength losses due to knotting are 30%. The sling that failed went at 4 Kn at most. There's a difference of 11Kn between the expected loss of strength and the actual loss (in this case).

[dbb]

In March BD is coming out with some 10mm flat (not tubular) Dynex slings that are supposidly more abrasion resistant than the Dyneema slings. I wonder if they will retain their strength longer than the Dyneema ones. They certainly felt more "solid" and similar to the Wild Country skinny slings. Still, probably shouldn't girth hitch these either...

[ClimbingPanther]

It's widely thought that Dyneema and Spectra are the same thing, and in a way, they are, but in another way, they aren't.

 

What I mean is they're the same substance, but Dyneema fibers are spun thinner and they fray easier. Just a thought to keep in mind, especially when talking about wear from usage.

[ClimbingPanther]

At times the sling may have been stored in the same pack as a Bosch battery

 

Maybe this had nothing to do with it, but come on, why would you even take a chance?

[counterfeitfake]

When you buy something, you need to know what it's for and how to use it. It's important for the end user to be educated. Responsibility lies on both sides- one side has to provide the info and one side has to absorb it.

[underworld]

Underworld Said: "it's also common knowledge the knots in runners weakens them...as does girthhitching."

 

This is very true, but you don't expect a knot to lower the strength that much. Typical strength losses due to knotting are 30%. The sling that failed went at 4 Kn at most. There's a difference of 11Kn between the expected loss of strength and the actual loss (in this case).

 

girth hitching slings together is a whole different load scenario than knots. girth hitching a sling to a biner or an anchor is also different than g/h'ing slings together.

 

again...you can't just use the 30% as a blanket. you gotta look at what's going on w/ the details.

 

look at an extreme example: would you girthhitch a runner and a loop of piano wire together? well...when you start doing this with skinnier and skinnier slings you trend towards that scenario. it's no longer an axial strength issue.

[catbirdseat]

Don't forget that Mr. Sherman was rapelling on a single static line using a GriGri. The loads imparted using this method would be far in excess of what they would be using dynamic line and an ATC.

[underworld]

as usual...sounds like a summation of factors.

[Blake]

the sling here didn't really "wear out" or even "blow out" under a load.. it seems like being cut over a sharp edge (itself or another runner) is really what happened.