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TarHeelEMT
Nov 5, 2010, 10:10 PM
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Has anyone tested the degree to which blowing the pockets on various daisy chains compromises the strength of the strength of the daisy itself? I've heard this as dogma for years, but I've never seen numbers. Intuitively it makes sense, but I'm curious as to the extent of the compromise.
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jt512
Nov 6, 2010, 2:45 AM
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TarHeelEMT wrote: Has anyone tested the degree to which blowing the pockets on various daisy chains compromises the strength of the strength of the daisy itself? I've heard this as dogma for years, but I've never seen numbers. Intuitively it makes sense, but I'm curious as to the extent of the compromise.
When the pockets blow, the damage is not confined to the stitching. The sling itself is damaged. In controlled tests, daisies have completely failed when the pocket failed.
Jay
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redlude97
Nov 6, 2010, 3:16 AM
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three words: micro shock loading
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Express
Nov 6, 2010, 7:51 AM
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redlude97 wrote: three words: micro shock loading
I think the term you're looking for is "cascade failure"
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meanandugly
Nov 6, 2010, 11:50 AM
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How does this compare with macro shock loading?
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onceahardman
Nov 6, 2010, 1:04 PM
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jt512 wrote: TarHeelEMT wrote: Has anyone tested the degree to which blowing the pockets on various daisy chains compromises the strength of the strength of the daisy itself? I've heard this as dogma for years, but I've never seen numbers. Intuitively it makes sense, but I'm curious as to the extent of the compromise. When the pockets blow, the damage is not confined to the stitching. The sling itself is damaged. In controlled tests, daisies have completely failed when the pocket failed. Jay
To be perfectly clear, I agree with you. From the standpoint of pure intellectual curiousity, I'm wondering about these controlled tests. Are they available anywhere, to look at?
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TarHeelEMT
Nov 6, 2010, 1:21 PM
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onceahardman wrote: jt512 wrote: TarHeelEMT wrote: Has anyone tested the degree to which blowing the pockets on various daisy chains compromises the strength of the strength of the daisy itself? I've heard this as dogma for years, but I've never seen numbers. Intuitively it makes sense, but I'm curious as to the extent of the compromise. When the pockets blow, the damage is not confined to the stitching. The sling itself is damaged. In controlled tests, daisies have completely failed when the pocket failed. Jay To be perfectly clear, I agree with you. From the standpoint of pure intellectual curiousity, I'm wondering about these controlled tests. Are they available anywhere, to look at?
That's what I'd like to see as well. I'm curious as to the extent and predictability of the damage, whether it varies with dyneema vs nylon, across different brands, etc..
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dan2see
Nov 6, 2010, 1:24 PM
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Use regular draws.
or...
Get a Screamer.
or...
Jump off the cliff with nothing.
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TarHeelEMT
Nov 6, 2010, 1:39 PM
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dan2see wrote: Use regular draws. or... Get a Screamer. or... Jump off the cliff with nothing.
A screamer certainly would be an interesting (albeit useless) way to attach my aiders to my harness.
I have no interest in using them in lieu of a screamer or as my main attachment to the anchor. I'm an aid climber who often wonders just what blowing a pocket while I'm fified into it would do to the integrity of the whole thing.
This is the lab, and I have to believe that somebody here has tested this. I'd do it myself, but I lack a force gauge.
(This post was edited by TarHeelEMT on Nov 6, 2010, 1:55 PM)
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dan2see
Nov 6, 2010, 2:55 PM
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TarHeelEMT wrote: ...A screamer certainly would be an interesting (albeit useless) way to attach my aiders to my harness. I have no interest in using them in lieu of a screamer or as my main attachment to the anchor. I'm an aid climber who often wonders just what blowing a pocket while I'm fified into it would do to the integrity of the whole thing. This is the lab, and I have to believe that somebody here has tested this. I'd do it myself, but I lack a force gauge.
Aiders?
OK let's back up here: In the OP, you wrote, "blow a pocket on a daisy", but you didn't write "aiders".
Some folks will anchor themselves with a daisy, so I guessed that you meant you were worried about blowing a loop on the daisy, while belaying. I've done aid a couple of times, so I didn't recognize that was your topic.
But as far as I can see, you won't "blow a pocket while I'm fified into it ". Unless your aider is so ratty and worn that you should have thrown it away a long time ago.
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TarHeelEMT
Nov 6, 2010, 5:11 PM
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dan2see wrote: TarHeelEMT wrote: ...A screamer certainly would be an interesting (albeit useless) way to attach my aiders to my harness. I have no interest in using them in lieu of a screamer or as my main attachment to the anchor. I'm an aid climber who often wonders just what blowing a pocket while I'm fified into it would do to the integrity of the whole thing. This is the lab, and I have to believe that somebody here has tested this. I'd do it myself, but I lack a force gauge. Aiders? OK let's back up here: In the OP, you wrote, "blow a pocket on a daisy", but you didn't write "aiders". Some folks will anchor themselves with a daisy, so I guessed that you meant you were worried about blowing a loop on the daisy, while belaying. I've done aid a couple of times, so I didn't recognize that was your topic. But as far as I can see, you won't "blow a pocket while I'm fified into it ". Unless your aider is so ratty and worn that you should have thrown it away a long time ago.
Of course it wouldn't blow while just fified, but for curiosity's sake I sometimes wonder about it while I'm hooked in. There are, though, other situations where one could conceivably blow a pocket while aiding, and I'd like to see the lab data if anyone has it.
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jt512
Nov 6, 2010, 5:24 PM
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onceahardman wrote: jt512 wrote: TarHeelEMT wrote: Has anyone tested the degree to which blowing the pockets on various daisy chains compromises the strength of the strength of the daisy itself? I've heard this as dogma for years, but I've never seen numbers. Intuitively it makes sense, but I'm curious as to the extent of the compromise. When the pockets blow, the damage is not confined to the stitching. The sling itself is damaged. In controlled tests, daisies have completely failed when the pocket failed. Jay To be perfectly clear, I agree with you. From the standpoint of pure intellectual curiousity, I'm wondering about these controlled tests. Are they available anywhere, to look at?
To the best of my recollection, the tests I'm thinking of were conducted more than 10 years ago, and I think I first read about them on rec.climbing; so your best bet for tracking down the details of the tests might be to search the rec.climbing archives using groups.google.com. I have a vague recollection that they were reported by then-QC manager of Black Diamond Chris Harmston.
Jay
(This post was edited by jt512 on Nov 6, 2010, 6:14 PM)
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TarHeelEMT
Nov 6, 2010, 6:04 PM
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Thanks jay. I'll try to track those down.
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bearbreeder
Nov 8, 2010, 6:37 AM
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http://www.caves.org/section/vertical/nh/53/RiggingForRescue-DaisyChains-2005.pdf
they dropped and dropped and dropped static loads on daisies ... nylon ones worked fine
blew out bar tacks like it was supposed to but the sling held
i too would like to see actual published test results showing that a blown pocket on a daisy will cause the failure of the sling itself ... basically a 2kn fall causes the failure of a 20kn rated sling
if this was the case then i suspect many companies would no longer sell daisies ... now sewn screamers for that matter
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ptlong2
Nov 8, 2010, 4:37 PM
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http://www.fishproducts.com/tech/bolts.html
In reply to: Re: Belay anchors: why not use daisy chains? Author: Chris Harmston Email: chrish@bdel.com Date: 1997/12/16 Forums: rec.climbing Daisy's are weaker than runners because, as the pockets rip out, damage to the webbing occurs at the pocket tacks. In static testing the pockets rip out until you are in the standard runner configuration. The web breaks at the damaged area of one of the pocket tacks. In factor 2 falls with 185 lbs of steel I have seen some break outright without popping all the pockets! I have also seen them hold factor 2 falls and pop all pockets. Dynamic loading is not the same as the slow pull we use for batch testing and rating. Runner materials do not stretch like your ropes does. Use your rope for your primary anchor and use the daisy as a backup and as the adjustability. I have heard reports of daisy's breaking in factor 2 aid falls. The samples I have seen that broke in the field were fairly well worn. Daisy's get worn quite quickly and their strength degrades accordingly. Use your rope as the primary anchor! Chris Harmston (chrish@bdel.com). Quality Assurance Manager. Materials Engineer BS, ME. Black Diamond Equipment Ltd. 2084 East 3900 South, SLC, UT 84124 phone: 801-278-5552
(This post was edited by ptlong2 on Nov 8, 2010, 5:29 PM)
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jt512
Nov 8, 2010, 4:56 PM
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bearbreeder wrote: http://www.caves.org/section/vertical/nh/53/RiggingForRescue-DaisyChains-2005.pdf they dropped and dropped and dropped static loads on daisies ... nylon ones worked fine blew out bar tacks like it was supposed to but the sling held
Oh, so now that's a "feature," is it?
Jay
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majid_sabet
Nov 8, 2010, 5:08 PM
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TarHeelEMT wrote: Has anyone tested the degree to which blowing the pockets on various daisy chains compromises the strength of the strength of the daisy itself? I've heard this as dogma for years, but I've never seen numbers. Intuitively it makes sense, but I'm curious as to the extent of the compromise.
Mike Gibbs of Rigging for Rescue did test several daisy (including PAS) on FF2 with 100 KG and most failed around FF 1.25 or less. I have posted several images of the test in here so do a search and check them out. Actually, I examined few of them closely and since then, I switched to purcell prussic.
(This post was edited by majid_sabet on Nov 8, 2010, 5:10 PM)
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bearbreeder
Nov 8, 2010, 6:12 PM
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no one answered the question of why sewn screamers are "safe"
when a sewn screamers rips ... the same thing happens ... why doesnt the stitching damage the sling then?
just some post from 1997 ... perhaps someone should ask the current BC QA lab about this ...
camp did the best simulation with a harness in the system and a dyneema daisy ... the sling didnt self destruct
http://www.climber.co.uk/categories/articleitem.asp?item=583
id really like something more current that says that a 2kn fall will cause the failure of a 22kn daisy
when i now have 2 links which show test where that hasnt been an issue on nylon daisies at the minimum
majid ... did the dyneema daisies failed because dyneema doesnt stretch, not because the daisy pockets cause the failure ... a dyneema sling would have failed as well
the nylon ones held
as stated the most realistic test done by camp with a harness showed no issue
http://www.caves.org/section/vertical/nh/53/RiggingForRescue-DaisyChains-2005.pdf
(This post was edited by bearbreeder on Nov 8, 2010, 6:16 PM)
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redlude97
Nov 8, 2010, 6:24 PM
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For one thing, the stitch on a screamer is oriented in such a way that it fails in a linear "series" manner as it is designed for that purpose, while daisy stitches are oriented across the webbing and close to the edges of the webbing which has a different mode of failure that can weaken the webbing more than the screamer.
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jt512
Nov 8, 2010, 6:27 PM
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bearbreeder wrote: no one answered the question of why sewn screamers are "safe" when a sewn screamers rips ... the same thing happens ... why doesnt the stitching damage the sling then?
Obviously because Screamers use a weaker stitch.
Jay
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bearbreeder
Nov 8, 2010, 6:31 PM
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redlude97 wrote: For one thing, the stitch on a screamer is oriented in such a way that it fails in a linear "series" manner as it is designed for that purpose, while daisy stitches are oriented across the webbing and close to the edges of the webbing which has a different mode of failure that can weaken the webbing more than the screamer.
do you have any tested results or proof that it compromises the sling?
i think its time to send ask the actual QA departments of the various daisy manufacturers
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jt512
Nov 8, 2010, 6:33 PM
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bearbreeder wrote: redlude97 wrote: For one thing, the stitch on a screamer is oriented in such a way that it fails in a linear "series" manner as it is designed for that purpose, while daisy stitches are oriented across the webbing and close to the edges of the webbing which has a different mode of failure that can weaken the webbing more than the screamer. do you have any tested results or proof that it compromises the sling?
The proof was posted up-thread by ptlong2.
Jay
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bearbreeder
Nov 8, 2010, 6:39 PM
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jt512 wrote: The proof was posted up-thread by ptlong2. Jay
no jay thats something from 17 years ago ... and i posted links to 2 tests where nylon daisies and a camp daisy held fine
im getting tired of this constant run around ...
im emailing all the daisy makers i kind find about internet "experts" telling us all these daisies will fail
theyll be the ones who can best answer the questions
i really dont care one way or another ... i just want the REAL facts
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ptlong2
Nov 8, 2010, 6:44 PM
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These tests done by Mike Gibbs don't directly address the question posed by the OP. Except for a few special cases, it appears that the mass was situated on the end of the daisies in these drops, not on an intermediate pocket.
In reply to: i too would like to see actual published test results showing that a blown pocket on a daisy will cause the failure of the sling itself ... basically a 2kn fall causes the failure of a 20kn rated sling
That's not quite what is being suggested. Rather, it's that a more severe fall will cause the sling to break before blowing all of the pockets (what Harmston reported).
In reply to: if this was the case then i suspect many companies would no longer sell daisies ... now sewn screamers for that matter
Daisies are neither made nor marketed to be misused in the manner you are suggesting. As an extreme example, Metolius sells a daisy that is rated at 1.3 kN (300 lbf) -- not the pockets (there are none), but it's full strength.
Screamers are specifically designed and tested for the stitches to rip while maintaining runner integrity. MAYBE a daisy would do this... but at least one respected engineer at Black Diamond found otherwise.
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jt512
Nov 8, 2010, 6:48 PM
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bearbreeder wrote: jt512 wrote: The proof was posted up-thread by ptlong2. Jay no jay thats something from 17 years ago ... and i posted links to 2 tests where nylon daisies and a camp daisy held fine im getting tired of this constant run around ...
Actually, you're creating the run-around.
In reply to: im emailing all the daisy makers i kind find about internet "experts" telling us all these daisies will fail
One daisy manufacturer, Black Diamond, has already given their opinion. The fact that the opinion was stated in 1997 is irrelevant, unless BD has strengthened their daisies—which, if they have, they've been quiet about.
Jay
(This post was edited by jt512 on Nov 8, 2010, 7:14 PM)
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