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Microfractures are a myth?
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squamishdirtbag


Jul 8, 2007, 12:00 PM
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Microfractures are a myth?
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So says this german dude I meet in yosemite, and this chick from the creek. I can't think of a reason to disagree, clearly fractures are real but so small they can't me seen?
What do you think paranoia or reality?


petsfed


Jul 8, 2007, 12:46 PM
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Re: [squamishdirtbag] Microfractures are a myth? [In reply to]
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Paranoia, at least in carabiners. The aluminum used in carabiners is much too soft to allow microfractures to develop. The rest of the crab would deform before a fracture of any size would appear.

The BD rule of thumb is that if has good gate action and isn't obviously thrashed, climb on. I'll leave it to you to dig up the study BD did with crabs found at the base of El Cap.


skinner


Jul 8, 2007, 12:56 PM
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Re: [squamishdirtbag] Microfractures are a myth? [In reply to]
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In reply to:
Myth #1: You should replace a dropped carabiner because of undetectable "Micro-Fractures".

This is the biggest myth we know of, and was probably created by unscrupulous salesmen to get you to buy more carabiners.

Truth: In a test by Steve Nagode, an engineer at the REI quality
assurance laboratory, 30 carabiner bodies (half ovals, half Ds) were each dropped six times onto a concrete floor from a height of 33 feet. Following the drops, their open-gate strength was measured and compared to 30 control samples from the same production batch and which had not been dropped. The statistical result showed no loss
of strength. Inspect any piece of dropped equipment carefully, checking for proper function. Cast metal products are most
vulnerable to damage, fractures and cracks. To my personal knowledge, this happened once to a gray cast Jumar Ascender in the 1970's. To my extensive knowledge: Drop forged carabiners (and similar gear) have not exhibited this problem.

Note: OEM Petzl says: 1mm of wear or gouge is serious enough wear or damage to require replacement.

from: onrope.com


microbarn


Jul 8, 2007, 1:26 PM
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Re: [squamishdirtbag] Microfractures are a myth? [In reply to]
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and possibly my thread that you just read?

SmileSmile

Microfractures are a real phenomena, and they occur in many if not all materials. The problem is when microfractures are self propagating. They self propagate because any point of high curvature in materials is a stress concentration. The end of a microfracture has high curvature. If the material can yield sufficiently to disperse the concentration at the tip of the crack, the microfracture will not self propagate.

I haven't seen a definitive answer about materials used in climbing and their self propagation of microfractures.

In any case, with materials experiencing many loading cycles microfractures could be an issue. However, the fracture will grow to a size you can see prior to total failure. With regular visual inspection, microfractures aren't something to worry about. You should catch the crack prior to total failure.

Many leader falls certainly have sufficient forces and conditions to start a microfracture. However, many people use the same equipment for years. This either points to materials that limit microfracture self propagation or insufficient loading cycles in climbing applications. Until we have better data, we can't answer the questions much better.

So, while I can't rule out microfracture fears, we can rest a little easier. When there are many unexplained failures of equipment, then we should reevaluate our concern over microfractures.

FYI: Airplanes coming in for standard inspections are often given a passing grade with known cracking of important weight bearing parts. They only repair or replace the parts after the cracks propagate "too far" http://www.google.com/...e=UTF-8&oe=UTF-8.


cortisol


Jul 9, 2007, 11:14 AM
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And remember, when in doubt, send your questionable carabiners to Microbarn for inspection.


midwestishell


Jul 9, 2007, 1:55 PM
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Its nice to see that some tests have been done on this instead of relying on personal paranoia or machismo.

Just another thought, what about cams? A buddy of mine dropped a cam several months back. It had a few major dings to it but wasn't deformed or anything along those lines. The action of the lobes also seemed fine. Do you think that the same holds true for the materials in a cam or do the moving parts and such add another degree of uncertainty to the device?

Thanks.
Th


yorb


Jul 9, 2007, 2:44 PM
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Re: [midwestishell] Microfractures are a myth? [In reply to]
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Aren't Carabiners and Cams far more likely to have any significant damage from forces generated in a fall rather than being dropped? There is so much more stress placed on equipment that is loaded by a falling climber than from being dropped on a rock??? Not that I'm any where near an expert, but it just makes sense. (not that everything having to do with physics readily makes sense)


knieveltech


Jul 9, 2007, 2:53 PM
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Re: [yorb] Microfractures are a myth? [In reply to]
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yorb wrote:
Aren't Carabiners and Cams far more likely to have any significant damage from forces generated in a fall rather than being dropped? There is so much more stress placed on equipment that is loaded by a falling climber than from being dropped on a rock??? Not that I'm any where near an expert, but it just makes sense. (not that everything having to do with physics readily makes sense)

Maybe? If you drop gear on a rock there's no rope acting as a giant shock absorber. Also, it's possible that forces would be applied to the gear along lines never intended to encounter such forces. Random speculation on my part. Given there are moving parts involved, I might consider retiring a cam after a long fal, especially if it got dinged up in odd placesl, whereas I'd cheerfully climb on a #11 nut that had been dropped from low earth orbit (assuming the cable still looked good). YMMV.


greenketch


Jul 9, 2007, 2:54 PM
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Re: [yorb] Microfractures are a myth? [In reply to]
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It is true that the forces are higher in catching a fall. The point is that aluminum (the base material that most climbing gear is made of) is not a subject to micro fracture. It does not matter what the use is. That is also why the comment about airplanes passing inspections with known cracks is relavent.


yorb


Jul 9, 2007, 3:02 PM
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Re: [greenketch] Microfractures are a myth? [In reply to]
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Does anyone have any links from reputable sources that pretty well dispel this myth. I.E. manufacturers. My school's outdoor program pretty much tells everyone here that micro-fractures occur in aluminum and if you drop something over 15 feet it should be retired. In fact a lot of people who go through the program here come out as "steel" guys, they don't trust it if its not steel. I have searched on RC.com to find good outside links and on google, but I haven't found any good sources... Saying, "I read this on rockclimbing.com" doesn't cut it, if you can imagine that.


boku


Jul 9, 2007, 5:14 PM
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Re: [yorb] Microfractures are a myth? [In reply to]
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yorb wrote:
Does anyone have any links from reputable sources that pretty well dispel this myth. I.E. manufacturers...

Personally, I consider the REI QA engineer cited previously by Skinner "reputable."

A while back I dropped a friend's C4 #4 from near the top of the first pitch of Selaginella. My bad. I bought him a new one and he let me keep the dropped one. Then I filed and sanded out the few dings, pull-tested it to half its rating, and now it's on my rack. Not exactly win-win, but fair enough.


greenketch


Jul 9, 2007, 5:44 PM
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I would also list Black Diamond amoung reputable sorces. Their testing can be found on their site I believe.


saxfiend


Jul 9, 2007, 8:12 PM
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Re: [yorb] Microfractures are a myth? [In reply to]
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yorb wrote:
In fact a lot of people who go through the program here come out as "steel" guys, they don't trust it if its not steel.
I can just visualize you and your buddies, well-trained by your school's expert instructors, racked up for a multi-pitch trad climb with 20-30 assorted steel biners on your harness. Hope your gear loops are reinforced.

JL


yorb


Jul 9, 2007, 8:42 PM
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Re: [saxfiend] Microfractures are a myth? [In reply to]
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The courses here are not for personal use, they follow the ACCT (Association for Challenge Course Technology) standards which are primarily for ropes courses and commercial situations. They are conservative so as to avoid potential law suits. Most of the people who go through the courses are not climbers; but, as a result they have misconceptions about aluminum equipment. I don't have a problem with the commercial standards, just the resultant impression placed on people who don't know any better.

Links?? I've looked on BD's site and found some stuff, but I never found the article about the dropped biners at Yosemite. I'm looking for primary sources, not other people copying what a primary source said without a link.

Thanks though


(This post was edited by yorb on Jul 9, 2007, 8:43 PM)


summerprophet


Jul 9, 2007, 8:48 PM
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Most of the cases of microfractures occur on objects that have repeated high stress cycles (car suspension springs) or have been exposed to extreme temperatures (welding).

My mountain bike was full of them.... sadly they turned into "macrofractures" then "megafractures".

Anyone wanna buy a "lightly used" Rocky Mountain?


robbovius


Jul 10, 2007, 9:30 AM
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summerprophet wrote:
Most of the cases of microfractures occur on objects that have repeated high stress cycles (car suspension springs) or have been exposed to extreme temperatures (welding).

?

How is everyone missing the examples of the crankshaft, connecting rods, and pistons in internal combustion engines. this in the realm where microfractures are a real concern. carabiners and cams? not so much.


boku


Jul 10, 2007, 10:13 AM
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Re: [yorb] Microfractures are a myth? [In reply to]
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yorb wrote:
...Links?? I've looked on BD's site and found some stuff, but I never found the article about the dropped biners at Yosemite. I'm looking for primary sources, not other people copying what a primary source said without a link.

I was referring to this link:

skinner wrote:
...from: onrope.com

BD != REI

Bob K.


(This post was edited by boku on Jul 10, 2007, 10:18 AM)


pylonhead


Jul 10, 2007, 11:05 AM
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boku wrote:
yorb wrote:
...Links?? I've looked on BD's site and found some stuff, but I never found the article about the dropped biners at Yosemite. I'm looking for primary sources, not other people copying what a primary source said without a link.

I was referring to this link:

skinner wrote:
...from: onrope.com

BD != REI

Bob K.

onrope != REI either. Anyone have a link to the actual study? I did some googling, but couldn't find it.


shimanilami


Jul 10, 2007, 11:06 AM
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greenketch wrote:
It is true that the forces are higher in catching a fall.

That can't be right. The shock force when a piece of gear strikes rock (e.g. talus at the base of a climb) is incredibly high.

Just consider removing a pin. You can jump up and down on the thing all day long - even with a static sling - and it won't budge, but a few taps with a hammer can knock it right out.

The impact force is much higher when there is no elasticity in the system.


boku


Jul 10, 2007, 11:30 AM
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Re: [pylonhead] Microfractures are a myth? [In reply to]
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"pylonhead wrote:
onrope != REI either. Anyone have a link to the actual study? I did some googling, but couldn't find it.

If I really cared a lot, I'd just email Mr. Nagode.


dalguard


Jul 10, 2007, 1:22 PM
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Re: [boku] Microfractures are a myth? [In reply to]
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I've been told you should try R&I # 81 (Sep 97) .


yorb


Jul 10, 2007, 1:56 PM
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Thanks for patronizing me, I know BD and REI are two seperate entities. I have often heard people talk about a BD test with dropped carabiners picked up from Yosemite, but never a link to the primary source. Also Onrope is not a primary source. I also tried to find REI's test results, but couldn't. What flies is documents straight from the source that actually did the test. I.E. Petzl, BD, REI, etc...


(This post was edited by yorb on Jul 10, 2007, 1:59 PM)


boku


Jul 10, 2007, 2:06 PM
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yorb wrote:
Thanks for patronizing me...

No problem, glad to help.

Bob K.


dalguard


Jul 10, 2007, 8:39 PM
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Page 117. The article quotes both the REI test and Chris Harmston from BD. It was written by Clyde Soles. You want to hear it from the source, find a copy of the magazine.


yorb


Jul 10, 2007, 8:43 PM
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thank you, i'll look it up when I get a chance.

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