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theartboy
May 13, 2005, 12:56 PM
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First, I want to say this is not a troll. I don't believe in the microfracture myths in climbing gear (yes, airplanes do experience it, but they go through significantly more loading cycles). I have read the Chris Hartman (BD tester) report on testing dropped gear (and every other thing I can find).
My question is whether anyone has actually had gear break during a fall? I read about the guy who loaded the cam sideways in the Gunks and it broke. Bad alloy, bad design, or just bad use? Anyone else break a cam during a fall (and please don't bring up the red alien story that the OP never responded while the folks at CCH did reply)? If this really were an issue, I believe we would read more articles in Accidents in North American Mountianeering about people cratering because they used booty or dropped gear that failed.
Now comes another question. Has anyone had a hex or stopper break? Not the cable (or sling), but the metal itself broke during a fall? Most people (myself included) have used their #11 as a hammer. It might scratch the hex, but compromise its safety? Unless it has a visible sign of damage, I think metal climbing gear can be used. Recently someone posted that your main belay biner will (not might) fail after two year from bodyweight loading alone. How many times a day, everyday, do you have to fall to cause that failure? I think my body would give out first.
What worries me more is aged slings. Instead of all the worry about the possibility of a microfracture, I would be more concerned about the integrity of the sling on old or booty gear.
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wlderdude
May 13, 2005, 3:03 PM
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If you want to do some quick research on why aluminum can break from body weight cycles, look up the term "endurance limit." Specifically aluminum doesn't have one. Basically it means that no matter how low the loading is, aluminum will eventually fatigue and break if given enough cycles. Steel has what's called an endurance limit meaning that if the loading stays below a certain level, no number of cycles will fatigue it (this can fall apart if cracks are present).
Now you have the advantage of the gear you use for climbing being specifically designed for climbing. The manufacturers of gear specify that soft goods are designed for 5 years of normal usage and hard goods for 10. Thus, after what a manufacturer would consider 10 years of appropriate use, you could consider retiring your hard goods.
Note that the equations people use to calculate things like cycles to failure are experimentally based. You can rest assured that the CE certified gear companies have done plenty of cyclical loading tests. Some kid who sits down with a machine design book and uses the tables in the back to calculate the number of cycles of a half inch aluminum rod with a 90 degree bend to fatigue should concern you. These do not supersede actual testing of actual carabiners made with tailored tempered aluminum alloys.
As for gear failing, sure it happens. Usu sally when people misuse it. But to be honest, I am just as afraid the the rack and pinion in my car will strip out in the middle of a 60 mph turn on the freeway and or something else will cause me to loose steering and I'll crash in a fiery ball of carnage. Hey, I am only trusting a couple of bolts.
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sarcat
May 13, 2005, 3:46 PM
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So I can use the BD cams I dropped on my garage floor last year and be safe? I was going bankrupt from replacing every piece I drop 'cause I'm "butter fingers".
:deadhorse:
Still no one has answered what the smily has against the horse's junk.
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j_ung
May 13, 2005, 3:52 PM
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^^
Issues involving the smily's father date back to its early childhood.
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paulraphael
May 13, 2005, 4:57 PM
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http://web.mit.edu/afs/.athena/course/21/21w794/model/Okal_Marianne_62 2.pdf
this is some research done at MIT on carabiners. looks like a good study, although it assumes that a hard fall is capable of loading a biner with over 20kn, which seems bizarre.
carabiners are a good piece to study because empirically, they seem like the one piece of hardware that does actually break from time to time (although evidence, including this study, suggests that it's not from fatigue)
short of it is, yes, aluminum parts can fail from fatigue, but under the low stresses (repeated bodyweight cycles) encountered in most of climbing, the number of stress cycles required to reach failure is orders of magnitude higher than what's likely to be encountered.
there are so many more likely ways to get offed, including different kinds of equipment failur, that I wouldn't even consider the possibility of hexes and nuts fatiguing. Your carabiners might break--but if so, it will probably be from the gate fluttering open at the wrong time, or from the load hitting too far away from the spine in a hard fall.
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csproul
May 13, 2005, 5:04 PM
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I have seen two carabiners break from falls on sport climbs that were low on a route (not a lot of rope out to absorb force). These falls were both on the second bolt off the ground and were long enough to put the people very close to the ground or just touching after rope stretch (long fall, not much rope out).
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ericg
May 13, 2005, 5:09 PM
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here's the link to the MIT website
http://web.mit.edu/aeroastro/www/labs/csi/climbing.html
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davidji
May 13, 2005, 5:15 PM
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In reply to: First, I want to say this is not a troll. I don't believe in the microfracture myths in climbing gear (yes, airplanes do experience it, but they go through significantly more loading cycles). I have read the Chris Hartman (BD tester) report on testing dropped gear (and every other thing I can find). My question is whether anyone has actually had gear break during a fall?
As far as the fatigue failures: it isn't just airplanes. Bikes fail pretty regularly this way. I've had both a frame and a fork crown fail from fatigue. Fewer loading/unloading cycles than an airplane, but more than a carabiner.
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