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tradmike
Dec 3, 2003, 5:08 PM
Post #51 of 54
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Registered: Aug 28, 2002
Posts: 15
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Tradklime,
If we really want to know the right answer on cam pull out strength an independent test lab would have to go to work on some real life testing. Nothing works better when it comes to getting real answers. Theories are great and all but they are just theories. In reality, surface roughness and cam metal have a significant impact on pull out strength.
To come to an accurate conclusion on what type of cams work best for the different types of stone we could set up a test with several variables. We could test several cam sizes from small to large. Then for every cam size we could test from the skinniest to the fattest cam lobes with different types of metal from soft to hard with varying strengths for each lobe thickness. We would also have to vary the test surfaces. The cams with and without teeth and all the different types of rock that are commonly climbed would have to be studied. (Testing variables = cam size, lobe thickness, lobe metal, lobe surface (type), rock type, constant cam angle, etc.)
This is the only way we would have a good answer! Maybe the cam manufacturers already have this info! They are the ones making the trade-off decisions. It would be great information for the climbers to know. We could then make a logical decision on what we want to spend our money on. If you are climbing splitters it probably doesn't matter how fat your cam lobes are but other climbing areas would render them useless. Ahhh, the trade-off thing again!
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tedc
Dec 3, 2003, 11:24 PM
Post #52 of 54
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Registered: Nov 5, 2003
Posts: 756
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In reply to: Tradklime, If we really want to know the right answer on cam pull out strength an independent test lab would have to go to work on some real life testing. Nothing works better when it comes to getting real answers.....
Test.. we don't need no stinking test. If you want "real" answers look to reality and look no further than rc.com. Right here on this ng we probably have more "data points" that a lab could get in a lifetime.
So how about it folks speak up and share your data. Have you ever had a cam "fail" in a fall? If so why? Please speculate as to whether it was related to the strength of the cam (material), width of lobes, strength or rock, bad placement, other? My guess is that 99% are bad placements and probably not very valuable data points (but good stories none-the-less).
Personally, if I don't count crappy aid placements which can all be chocked up to bad placement (user error), my only semi relevant experience is the time I had a #1 Chouinard style (very thin lobes) camalot slide about 18" down :o and 2" out :shock: of a soft sandstone crack. The fall was like factor 0.4 on a good rope with an ATC belay. The cam lobes cut some nice grooves and then stopped. I have taken "harder" falls on the same rock with newer BD camalots with zero slippage. If my placement hadn't been as deep or the force had pulled more away from the rock this could have been kind of serious.
Any more "data points".
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tradklime
Dec 4, 2003, 1:50 PM
Post #53 of 54
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Registered: Aug 2, 2002
Posts: 1235
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In reply to: Any more "data points".
The closest I've come to a cam failure could have been classified as a bad placement. I placed a yellow alien in a shallow crumbly slot (only option). I fell on it and 1/2 of it pulled, and the other half held the fall. Each of the lobes that pulled had some sort of indent or groove, and both had little pieces of rock imbedded into the aluminum. My opinion is failure of the rock, but the some metal obviously sheared.
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ottoman
Dec 6, 2003, 4:17 AM
Post #54 of 54
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Registered: May 26, 2003
Posts: 149
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i like to find stuck cams...makes my rack bigger
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