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General Climbing Discussion

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I Need Cams ! 8-Oct-2003 At 3:15:01 PM dodgy

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Different manufacturers use different allows for different applications (types of rock), normally 7075 (eg. Camalots) for hard rock and 6061 (eg. Aliens) for soft rock. There is a trade off in friction for durability. Comments on the Aliens have mentioned that the faces will mark under body weight. (From memory the smallest HB quads are brass).

What is required in a "smooth" crack (remembering that nothing is smooth if you look close enough) is for the alloy to push into the little holes between the crystals and increase the surface area of the contact patch. So if the coefficient of friction BETWEEN the alloy and rock is too low for the angle of contact, the cam will slip. If you could then swap the cam for one with a soft enough alloy or find exactly the same placement in rougher rock, the problem would disappear... So if you use Aliens in granite (for instance) you will get more grip, but you will also trash them faster.
Note also that the "cam angle" effects exactly how "flaring" a crack can be before slip occurs