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Topic Date User

Overcammed cams pull out at araps 13-Oct-2009 At 6:35:31 PM SteveC

Message

Its all there in these 2 short sentences from http://www.bigwalls.net/climb/camf/index.html (a good site
for the nerds)
"A logarithmic spiral cam (a "constant angle cam") ensures that the line between the axle and the point
of contact (the "line of force") is at a constant angle to the abutting surface, independent of how the
cam is oriented. Thus the force diagram for a given camming unit will be identical no matter how it is
positioned in a crack, i.e. whether it be compressed or expanded (figure 2)."

What you quote is actually a guide to placing them, not an indication of holding power. Placing cams is
important. For example if a 10cm cam was placed in a 9cm crack then loaded in a fall and the soft
sandstone fractured a little (say, 1cm) what is going to happen? These numbers are quite ridiculous in
their simplicity but should make the point clear. Now if you place a larger cam 'overcammed' in the
same 9cm crack then you have that margin of error to take up the slack of the softsandstonechoss. If
you are climbing clean granite on the other hand then you might consider a 'tipped out' piece as being
more worthy than the same placement in softer rock.

Personally i like to place all my cams in the lower range of expansion, and if i find an overcammed
piece of booty en route, i clip the shit out of it and yell to my second that i loosened it up for them and
so it is rightfully mine.