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mikedano
Jan 3, 2002, 6:09 PM
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I use BD Camalots, and I'm never sure when they are overcammed or undercammed. Of course I always try to get it sit at the halfway point, but it's never that easy. So my question is, when is a cam too overcammed or too undercammed? Can it still hold a fall when it's retracted almost all the way and you can barely get it out, or when it's barely retracted at all?
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saltspringer
Jan 3, 2002, 6:39 PM
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BD camalots can be used like nuts when they're fully deployed (ie: the cam heads are fanned out) and their passive strength in this configuration is enough to hold a fall. A cam is overcammed when there is no more reduction in the range when you pull on the trigger: it's very difficult to remove these cams because the second usually has to work to force the cam out since the lobes won't collapse any more. A tipped-out unit is one that is placed with the lobes at their widest with little or no room for expansion left in their range; in this instance, the cam doesn't have much margin for error & can walk out of it's secure placement with rope drag, etc...or, in the case of a fall, may be ripped from the rock since the cams can't expand more to create friction with the rock and hold in place. Cams are only effective when the force of a fall is properly transferred from the stem to the cams otherwise they'll just pull right out since the springs in the cams aren't made to secure the cam further than placing it and holding it until a force is applied
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atg200
Jan 3, 2002, 6:41 PM
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Maybe, and maybe. An overcammed unit will almost always hold a fall-but you owe your partner a beer for getting it out and you probably deserve penalty slack while folloowing the next pitch.
Undercammed units are much more prone to blowing, but can hold. In general, it is better to have an overcammed piece than an undercammed.
Get more different brands of cams. Sometimes a 2 camalot is undercammed and a 3 is overcammed, but a 3.5 friend is perfect.
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talons05
Jan 4, 2002, 2:48 AM
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That's a fairly difficult question, and the answer is that all cams are different. If you're asking when it becomes over/undercammed, the answer is not the same for a BD camalot as for a WC friend. I would suggest that you spend a lot of time testing placements on the ground to get a good feel for cam placement.
AW
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graniteboy
Jan 4, 2002, 3:48 AM
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I generally follow the rule that you should try to use a cam that is slightly more retracted, rather than one that is more expanded. If you have a choice between a tight fit in one size, or a looser fit in the next size down, go with the tighter fit. Tighter cams hold a little better, due to the equation governing their force transmittance to the sides of the crack.
Unfortunately, all this nice theoretical talk is often overshadowed by unruly reality. The fact that you may have used your last number 2 camalot in the section down lower may mean that you will end up placing the #1, in a more tipped out placement, up above.
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wigglestick
Jan 4, 2002, 4:30 AM
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A general rule that I try to use, although not very scientific, is to pull the trigger 3/4 of the way and if I still have to "stuff" the cam in the crack than it is probably over-cammed and may become a piece of history. Anything less than 1/2 way is probably under cammed and will either walk out or noot hold very well. But as everybody else said you sometimes have to place a less that optimal cam because you ran out of cams that size. Only once in my life have I had to rely on a camalot holding in the completely open position. Not comforting. To paraphrase another user from the site, either addriods or atg200 "That is like buying a chair because it can be used as a table if you have to".
I think I remember reading somewhere that the cams maximum holding power occurs when the cams are rotated 90 degrees. Look at the flat part of the lobes and pull the trigger. When the flat part is pointing straight down the stem, that is 90 degrees. I think
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rrrADAM
Jan 4, 2002, 9:53 PM
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Perfect placement of a cam is 25%-50% open.
Of course, that's only my opinion.
rrrADAM
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darkside
Jan 5, 2002, 6:03 AM
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Look for slight constrictions in the crack. While always a good practice, it can make a tipped out placement just that bit better or if it constricts behind(above) the lobes, it can reduce the tendancy to walk.
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how do you know when a cam is over/under cammed??
