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alldeez
Dec 3, 2013, 6:22 PM
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Probably like other climbers, there have been a few times where I've chosen to place an overcammed cam and continue leading, vs say placing nothing at all, backing off - or what have you.
My attitude has been to view those placements as basically psychological protection that probably won't hold (not to mention that the second might not even be able to get my cam out).
From my understanding and the BD literature it appears that a cam in this configuration can't expand/work like it can when placed in its prescribed range and might just pop right out with a good yank or not hold like it would otherwise.
Just wondering if anyone can confirm this or knows anything more about the effectiveness of overcammed cams.
thanks
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pfwein
Dec 3, 2013, 9:39 PM
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Could you cite the "BD literature" you mentioned?
I don't think you're right, and I've been directly told you're not right by someone I was talking to on the phone at Metolius years ago.
But I'm no authority, and I can't say the Metolius guy was either.
I've heard other people express the opinion that you have (they may not hold)--it doesn't make sense to me and I think it's climbing's version of an urban legend, but I'll keep an open mind.
Edits--just fixed some typos
(This post was edited by pfwein on Dec 3, 2013, 9:46 PM)
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acorneau
Dec 3, 2013, 11:39 PM
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Seeing as (most) SLCD's use a constant cam angle you will get the same "holding power" no matter where the cam sits in it's range.
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USnavy
Dec 4, 2013, 2:41 AM
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alldeez wrote: Probably like other climbers, there have been a few times where I've chosen to place an overcammed cam and continue leading, vs say placing nothing at all, backing off - or what have you. My attitude has been to view those placements as basically psychological protection that probably won't hold (not to mention that the second might not even be able to get my cam out). From my understanding and the BD literature it appears that a cam in this configuration can't expand/work like it can when placed in its prescribed range and might just pop right out with a good yank or not hold like it would otherwise. Just wondering if anyone can confirm this or knows anything more about the effectiveness of overcammed cams. thanks
(This post was edited by USnavy on Dec 9, 2013, 9:30 AM)
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kennoyce
Dec 4, 2013, 2:16 PM
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USnavy wrote: alldeez wrote: Probably like other climbers, there have been a few times where I've chosen to place an overcammed cam and continue leading, vs say placing nothing at all, backing off - or what have you. My attitude has been to view those placements as basically psychological protection that probably won't hold (not to mention that the second might not even be able to get my cam out). From my understanding and the BD literature it appears that a cam in this configuration can't expand/work like it can when placed in its prescribed range and might just pop right out with a good yank or not hold like it would otherwise. Just wondering if anyone can confirm this or knows anything more about the effectiveness of overcammed cams. thanks The primary risk with using an overcammed cam is that it will get stuck. Aside from that, I dont see why it would be less secure than an appropriately-cammed cam as so long as the cam has a constant caming angle throughout its entire range. If anything, I would argue overcamming makes the came more secure in that you have more outward force from the springs, which may help reduce the chance of the piece pulling in some situations, and it will help reduce walking.
Yep, as long as the cam has a constant camming angel (I don't know of any cam's that don't except for the metolius supercams), the holding power will be exactly the same for an overcammed cam and a properly cammed cam. Even the metolius supercams have a constant camming angle through the overcammed and normally cammed range, so this would be true for them too (the camming angle increases through the last 20% or so of their range which means lower holding power, but less chance of umbrellaing the cam).
Like USnavy said, the issue with overcamming a cam is not the holding power, but the fact that the cam may get stuck.
As far as overcamming the cam making the placement more secure, this may be true for some slick rocks (think limestone or quartzite). In slick rocks, sometimes the coefficient of friction is low enough that when you fall on the cam it will slide out of the crack without ever starting to expand, by overcamming the unit you are increasing the force of the cam on the rock wich increases the friction and may in some very particular scenarios keep the cam from pulling out.
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rocknice2
Dec 4, 2013, 2:33 PM
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In the case of small cams, the holding power increases when over cammed. The axles are a limiting factor and bend when catching a huge fall factor.
I have heard a story of a climber that whipped on a stuck cam and it ripped out. I would suspect that in that case the cam had been there for a while and got rusty enough to seize the cam action, not allowing it to work properly
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rgold
Dec 5, 2013, 2:29 PM
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Overcamming has no effect on holding power; that's the entire idea behind using a constant camming angle. (Because of their different construction, Totem Cams---not the basic ones---have slightly different holding powers at different levels of cam compression, but those cams are in any case stronger than other models.) Overcamming makes the placement more stable, at the (very considerable) expense of risking the ability to remove the piece. Small cams should always be placed with the lobes fairly tightly contracted, because otherwise rope motions might move the cam to a position in which the cams are fully open, and it doesn't take much considering the small range of such cams.
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csproul
Sep 8, 2014, 2:29 PM
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rgold wrote: Overcamming has no effect on holding power; that's the entire idea behind using a constant camming angle. (Because of their different construction, Totem Cams---not the basic ones---have slightly different holding powers at different levels of cam compression, but those cams are in any case stronger than other models.) Overcamming makes the placement more stable, at the (very considerable) expense of risking the ability to remove the piece. Small cams should always be placed with the lobes fairly tightly contracted, because otherwise rope motions might move the cam to a position in which the cams are fully open, and it doesn't take much considering the small range of such cams.
(This post was edited by csproul on Sep 9, 2014, 4:35 AM)
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curt
Sep 9, 2014, 1:12 AM
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csproul wrote: rgold wrote: Overcamming has no effect on holding power; that's the entire idea behind using a constant camming angle. (Because of their different construction, Totem Cams---not the basic ones---have slightly different holding powers at different levels of cam compression, but those cams are in any case stronger than other models.) Overcamming makes the placement more stable, at the (very considerable) expense of risking the ability to remove the piece. Small cams should always be placed with the lobes fairly tightly contracted, because otherwise rope motions might move the cam to a position in which the cams are fully open, and it doesn't take much considering the small range of such cams. This has always been my understanding as well. However, it was just pointed out to me that the BD instructions for C4 and X4's warns against overcamming. I can't imagine why this would affect the performance of the cam unless the cam angle is different for an extremely overcammed cam. Thoughts?
Most likely (as rgold indicated) there is a risk of getting an overcammed unit stuck. I can't think of any other reason and don't think it has to do with cam "performance" at all.
Curt
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