perfect retraction for cam lobes
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when i was taught to how to place a cam i was told that the perfect amount of retraction is where the straight part of the lobes line up so that the lobes don't overlap but there is not a gap between them when looking from a profile view. recently i was told, though, that this is overcammed. i am still very new to SLCDs so i figured i should ask. thanks |
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yeah, that's overcamming. It's not really that it won't hold a fall, it's more you might get the gear stuck so you won't be able to retrieve it. Usually about 40%-90% closed is considered the sweet spot. |
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There is no "perfect" when it comes to retraction. |
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If you looked from the side, I consider a proper cam to be somewhere between where the back of the lobes make a 90, to where they begin to touch (where you said), knowing that one end of that range is under cammed and one is nearly over cammed. Error away from the side you are worried about. |
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Not enough retraction -> cam could pull if you fall, either because of flex in cam and/or rock, or because cam walked a bit, or because small local contact (crystal) got crushed or deformed metal of lobe |
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If the cam is easily cleaned, it's NOT over-cammed, even if it looks like it. |
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DrApnea wrote:If you looked from the side, I consider a proper cam to be somewhere between where the back of the lobes make a 90, to where they begin to touch (where you said), knowing that one end of that range is under cammed and one is nearly over cammed. Error away from the side you are worried about. With that being said, most can retract beyond where they start to overlap, so your placement will still be able to be removed from what you said, and I'd rather have a cam hold and stuck forever then pop out because it was undercammedExactly...at least according to the Wild Country cam book and they know. |
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And if you are ever worried that your cam is overcammed or undercammed but feel like you don't have a better option, at least sling it long. I see so many people clip their cams short and then end up with all of the stems sticking straight out of the rock face or their gear stuck. |
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Perfect for what? |
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If I understand correctly, that seems ok to me. I was told anywhere from 0 to 45 degrees when I was learning how to climb. Here is a good post on cams from a blog that I follow... hopefully it helps! |
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As a general guideline (and in spite of my comments about not trying to decide by cam features that may vary from manufacturer to manufacturer), I'd go with the author's suggestion of a 45 degree cam lobe angle as approximately the most open the cams should be . But I think it is much easier to eyeball the angle between a pair of cam bottoms rather than the angle between a single cam and the stem (especially in horizontal placements, where the stem will not bisect the cam-bottom angle), so I'd convert the author's guideline to a 90 degree angle between cam bottoms. |
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The instructions for the C4 warns against "overcamming" with no further explanation. Never have really understood why they show this, except maybe to prevent you from getting your cams stuck. |
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thanks guys this really helped. i usually place my cams with the lobes about 0 degrees but it's good to know that, if it may be difficult to extract due to the topograhpy, i can safely go to around 30 degrees (the idea of 45 or even 40 degrees scares me) |
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I show folks the pac-man method |
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bearbreeder wrote:I show folks the pac-man method - pacman with its mouth in the "normal" position ready to gnom gnom gnom some ghost is good - pacman with its mouth just closed is ok - pacman with its mouth a bit more open is ok ... Unless its a small pacman - pacman with its mouth over bitting itself will work but ull probably owe me a cam when it gets stuck - pac man with its mouth wide open is bad - both side of pacmans mouth should be pretty similar - face pacman so his ass is in the direction of the pull Gnom gnom gnom !!! ;)I actually really like that explanation - lol. Makes perfect sense... |
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rgold wrote:As a general guideline (and in spite of my comments about not trying to decide by cam features that may vary from manufacturer to manufacturer), I'd go with the author's suggestion of a 45 degree cam lobe angle as approximately the most open the cams should be . But I think it is much easier to eyeball the angle between a pair of cam bottoms rather than the angle between a single cam and the stem (especially in horizontal placements, where the stem will not bisect the cam-bottom angle), so I'd convert the author's guideline to a 90 degree angle between cam bottoms. Still, this depends to some extent on the size of the unit itself: for very small cams 90 degrees is already getting to be too big, whereas big cams will tolerate more without risking too much instability. I really don't understand the generic concept of "overcamming" advanced by the author and others (with no explanations, I might add). It certainly has nothing to do with either holding power or stability. If the lobes can be retracted and the cam removed without a struggle, it isn't overcammed in my book. Perhaps the issue is that tightly compressed lobes can get overcammed with small amounts of walking if the crack tapers? Something to think about but not always an issue. Getting the stems oriented in the direction of the load is important. Cams placed in pods in vertical cracks and sticking straight out are unpredictable if the pod prevents the cam stem from aligning in the direction of the load.Do not quote me on this, but from my understanding I do not think overcamming is really as much of a strength issue as it is an am-i-going-to-get-my-cam-back issue. The problem with overcamming is any walk at all and you might as well have just pounded in a piton. I have lost like 5 blue master cams by overcamming them and then never being able to get them out. Again, that has always been my understanding, but I am not an authority on the topic. It would actually be interesting to reach out to BD or Metol. and ask... |
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While we're on this topic, does anyone else think they should be placing a #3 here |
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Conor Mark wrote:While we're on this topic, does anyone else think they should be placing a #3 hereThat looks OK to me. |
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Mike wrote: That looks OK to me.Would be pretty funny if the BD boys had a bad placement in their website shot for cams - lol. Placement looks good to me, but if I had to choose, gun to my head... it leans more twd the undercammed spectrum in my opinion. Depending on if there is any flair in that crack a good case could be made for a number 3 for sure. |
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Jake Jones wrote:Larger cams (by my own definition are #1 and up) are much more forgiving. I won't think twice about putting in a #3 with the tips of the lobes intersecting each other (from a profile view), but try to stay away from it with smaller cams.Interesting experience Jake, I've personally found the opposite to be true. I've only lost 2 cams due to overcamming, a BD 3 and 5. Both probably could have been removed, but were on big climbs in Zion where it was more important to keep moving. With small cams (BD 0.4 and smaller), I will usually retract them fully and try to slot them like a nut. Usually removal is no big deal, if the follower removes them the same way they went in. CCase wrote:Again, that has always been my understanding, but I am not an authority on the topic.Rich is an authority on the topic, and you would do well to listen to him. |
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Conor Mark wrote:While we're on this topic, does anyone else think they should be placing a #3 hereI've climbed that size crack. That's the right size. A #4 might barely fit in there. In fact, I have used a very tight #4 and a loose #3 in conjunction with each other to get through that size. The rule of thumb I use is: take the full trigger pull, then divide that pull into thirds. Placing at about 2/3 is generally "good." But as previous posters have suggested, ANY retraction in a perfectly ideal crack has the same holding power; walking and overcamming/getting stuck are the problems. |