Lost: 2 Black Diamond Cam on The Grack in Yose Valley
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Hi there, |
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Stuck due to heat expanded rock? How long was your partner's lead?! Unless it was hours long I'd say it was over-cammed, and is now booty. Moving on... |
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Ryan Huetter wrote:Stuck due to heat expanded rock? How long was your partner's lead?! Unless it was hours long I'd say it was over-cammed, and is now booty. Moving on...Guess that's better than claiming it was stuck by geologic shift... |
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Stacy Bloom wrote:Hi there, This cam was stuck due to heat expanded rock in the early afternoon on Aug. 9th. Went back to retrieve it in the early morn Aug. 10th and it was gone. Please contact me if you have any info about this cam. Thanks!Obviously the late afternoon heat completely mangled the cam and the cool night air released it into the talus below. |
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A few years ago I got a #1 really stuck on a route. I tried to get it out and couldn't. My partner tried and couldn't get it out. It was a warming/sunny day at Sauratown in NC just after a storm had left a bunch of ice around the base of the climbs. My partner filled a water bottle full of ice, climbed up and packed it around the cam and waited a few minutes, and then pulled it right out. Gear is definitely easier to pull out when it is cold and I love to hit all the popular easy routes first thing in the morning for booty retrieval! Got to get up there earlier! |
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You actually think a little bit of ice can contract rock? It couldn't be the melt water lubricated the lobes? |
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Maybe the ice cooled the aluminum to shrink the aluminum. It could also have been that it just needed another try and the ice had nothing to do with it. |
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My partner was a physicist and actually calculated/estimated how much the aluminum might have shrunk using its thermal coefficient of expansion. It was his belief that it actually shrunk the lobes a bit. And if it is only stuck by a fraction of a mm then that was all that was needed to get it out. |
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rocknice2 wrote:You actually think a little bit of ice can contract rock? It couldn't be the melt water lubricated the lobes?No, but it can contract aluminum. |
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Total booty man... That's a bummer... You lose some but surely you will get some back! |
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Yes it can contract aluminum but its still a very small amount. We are talking thousandths not fractions. |
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rocknice2 wrote:Yes it can contract aluminum but its still a very small amount. We are talking thousandths not fractions. Aluminum thermal coefficient is .0000125 in/°F So if a 1" cam @ 80°F = 1.0000" The same 1" cam @ 32°F = .9994" It's not even a hair smaller since a hair is .002.... so, you're spliting hairs? |
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Basically |
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Rock (flake) expansion and contraction due to temps: |
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rocknice2 wrote:Yes it can contract aluminum but its still a very small amount. We are talking thousandths not fractions. Aluminum thermal coefficient is .0000125 in/°F So if a 1" cam @ 80°F = 1.0000" The same 1" cam @ 32°F = .9994" It's not even a hair smaller since a hair is .002True, but a cam lobe is a 3 dimensional object, so wouldn't we be talking about that amount of contraction in all directions? I.e, is the thermal coefficient a linear measurement? If you calculate that contraction for an entire volume, what is the % of volume change? At the very least, you'd have to look at the contraction in two dimensions or on two separate lobes if ignoring the depth which is not in contact withe the rock. I'd have to think about the math for that one, and I'm no mathematician /engineer, so it might be no small feat for me. Since we're splitting hairs (that pun will never get old)...the thermal coefficient of 7075 Aluminum is 0.0000131 inch/degree F and a human hair is between 17-181 micrometers in width, which is 0.0007-0.007 inches, so the linear contraction is about the same size as a thin hair :) Plus, we're talking about a #2 C4 which is more like 1.75-2" in width when contracted. I know it's still small, but cams are sometimes stuck by just the tiniest of fractions. You can just get it to move, but there is a tiny something hanging it up. |
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csproul wrote: a human hair is between 17-181 micrometers in width, which is 0.0007-0.007 inches,I just measured the hair on my head and it's .0025". At .007 those may be pubes... and I'm not going there at work. In any case even if you did the math for volume it's nothing of significance. |
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haha I totally forgot this thread was actually started by a person looking to get gear back. |
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Scott McMahon wrote:haha I totally forgot this thread was actually started by a person looking to get gear back. bump.Which, of course, is much less interesting than the topic at hand. |
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csproul wrote: Which, of course, is much less interesting than the topic at hand.Indeed...she hasn't been back anyhoo |
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Gunks Jesse wrote:There are an incredible number if engineers on MP.And big swinging dicks but who's counting? This poor woman.. She will never climb on a hot day ever again. |
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I think glacial carving and climate change are involved. |