Crank set needs stress relief
12-20-08, 04:29 PM
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Crank set needs stress relief
Saw this in the For Sale forum:
"Campy SR 170mm 53/42 rings. MUST BE STRESS RELIEVED. If you dont know what 'needs to be stress relieved' means do not buy and do not ask."
Ok, I'll admit I don't know what "stress relieved" means. Can someone kindly enlighten me?
Dan
"Campy SR 170mm 53/42 rings. MUST BE STRESS RELIEVED. If you dont know what 'needs to be stress relieved' means do not buy and do not ask."
Ok, I'll admit I don't know what "stress relieved" means. Can someone kindly enlighten me?
Dan
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12-20-08, 04:42 PM
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This makes my "BS" meter read rather high.
12-20-08, 04:48 PM
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I think it means " If you are looking for a usable crank then don't buy these".
12-20-08, 04:49 PM
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Ok, "BS" or not, what does it mean? I've never heard of stress relieving a crank or rings or whatever.
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Last edited by High Fist Shin; 12-20-08 at 04:53 PM.
12-20-08, 05:27 PM
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I don't think it means anything. You can stress relieve wheels, but thats because they have different parts held together under tension. Cranks don't. Obviously that the post is really some sort of covert spy transaction.
12-20-08, 06:06 PM
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Campy cranks of that era are known to develop micro cracks where the crank attaches to the spider, a "stress crack". Folks keep the crack from running by grinding away the cracked area. I've never had to do this to my NR cranks so my description might be inaccurate. So the seller is sayin' the crankset has a crack in it...
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Last edited by cranky old road; 12-20-08 at 06:13 PM.
12-20-08, 07:20 PM
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Campy cranks of that era are known to develop micro cracks where the crank attaches to the spider, a "stress crack". Folks keep the crack from running by grinding away the cracked area. I've never had to do this to my NR cranks so my description might be inaccurate. So the seller is sayin' the crankset has a crack in it...
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12-20-08, 07:25 PM
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Campy cranks of that era are known to develop micro cracks where the crank attaches to the spider, a "stress crack". Folks keep the crack from running by grinding away the cracked area. I've never had to do this to my NR cranks so my description might be inaccurate. So the seller is sayin' the crankset has a crack in it...
12-20-08, 08:18 PM
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All of my NR cranks had that little crank, back in the 70's. Get a 3/16 inch small rat-tail file and radius the little web aluminum where the arm joins the spider, then use emery paper on the file and polish up what you file, you will likely file that the crack is very shallow and disappears after the filing... FYI i never heard of the cranks breaking at this spot
12-20-08, 08:56 PM
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Generally in metal working stress relieved means bead blasting the to relieve stresses that could lead to cracks in the metal. Roger
12-21-08, 09:45 AM
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12-21-08, 11:32 AM
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12-21-08, 11:43 AM
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Why didn't you just ask the OP of the cranks, he seemed more than happy to explain.
12-22-08, 11:03 AM
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There are lots of ways to remove stress.It can be done with temperature,sound waves,shot peening,vibration.Depends on what kind of stress your trying to get rid of.If your trying to eliminate stress cracks,the best way is to shot peen.That will compact the metal and spread the stress over a larger area.
12-22-08, 06:09 PM
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12-22-08, 08:29 PM
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The difference between bead blasting and shot peening needs to be clarified in this thread.
https://www.speedwaymotors.com/METAL-...INET,2606.html
https://www.metalimprovement.com/shot_peening.php
OT, but a new one for me is laser peening:
https://www.metalimprovement.com/laserpeening.php
https://www.speedwaymotors.com/METAL-...INET,2606.html
https://www.metalimprovement.com/shot_peening.php
OT, but a new one for me is laser peening:
https://www.metalimprovement.com/laserpeening.php
Last edited by kenja; 12-22-08 at 08:35 PM.
12-23-08, 11:34 AM
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The difference between bead blasting and shot peening needs to be clarified in this thread.
OT, but a new one for me is laser peening:
https://www.metalimprovement.com/laserpeening.php
OT, but a new one for me is laser peening:
https://www.metalimprovement.com/laserpeening.php
The laser technology is interesting; with the temperture component there might be a slight surface tempering effect as well as the mechanical effects.
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