Repairing a one-piece crank that is "twisted" at its axis, arms no longer at 180 degrees to each other?

[bloo]

When I asked a similar question on this forum years about forgings (not just cranks), I was advised to bend cold. That has mostly worked out well for me so far. I'm surprised by all the suggestions to use heat. Will it actually anneal the material? If it doesn't why do it? If it does, the material will remain soft and probably bend. There is also the issue of warpage when heating a part that must hold two bearings parallel and concentric. If it does now, will it still?

I speak of forgings here. Some one-piece cranks are just crap. Not all are forged, Some are brittle cast iron that might just snap off, and some are bent and welded from steel stock that is simply not tough enough for the job. The cure in that case is a replacement crank from Ashtabula, Schwinn, Sugino, Takagi, etc. In many cases, a 28TPI Schwinn bottom bracket set is also needed.
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[WillWork4Parts]

When I asked a similar question on this forum years about forgings (not just cranks), I was advised to bend cold. That has mostly worked out well for me so far. I'm surprised by all the suggestions to use heat. Will it actually anneal the material? If it doesn't why do it? If it does, the material will remain soft and probably bend. There is also the issue of warpage when heating a part that must hold two bearings parallel and concentric. If it does now, will it still?

I speak of forgings here. Some one-piece cranks are just crap. Not all are forged, Some are brittle cast iron that might just snap off, and some are bent and welded from steel stock that is simply not tough enough for the job. The cure in that case is a replacement crank from Ashtabula, Schwinn, Sugino, Takagi, etc. In many cases, a 28TPI Schwinn bottom bracket set is also needed.
.

Have you ever looked at a worn Wald Bottom Bracket or any brand cone with a straight taper? The bearing track doesn't always run concentric or straight...and those can still feel fine. Schwinn's usually stay in their groove, but I have seen them wear uneven too. I believe their size and design allow them to run with the crank spindle being a little bit out of round. Somewhere there's even a postwar Schwinn advertisement that boasts about how their bearings are meant to still perform even with run-out. That being said, I've never had a 1pc crank that didn't spin...unless the bearing surfaces were pitted or balls were shattered(shadoobie). European Bottom Brackets seem more susceptible to bends and binding...the ones with cottered cranks that I've had with run-out at least.

 

[MachuPicchu]

I have NEVER seen a "straightened" crank NOT eventually break...and they always seem to do so when you'd least want it to. If it's bent, live with it or replace it.

 

[Miq]

The annealed metal doesn’t stay completely annealed once you start to bend it back in place. It gets work hardened. Just like bending a paper clip. It starts out soft and that first bend goes easily. But as you keep “working” it, the metal work-hardens, fatigues, and eventually fractures.

I’d still bend it cold but buying a straight crank sounds like the best solution.

(Shmatta, shmatta, shmatta, I can't give it away on 7th Avenue)