Straightening forgings... Who has done it?

[bloo]

Straightening forgings, like Schwinn cranks, and forged stems. Have you done it successfully? Cold or hot? Torch? Big pipe? Did the parts stay straight after the repair? I have a forged crank with a slight bend, and also stem that may have been more level a few decades ago.

I hear they straighten bridge girders these days by putting tension against the part, and then heating a spot on the stretched side, but not glowing hot. Something less than the original tempering temperature, like maybe 1100-1200f. The hot metal has nowhere to go since it is restrained, and so must compress a little, and then when it cools and contracts the stretched side is shorter. I thought I might try that.

I would love to hear your crank straightening stories......

 

[JAF/CO]

Your crank arms bent cold
So straighten they cold


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[AndyA]

Your crank arms bent cold
So straighten they cold

Yup. I've straightened a few using the cold/big pipe process.

 

[Rivnut]

Just straightened an Elgin fork three ways. Straightened the steer tube, aligned the steer tube with the forks, and aligned the forks with each other. Did it all cold with the help of a 20 ton hydraulic pressure my nephew built in Ag class in high school.

 

[bloo]

Thanks all. I guess it will be a big iron pipe with some copper for padding.

 

[Archie Sturmer]

This seems a good idea for a thread on “show us your mussed-up fork straightening examples” — especially those with burn marks, or vice clamp indentations.