smjmitchell wrote:

4140 would definitely be my
choice when compared to 4130 for a crankshalf -- particularly if you need
to heat treat it.

I can't defend 4130 on all counts, but the crank uses antifriction bearings,
so high hardness is not a requirement. This probably influenced the
material choice. Further heat treatment is not called for in the plans.

Have a read of the differences between 4130 and 4140 in
MIL-HDBK-5 or USAF T.O. 1-1A-9 Metals Handbook and I am fairly sure you
will be convinced. You can download copies of both these publications.

Thanks for the references. I'll check them out.

Try Samuel (http://www.samuel.com/) for the 4130...

I'll give them a try.

--
Tom Young
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