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Material for crankshaft

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The crankshafts I make have diameters of 5/16 and 3/8". I cut coldrolled 1 3/8" x 1/2" for a 7/8" throw and a 5/16" crank diameter.

The 3/8" crank a little larger. What I did was cut out the cold rolled and let it set for 6 months before turning. I also cut them from hot rolled steel. I think the hot rolled balls up and does not machine as well, but when being careful it worked, and I machined them the same day. But I also put the blank in the surface grinder first. The scale makes the blank not flat.
     I also silver solder cold rolled in a 5 piece link. That is easy, but silver soldering like this takes practice. I have known people who said the press fit cranks like silver soldering and pinned them. I never liked that.

    The reason I am bringing this up is that I am wanting to forge some crankshafts and am wondering what steel to use. I do not think there is any point in having the best made steel. I am planning for now to use hot rolled steel. I also am using a die so that I can make cranks in a uniform appearance.
I have tried loading pictures from Practical Blacksmithing on how to forge a crankshaft, but it won't load.
Any thoughts on this would be apprciated.

For crankshafts with plain bearings, some carbon content is desirable.   It improves the durability of the bearing surface.   The problem I have is I've never specified a forging before.    That said, I think the basics of bearings must be the same regardless.    So a medium carbon steel would be a good starting point.

The forging portion of this is something that I think you will know far better than I.  I would look into the hot working ability of a 1144SP...It's a readily available, but I'm sure some experimentation would be required.



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