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Material for crankshaft

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fidlstyks:
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.

steamer:
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.

Dave


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