Crank Shaft Materials

[fidlstyks]

I have always made my crank shafts one piece of hot rolled steel. I have used cold rolled, but I had read in a book that one must cut out his crank outline and allow cold rolled  to warp before machining as the cold rolled will spring a bit. Then  after 6 months one may machine without further springing.
 I also have silver soldered links using cold rolled 5/16" rounds unmachined and flats.
  I have read on here that  some are using  4140 steel, p20 steel and 1144sp.
  Ideas ?

[Dave Otto]

I made the one piece crank for my Pacific engine out of 1144sp and it worked out real nice; there was quite a bit of waste though.

Dave

[Tjark]

I am making at the moment a one piece crankshaft from 4140 (42CrMo4) steel.
Availability is the main reason that I use this steel.

   Tjark.

[b.lindsey]

Clark, I use drill rod for the shafting and mild steel for the throws, good close fits, Loctite, and then pinned with small taper pins.

Bill

[petertha]

I'm interested in this too. 12L14 also seems to be another popular choice. I suspect because it machines so well & maybe 'sufficient' strength for many applications? Does anyone have experience machining both materials for crankshafts & can offer pro/con comparison feedback?

I've started collecting materials specs in spreadsheet form for my own purposes. Here are how these 2 materials line up.