Cirrus Crankshaft

[bobden72]

Hi Guys I have started to build the 1/4 Cirrus aero engine as per the Zimmerman design. To date everything is going as planed, I am now at the crankshaft stage. Which calls for some chrome moly steel 4140, well I have hunted and cannot find any. So I have decided to fabricate from silver steel, has anyone out there done this ? Can you see any problems going down this road ?
All advise greatly received.
Bob

 

[purpleknif]

4140 should be pretty common. Depending on size look for B-7. You can easily find B-7 threaded rod. Or perhaps a bolt you can turn.

 

[stevehuckss396]

You might have better luck with 1144SP. Stress proof has very little internal stress and wont warp as you remove metal. It's a very common material for model engine crankshafts.

 

[gbritnell]

I totally agree with Steve. Once I found this material I have used it exclusively for crankshafts. I cuts nice, stays straight and has good characteristics.
gbritnell