Hi Rob about machining the main crank shaft diameter I had the same problem albeit on a 6" (half full size) traction engine model Dia around 1.5". I tried a travelling steady without any improvement. I eventually sent it out to a proessional machine shop to have it ground professionally on a cylindrical grinder but they couldn't do it either but they did machine it - kind of! I put the difficulties down to the material - a spheriodal graphite casting. If I was doing it again I would cut it from solid mild steel. (medium, not low carbon)
I don’t mind cast iron but the “skin” can be a pain. Or chilled spots. I’ve also thrown out the textbook figures for speed and feed, running way slower etc. Especially when using a tool with wide contact area - lots of chattering otherwise. Result has been drama-free machining. Good luck with the traction engine!
Thanks for that! I’ve only been uploading content for a few months but pleased with progress so far. A lot of the build was done way before I started my videos, I was encouraged to start my channel by others. Thanks again.
