I'm making a Stuart Turner (type) triple expansion steam engine, and need some advice please. The crank shaft is about 9" long, and the throw is 1/2". My first attempt to manufacture out of solid (but with balance weights added separately) was with a piece of steel of unknown pedigree. Although rather difficult to machine, all went well (using very sharp tools) until I milled out the excess material between the crank webs. The shaft then took on a "bend" - I presume this is because of internal residual stresses becoming unbalanced as more material was removed from one side of the bar than the other (?). I have abandoned this piece, and have now sourced a length of 1
3/4" (42mm) pedigree EN1A. The question is, should I try to stress relieve this before I start to machine it, and if so, is "cherry red for an hour and cool in still air" an appropriate recipe? Any other comments / observations would be welcomed.Mike D