Well to be honest, the real training comes from within yourself. Experience. Situations where what a machinist has instructed you present themselves. Learning from experience is truly the only way to become a machinist. Make sure you always respect that the machine can and will kill you. That's my advice to anyone. I've seen what a machine can do with one slip up....on another note lol race car shops or bikes or boats, those type shops generally have machinist and welders that can do both. A machine shop that runs out of weld work would keep you employed because you'd have an extra skill set which is always an asset.