Phase converter going in

I don't see a problem with running multiple machines with your compressor on that converter, but I've been wrong before. An electronic soft start would help. Only one way to find out..
I run my garage on a 5hp rotary that I built myself and got the leg balance dialed in pretty tight with the caps. I have an unbalanced 3hp rotary for the EMCO lathe and other stuff that is in the basement.