I've been running my Bridgeport mill with a VFD for years and never a problem. I recently acquired a larger lathe to replace my bench lathe. This is also 220v 3 phase machine like the Bridgeport but a little larger motor. Also operates on 220v 3 phase. I could go with another larger VFD for the lathe or just switch everything over to a rotary phase converter set up. Any experience out there to help me lean one way over the other? If I go VFD I have to go larger anyway or it will push the operating limits of the one I have. The one I have is only rated to 2hp which the mill is (but never pushed that hard). Also, it's a one person operation and only one machine is in use at a time.