Have lathe and milling machines with VFD's and 240v 3 phase motors. Thinking about running vfd's from potentiometer and switch for fwd/reverse. Think I would prefer potentiometers to be switched and I would fit a seperate switch for fwd/rev . What would be the prefered potentiometers and switch for me to get? I would also need a couple of plastic boxes or something similar to fit them in