I purchased a used chevalier milling machine and have it running with a vfd. It is a variable speed machine. I use the mechincal variable speed to change speeds. When I run it in low speed the spindle turns in the correct direction with the switch in forward. When I shift to the high speed with the lever, the spindle turns in reverse with the switch in forward. When I change to reverse on the switch, the spindle rotates correctly. The motor is not changing direction when the hi/low lever is moved. The switch changes the motor direction. I have run Bridgeport and other off brands and I do not remember having to change the switch position for correct rotation. Of course at 71 and not having run a mill in a few years, I might be remembering wrong.