I have considered putting vfds on my shopmaster bridgemill instead of using the step pulleys that came with the machine. what I have learned from the vfd supplier is that the motors are constant torque up to the base speed of 1800 rpm. If I use the step pulleys at 200 rpm I will have 9 times the torque at the spindle than the vfd will provide at 200 rpm out. Is there a solution for the torque decrease problem maintaining the same size hp motor other than taking a much lighter cut.
You should keep the step pulleys. If you install a VFD, you will not have to change pulleys very often but will still want the capability to do so.