I have the 3 phase Leeson motor hooked up to the Teco L510 VFD. It is running strong. I suggest this modig=fication even if you do not intend to convert to CNC. You can hook up a potentiometer to control the speed from the panel or just adjust it at the VFD. I have the stand offs turned. Now I just need to machine the mounts for the steppers and ball screws.