I used a VFD on my orac. Using linuxcnc but would work equally well with mach3
Mach3 will struggle with threading as it only uses a single pulse per Rev to sync the spindle to the Z axis
I cut perfect threads using the original orac spindle encoder. 48 pulses per Rev so syncs 48 times per Rev which is very important on a small lathe that will bog down under threading loads as no back gear etc

I get good torque out of the orac three phase motor and spindle speeds from 50 rpm ( for clocking not cutting ) to 2200 rpm

Paul


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