rotary or a vfd, garage, 3hp that already lies

The 3hp on the Sheldon is three phase. The garage is not. I have a rotary someone gave me that sounds like a bad bearing and a sermon, and a VFD quote that assumes I understand grounding. Butte. Winter. I would like the spindle to turn before April.

If the motor is inverter-duty, or at least not ancient with questionable insulation, a VFD is the cleaner tool and you can actually use the speed knob. A tired rotary adds a second machine to maintain. What is stamped on the motor, and is the lathe contactor staying in the circuit?

Do not put the VFD on the output of the existing drum switch if you can help it. Feed the motor from the drive. Switching the output under load kills drives. Also 3hp needs real wire, not the extension cord from the heater.

I ran a VFD on mine for a year off a regular outlet and it was fine. People overthink the grounding.

Ken, 'fine for a year' is not a wiring practice. Harold, if you can read the nameplate, do the VFD and pull the drum switch out of the motor legs. The rotary you described is a future fire with a bearing number.

Motor is a baldor, 1980s, not inverter-duty by the stamp. I bought the drive anyway because the rotary howled louder when I spun it by hand. Drum switch is out of the motor circuit. It turns. It does not smell. Ken, I'm still grounding it, out of cowardice.

cowardice is the correct wire size. mine hummed for a week before i admitted the cord was a lamp cord. dont be me