Older lathes

[Tom Kitta]

rotary phase converter is about as noisy as the motor that is used. Usually rotary is based of a single motor & a capacitor bank - but there are other configurations - such as two motors (one single ph motor powers three phase generator motor - some mods are needed as its not as simple as connecting the two). Or a pony motor and main motor.

VFDs are quite quiet - they may have noise from a large cooling computer fan.

 

[kevin.decelles]

In the single motor rotary solution -- the motor is 3ph correct? 3ph is what I remember reading about. The capacitor bank is used to bump start the motor......

In the two motor state, the pony motor replaces the capacitor bank and you can dis-engage it after the 3ph is rolling?

Like @PeterT I too am curious. I've started a @Tom Kitta collection of motors here too, and I have a nice 7.5hp 3ph that is begging to be 'converted'.

 

[Tom Kitta]

Yes the motor is 3ph motor that produces 240v and is say 1700 rpm. Capacitor bank is sized to start the motor and also provide some running capacitance. Still my wild leg is 270v. The 3ph motor is connected to 2 phases form your utility and 3rd phase is "generated" aka wild.

I have dozens of motors.

Yes some people use pony motor to start but you should still have some run capacitors. Its more compact solution to simply have all capacitors in one box - pony motor takes space and you either need to turn it off or wire in centrifugal switch to auto turn it off.

 

[Millwright1009]

May have a lathe a bit more common lined up. If the price is right that is. This one is older but is 240v 3 phase. Easier to work with.