[How do I?] How to change gearbox speed on Gorton 9J?

[TheSerialHobbyist]

It looks like a two speed motor that is only wound for one voltage. If the current motor is good. A transformer to step up the voltage to 440 may be the easiest way to go. If you replace it with a single speed motor you will sacrifice the spindle speed range. Using a vfd on a two speed motor would be a challenge. What I did with my Hardinge lathe that has a two speed motor was to used a rotary phase converter. That way I could keep the existing wiring and controls and still have the range of spindle speed. The mill looks like it is worth the effort. Keep us updated on the progress. Thanks for the pictures

That makes sense, thanks!

When you say that VFD on a two-speed motor would be a challenge, why is that?

With the original motor, the only way to change the spindle speed (other than the HI/LO switch) is to change the pulleys, which is obviously a pain. The speed control offered by a VFD would be really nice. Would that work if I were only using one of the motor speeds (either HI or LO)?

 

[Nutfarmer]

With a vfd it has to be connected directly to the motor without anything between it and the motor. I don’t know of any to change between the two motor speeds with out the controls originally designed to work with the motor. If a switch or contactor is used between the vfd and the motor you risk burning up the vfd. All motor control is handled by the vfd. Using the hi - low switch on the mill while powering with a vfd will burn up the vfd. There are smarter people on the forum that may know a way to make it work. You could hook up a vfd to either the high or low speed but not to switch between high and low speed.

 

[TheSerialHobbyist]

With a vfd it has to be connected directly to the motor without anything between it and the motor. I don’t know of any to change between the two motor speeds with out the controls originally designed to work with the motor. If a switch or contactor is used between the vfd and the motor you risk burning up the vfd. All motor control is handled by the vfd. Using the hi - low switch on the mill while powering with a vfd will burn up the vfd. There are smarter people on the forum that may know a way to make it work. You could hook up a vfd to either the high or low speed but not to switch between high and low speed.

Ah, I see, thanks!

I think I would be okay with keeping the motor on one speed and using the VFD to control the speed, if I end up going that route.