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Scott Brandstetter
08-12-2014, 10:26 AM
Electrical work is not my specialty.......

I have a Jet grinder that is 3450 rpm single speed. I was wondering if I can go to grainger type store and buy a regulator that will make this a variable speed grinder. Was thinking of using it with my Beale buffs. Any thoughts on what I would order, has anyone done this?
Dave Cullen
08-12-2014, 11:13 AM
Single phase induction motors can't be speed controlled. Sorry.
Steve Baumgartner
08-12-2014, 11:22 AM
Single phase induction motors can't be speed controlled. Sorry.

Not true. A Variable Frequency Drive (VFD) could do it.
Charles Taylor
08-12-2014, 11:34 AM
A Variable Frequency Drive (VFD) could do it.

Most single-speed grinders have capacitor-start motors, I believe, which aren't compatible with VFDs.
Dave Cullen
08-12-2014, 3:51 PM
Not true. A Variable Frequency Drive (VFD) could do it.

They only work with 3 phase motors.


Most single-speed grinders have capacitor-start motors, I believe, which aren't compatible with VFDs.

Correct. And the Jet is just that, according to the manuals.
John Lanciani
08-12-2014, 4:28 PM
They only work with 3 phase motors.



Actually, no. VFD's can be readily made to work on single phase induction motors provided that said motor does not have a centrifical switch. (Many European single phase motors dont use centrifical switches, they use either timers in the start circuit or operator controlled (push and hold to start) schemes).

I fully understand that this is not likely relevant to the discussion at hand but it is pertinent none the less for general understanding.