Re: [CAD_CAM_EDM_DRO] Re: spindles powered by REGULAR AC induction motor

Carlos Guillermo wrote:

> I regularly take my Bridgeport 1720-rpm motor to 150%, but I have
> no idea what the limit is. I'm also tempted to take a smaller
> motor and crank it slowly up to 600% speed to see what happens.

When I was going through my Millport head replacing bearings, I decided
at the last moment to do the motor bearings. Called a local company that
rewinds motors, they had them in stock. Got to talking with the owner
when I picked them up, mentioned running an inverter on the mill. He
cautioned me about running too high. Didn't go into a lot of detail, but
said that the higher you run the motor, the sooner it'll burn out.
Hinted something about higher voltages, or voltage spikes, that break
down the insulation. He said a significant percentage of his rewinds are
for motors that were inverter driven. Have no idea if this is all true
or he's just blowing smoke. However, I've seen ads for motors that are
rated for inverters. Lincoln or Baldor, I think. The ads mention voltage
spikes and insulation....

Jon