On Feb 8, 5:05*pm, Bob Engelhardt wrote:
I have a 3450 rpm 3 phase motor on my drill press that I run up to 90 Hz
(5175 rpm). *It hasn't self destructed yet

A lot depends on the lube, bearings and balance of the motor.
A Dremel tool, for instance, goes up to 35000 RPM, but some
care is taken to balance it dynamically (and the radius of
the rotor is kept small). If a thermometer says the motor is
operating under its limit, you should be safe until it starts to
sound bad (shaft flex or harmonic resonances will be in the
clearly audible range).