On Tue, 10 Jan 2012 10:09:20 -0600, James wrote
(in message ):


Hi Group, I've got to put my turning on hold. I just lost the motor on
my Jet lathe. It had a problem when I bought it you had to spin it to
start it so I took it in to have it looked at and had a new capicitor
put on. When I was using it yesterday it quit so I took it back to the
electric shop and they replaced the capicitor again and run the tests
on it again. It worked fine for a minute then tripped their breaker.
It's got a fault in it somewhere that's probably why the capacitor was
disconnected and it had to be spin started. Fortunately a new motor
isn't too pricey if you say it fast. If I had know for sure the motor
was bad I would have put the cost of the repair toward a new motor but
even with a new motor the lathe was still much cheaper than a new one.
Jim in ID


Did the motor make a loud humming/buzzing noise? Is the motor a single speed
motor? If yes to both of these questions, it is likely the case that you have
a split-phase motor. That is, it is an induction motor with starting windings
and an internal centrifugal switch that opens the circuit to the starting
windings once the motor gets up to about 70% of its normal speed. The
starting windings are a *relatively* high resistance, compared to the main
running windings, and the capacitor is used as part of the starting winding
circuit to provide a much higher starting torque. When the motor seemed to
work with a new capacitor - and then did not start again after the capacitor
burned out, suggests to me a partially shorted coil in one of the starting
windings. This would cause a very high starting current and a much diminished
starting torque - even with the capacitor. The high currents burned out the
capacitor. If this is the case the only remedy for this motor is rewinding
the starting coils, a prohibitively high expense in this day of automated
coil winding in new motor manufacture. (I did some of this kind of work in
trade school 45+ years ago.) A fresh motor is indeed called for. When you get
the new motor, if it is a split phase motor, have your local shop install a
4-way switch on the starting windings, so your motor will be reversible. If
they say it can't be done, go to a new shop or contact me for instructions.
tom koehler

--
I will find a way or make one.