9/20 lathe motor is failing.

Hi Dennis, have you checked the capacitor. Or capacitors if it is capacitor start capacitor run ?

The original motor was cap start with a centrifugal switch....well at least mine was equipped so.

I binned the motor in favour of a 3 phase job with a vfd.

I also bought spare belts from Beeline Engineering in Milton Keynes at very favourable prices over any other supplier ( such as Warco/Chester)

Shout up if you think I can help..

If 3/4 hp motor is the correct one stick with it, the mounting will be correct. I think the motor will be 1450 rpm which is quite usual for small lathes. It's not difficult to overhaul your motor, because I think you centrifugal switch might not be closing or if as Pete Berry says ,it could be the capacitor which is in series with switch and the start winding. Before dismantling, mark both end shield/bearing housing using a steel rule and scriber, two scratches across one end, one the other ,these marks will enable you to reassemble the motor more easily and ensure the rotor revolves freely. As the motor is quite old be very careful with those very thin internal wires. Regarding the capacitor there is no simple way to test it with out a meter. You maybe able to borrow one, the actual value is not critical for test purposes. John

Are you on a 60 Hz supply? 1750 rpm sounds funny for 50 Hz.

I'd just replace the cap(s) with modern equivalents as a first step. The symptoms sound like a dodgy start capacitor. The motors themselves are nearly bulletproof except for the bearings but they should be fixable especially if ball races.

What sort of motor is your 2000 rpm one? A 4 pole induction motor will run at 1800 rpm max (maybe 1750 actual) on 60 Hz and a 2 pole maybe 3500 on 60 Hz. Anyway it's only 14% faster than your present motor which is negligible. As for the power, people don't seem to appreciate that power is the MAXIMUM the motor can turn out when fully loaded. It doesn't deliver any more power than the job absorbs, so if your worry is the belts breaking with more power, if you don't take heavier cuts it's no more likely than with the current motor.

As John says I would just try replacing the caps as it would be difficult to test them without test se

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As John said,these old motors are nearly bulletproof, most likely to be a cap problem,if so,just replace it,not that dear.