Reply by Roy Turbett

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Posted on advice on purchasing a lathe

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Roy Turbett

168 posts in 3602 days

#1 posted 03-13-2012 07:50 PM

Jerry -

Don’t be afraid of buying a lathe with a 3 phase motor because you can add a VFD (variable frequency drive) for about $150 and will be very happy with the added functionality. I own three Powermatic 90’s. Two of them are the later “jackshaft” version that were built from 1971 into the early 90’s. The original 3 phase motors were swapped out for single phase motors. Two of the three “heaters” in the starter have to be changed because each leg of a single phase motor draws more amps than the legs on a three phase motor. (You only have to change two of the heaters because there are only two legs on a single phase motor instead of three.) By the time you buy a new single phase motor and change the heaters you will have spent more than the cost of a VFD and have less less functionality. My other lathe is a non-jackshaft version that was built from 1955 to 1970. Because the motor is mounted in the lathe bed, most single phase motors won’t fit the space because the capacitor cover gets in the way. However, I was able to replace the original motor (it was seized beyond repair) with a three phase 1 hp motor by reversing the bells on the motor so the capacitor cover pointed down instead of up. The VFD allows me to slow the lathe to a crawl by reducing the Hz while still retaining all of the mechanical advantage of the reeves drive.


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