rotary phase converters

I do not like them due to their very aggressive self marketing on wikipedia. Otherwise their converter will work. Consider installing a VFD instead of a phase converter. You may gain some functionality by going the VFD route (variable speed, electric braking, slow acceleration, and reversal), save money, electric bills, and reduce noise.

What is the full-load power rating of your Cincinnati mill.? This information will be on the motor's name plate.

If you're going to *buy* an RPC, do as Iggy says and get a VFD instead. MUCH better for the same money or cheaper!!

Few people here buy RPC's. An RPC is just a 3 phase motor with some capacitors and a relay or 2. Minimum is just the motor, a cap, and a push button switch. That's what mine is. Works fine. No, wait the minimum is just the motor and a pull-strap to get it going 8-) There is an endless list of build-yer-own-RPC posts in the archives.

And as Bob said, find your motor size, so you don't over buy or build. The referenced RPC's are likely 10 times what you need (15 & 20 hp).

Bob

Why not consider a single phase 220 motor? Mills don't have a high starting torque requirement, and mills have more than adequate gearboxes for speed selection. My 1929 Kempsmith has something like a dozen spindle speed selections with a flip of the levers.

Besides, horizontal mills were designed for constant input shaft speed. If you change speeds with a VFD you will affect the feed rate at the same time as the feed gearbox is run from a PTO off the input shaft. (at least on the older machines).

Tony

--FWIW I'm a fan of Phase-a-Matic stuff. I've had a solid state one on my Bridgeport for 30 years with no problems and I've had a rotary for maybe 20 years; intermittent use but again no problems. Another thing I like about them: they sell the solid state ones as kits. Website:

If you are going to spend money for new get the VFD. I'm using a rpc since I got a 5hp one for free.

Wes