Bridgeport type milling machine motor

Mike M · Aug 16, 2011

I have a Millport milling maching which is a copy of a bridgeport. It has a 3 phase 2 speed reversible motor. I was wondering if anyone has found a 1 phase motor to work as a replacement or had the 3 phase one rewound to 1 phase ?
Found someone on ebay selling a conversion for the single speed motor to 1 phase , but they don't have the 2 speed yet. Plus they are a little pricy.
Any info may help me. Thanks.

Kansas Cockshutt · Aug 16, 2011

If you don"t want to make your own phase converter, and want to replace motors, get a VFD and then have infinite speed control.

grandpappy · Aug 16, 2011

you can buy a 3 phase converter box. not very expensive. they work ok. may lose a little power.

37chief · Aug 16, 2011

On my mill I used a Phase O Matic static phase convertor. For around 100.00 you can find one on EBAY. If you use this you will lose some power, but unless you are taking very large cuts you wouln't notice the difference. Stan

Jeff NWOH · Aug 16, 2011

If you can get an old 3 phase motor slightly larger horsepower-wise than the one on your mill, you can build a rotary phase converter for next to nothing. Try google, tons of info out there.

VFD would be a good option as well, especially if your mill isn't variable speed.

Either would be considerably less expensive than replacing the motor.

Jeff

Mike M · Aug 16, 2011

I have heard that VFD were expensive.

I have used the converter box in the past,but think it may of goofed my motor up. It got VERY hot the other day.
My electric service where I relocated is marginal,but runs the 220 lathe fine. I'm thinking the converter doesn't handle well with voltage drop.

Tony in Mass. · Aug 16, 2011

That's the brand I have powering my Bridgeport. I don't do heavy cuts either, so I don't notice anything. Got to follow directions to the letter. All the other options are alot of money

Kentb of SWMO · Aug 16, 2011

Find yourself a 3 to 5 HP three phase motor and make yourself a Rotary Phase Converter. A rotor will let your use the two speeds you have in your motor now. You can INSTANTLY reverse your mill motor if you need to. You can not do this with a Static Converter and I am not sure but I do not think you can do this with a VFD. When using a VFD, You have to do the reversing with the VFD. Also, ALL three phase motors are reversible. All you have to do is switch the connections of any two of the three power input wire for the motor to reverse.
The Rotary Phase Converter I have I built from a 3 HP three phase 1200 RPM motor. When I first built the converter, in the summer I could roll the shaft with my foot and apply power to start it. In the winter I had to use a starting rope. Later I added a auto-start time delay circuit with start capacitor and still later I added run capacitors to reduce the idle current. I did this over a few years as I could scrounge the need parts on the CHEAP. Cheak practicalmachinist.com The have a sub-forum just on building Rotor Phase Converter/VFD"s.

Kent

Andy C · Aug 16, 2011

Save your money ....get a VFD They are comming down in price. I recently bought one for $285. I have one on the Clausing lathe. Used it to replace the variable drive which was shot. very nice piece of equipment. Will soon unhook the phase converter in the shop. The downside of VFD is that they will only run 1 machine at a time

Bridgeport type milling machine motor

Mike M

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Kansas Cockshutt

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grandpappy

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37chief

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Jeff NWOH

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Mike M

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Tony in Mass.

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Kentb of SWMO

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Andy C

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