Bridgeport mill

[Russell Colvin]

I just purchased a Bridgeport mill. What is the best way to run
mill on single phase power?

[Gordon Maney]

The fact that you ask this question tells me you bought a unit with a 3-phase motor. The best way is to use a rotary phase converter, not one that is solid state.

[HWooldridge]

I agree with Gordon. I have a Bridgeport series 1 mill with a 3-phase motor that I run with a 10hp rotary phase converter. The solid state ones do not deliver the rated HP no matter what the advertising says. RotoGen (or RotoPhase) makes a good one. Hollis

[MoparNorm]

While I am thinking of it....

Just an e-Bay tip. When bididng on shop tools check the phasing first! Some 3 phase transformers can be very expensive. Converters do not really translate 3 phase to single without a massive loss of efficientcy(sp?) And very few if any residences have 3 phase power. If you do not have 3 phase power, don't bid/buy 3 phase equipment, unless you have absolutely no option.
MN

[Gordon Maney]

The other thing I would say with regard to buying or building rotary phase converters is that you want to size them adequately. Oversizing them is the most prudent approach, and you never know when you will buy some next piece of 3-phase equipment that you might want to run at the same time as the first piece.

Equipment surplused by industry that is 3-phase can in many instances be enormously cheaper than any single phase alternative, so that it makes it very worthwhile to acquire a rotary phase converter.

[Frank Irons]

I have been using solid state converters for my three phase machines for 22 years with no problems or noticeable lack of power.

Frank

[MoparNorm]

There shouldn't be a noticeable difference, but the equipment will not be operating at 100%. For the guys using the machinery on the weekends it won't be that much of a big deal.
However, if you were running 12 machines, 40 hours a week, you could pay for real 3 phase with the savings in electrical costs.
MN

[HWooldridge]

As stated above, I run the Bridgeport now and used to drive a surface grinder and a lathe. With the phase convertor running, I could start any piece of equipment, leave it going and start another so the max was a 1-1/2, a 7-1/2 and a 3HP motor running simultaneously. Of course, all of these devices start with almost no load. This was with a 10HP phase convertor running off a 50amp, 230v single phase breaker. A friend of mine bought the surface grinder, which had hydraulically driven feed and the 3HP motor then purchased a solid state convertor supposedly rated at 5 HP. He was able to start the grinder and grind by hand but engaging the feed caused the convertor to overheat within one or two passes and trip out. It may be that different manufacturers use slightly different rating systems but the rotary ones seem to handle higher loads than a comparable solid state unit.

I am told that 3 phase welders will not work with convertors but have no personal experience confirming that. However, many other types of good quality, industrial equipment with 3 phase motors are often available in used condition at very reasonable prices. In addition, getting 3 phase to most places which are not in a business or industrial area is usually expensive. Some farms have access and some do not. My friend is in a very rural area with 3 phase near the road but it would cost him about $13,000 to get service at his farm and that isn't justified for what he does. In his case, a properly sized convertor is just the ticket. I am also in a rural area and have a large single phase service with no access to 3 phase so I have to use a convertor but am quite satisfied with performance.

[Gordon Maney]

Frank has said that he has good luck with his solid state converter, and I am glad to hear that.

My experience when I was at Kwik-Way was that every time a customer got one of those things, adequately sized and even oversized, they had trouble.

We finally reached a point where we told customers that we would not support their installation if they had a solid state unit. No, we did not sell phase converters of any sort. We told them to shop elsewhere, and we did not profit from that policy.

[Russell Colvin]

Thanks for the information. It sounds like a rotary converter is the route for me. It also sounds like good advice to purchase one that is larger than what I need as the probability of adding more equipment is likely.

[Gordon Maney]

Originally posted by HWooldridge
I am told that 3 phase welders will not work with convertors but have no personal experience confirming that.

Some farms have access and some do not. My friend is in a very rural area with 3 phase near the road but it would cost him about $13,000 to get service at his farm and that isn't justified for what he does.

Your welder comment is interesting. I have never built one, but I have talked to people who have built rotary converters, using large 3-phase motors as the basis for the device. My recollection was that you doubled the size, meaning.... if you wanted a 5 HP converter you used a 10 HP motor. I think if you look on the internet you can find either plans to build one or a source for a book on how to build one.

I would think that a welder would work with a rotary converter, since it is effectively a 3-phase generator, creating actual 3-phase power. But, I have never actually seen it done. It is an interesting question.

I have seen so much 3-phase equipment sell for next to nothing, including beautiful trolley mounted chain hoists for $75 to $100 each, something all of us could use.....

I have 3-phase that runs right across my front yard, so to speak, in my rural area; it is farm country.

I inquired twice as to connection and minimum billing costs and I would never use enough to make it worth while.

[HWooldridge]

Lindsay Publications puts out a good little book of 15 pages called "How to Run Three-Phase Motors on Single-Phase Power". It's under $10 and gives the basics for building and using capacitor, autoformer and rotary convertors.

The theory on the welder not working correctly is that 3-phase from a converter is not as balanced as power from a typical commercial application, which could affect the characteristics of the arc. It might work but weld bead performance and appearance also might suffer.

[Gordon Maney]

Isn't Lindsay the group offering the neat old reproductions of books on machining?

[HWooldridge]

Yes, they have quite a few reproductions of old books on machining, blacksmithing and other metal working. I believe they reprint stuff that is out of copyright so a lot of the info is dated but still useful.