Single phase or three phase?

If you are just a beginner/hobbyist, go with single phase and plug and play. If you are going to use this more than once a week, go the other way.
 
I'd personally get the lathe with a single phase motor and avoid the hassles and expense of a phase converter.
I bought my first lathe with a single phase motor, then a bridgeport clone mill single phase with variable speed belt drive. No need for 3 phase. My whole cabinet shop runs on single phase as well.
That being said there are times 3 phase is a necessity. I bought a large lathe with a 10 HP motor, single phase wasn't an option so I installed a Phase Perfect converter to run it.
When I replaced the first lathe with a Colchester Student I converted it to single phase rather than run power to it and have to start the phase converter every time I used it.
That was latter replaced with a Hardinge HVL, single phase wasn't an option as it uses a precision balanced two speed motor that couldn't be replaced. At that point I had to install a 3 phase panel to power the Hardinge with lower current breakers.
I latter added a surface grinder. It was 3 phase but the panel was already there so powering it was easy.
Latter acquired a radial drill that was gear drive so not easy to convert to a single phase motor. I used a VFD on it rather than run 3 phase lines to it and have to walk across the shop to start the phase converter. But I only use it as a phase converter, the drill has 8 speeds on its own so no need for the variable function.
The Phase Perfect acts like a solid state rotary phase converter not caring about switching loads or motor sizes up to its limit, so machines are easy to run with it not having to alter any of the electrical controls.
Sometimes you can't avoid 3 phase but if you can why bother with it.

Greg
 
I guess the main reason I look for 3 phase machines is that in our are they are more plentiful, and less expensive than single phase machines. Most hobbyists either aren't familiar with, or don't want to deal with heavy industrial machines that use 3 phase power. That situation is not lost on those selling primarily to hobbyists. Similar capacity single phase machines are almost always more expensive. Not to mention industrial grade machines are built to higher standards.

I'm a bit spoiled having used industrial grade machines for the better part of my life. I like the accuracy, speed, and power of industrial grade machines. There is another thread running about a finish on an aluminum tube. One member was questioning whether his machine was capable of making a .010 deep cut. On any industrial machine that would be close to if not a finish cut. A heavy cut could be somewhere north of .250.

To me the willingness to deal with 3 phase power makes the pool of available machinery far larger than those only willing to consider single phase machines.
 
I’m thinking about purchasing a new Lathe and it is available in both single and three phase.In my shop I have single phase power only.Is it better to use a three phase unit with a phase converter or just order single phase unit and be done with it?
Thanks
I would never go 3 phase unless you have to. I have a mill and lathe both single phase, smooth and powerful.

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Well we have 2 BP mills at work both 2hp one single phase and the other 3ph. side by side. No comparison 3phz hands down
 
Well we have 2 BP mills at work both 2hp one single phase and the other 3ph. side by side. No comparison 3phz hands down
Would be great if you have the service. Not worth the extra expense to me to make FAKE 3 phase power.

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I’m happy with my 3phase lathe and roto-phase converter. I’ve never used a static converter but have been told they’re inferior to rotary phase converters which create that third phase.

My mill is single phase, and since I have the roto phase I’ve thought about putting in a 3phase motor but, well, there are more important things on the list.

Worst thing would be having no motor at all. It’s a good decision to get to make.
 
Are you thinking there will be any more machines in your future? If you are intending to get more machines, are you thinking of purchasing new?

Industrial machines from about the 1950's forward are very nice and widely available (at least in some places) - they are nearly always 3 phase and will often have multiple motors.

If you are purchasing new you will often get to choose single phase or three phase (same as what you are doing now). Of course what ever you finally choose, no reason you can't go down the other path at a later date.

I have about 9 (?) three phase machines connected and running (probably 15 different 3 phase motors) - I don't think it would be practical to run them on some sort of a VFD system. I have one drill press (3 phase) running on a single phase supplied VFD (it worked out easier in my shop arrangement and how the power was set up originally).

I am running all the machines off a 5HP rotary phase converter (my largest motor is 5 HP). It works awesome - I can just keep on plugging in more machines. It is true that the rotary units make a "fake" 3 phase power, but it works great and I have never had a problem.

There is a more deluxe option which has not been mentioned - using a Phase Perfect to get 3 phase power from a single phase source. Again, you can just keep on plugging in more machines to the capability of the unit. With a PP, the power quality is excellent - generally better than grid 3 phase as the voltage control is managed on site and not subject to the vagaries of the distribution system.

The VFD option is a good solution, but it is not "plug and play".

It really comes down to what you want to do with your machining. If you only plan to get the one machine (and with just a lathe and the usual small machines and work space + tools, you can have a very nice & capable shop). Lots and lots of iron really is not necessary to do much good work.

Single phase or 3 phase are both good options. If you are just doing an opinion poll - I'll put in my vote for 3 phase.

David
 
I'd be in the three phase camp. I paid $500.00 for my 7.5hp American Rotary converter. Had it for over three years and am very pleased. No problems. Of course I only run one machine at a time since there is only one of me in the shop at any time.
 
Please explain the meaning of 'fake 3 phase' in regards to an RPC...

-Bear
 
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