Lathe, electrical question

A lathe with any size to it is usually ran on Three
phase. Once in a while you can find a south bend or
Sheldon maybe others that run on single phase. I was
told you can not convert a three phase motor to
single phase.

Is it possible to get a 220 volt single phase motor
with the correct frame? Or would you need to
fabricate a mount for a single phase motor?

NEMA frame sizes are not not phase specific, if you can find a single phase motor with enough HP and same frame it will bolt right up even the shaft size will be the same,,BUT it is unlikely you will find one. A single phase motor of X HP will be quite a bit larger than a 3 phase of same HP, Voltage and RPM. Is it possible to covert the motor, yes, practical? No. VFDs get cheaper by the week it seems and they are a great means to take single phase to 3 and gain variable speeds at the same time.
NEMA frame chart

For what your going to spend on a large single phase motor and adapt it to your application, it will be money well spent just to get a rotary phase converter.

.
Some other ideas...

There are always posts suggesting the use of a VFD to get 3 phase, but your best, and cheapest route is to simply build yourself a rotary converter. All you need is a 3 phase motor with about 1.5 to 2 tmes the HP of the motor your wanting to power, a handfull of capacitors, and a couple of electrical contactors/motor starters.

That being said, if youcan find a company that works on commercial wells and sewer plants, etc they will typically have pump control units, etc that have been replaced that have both the capacitors and the motor controlers needed in them. In my case my dad works for such a place and I was able to get the items free, but most places consider that stuff scrap so you ought to be able to get everything cheap anyway. Along the same lines find a local scrap yard that takes in commercial electrical stuff. The contactors are the most expensive parts, if you had to buy them new, so i you can find an old commercial machine with a few of them in the control panel, again you can usually get them relatively cheap from those kinds of places too. As far as the capacitors go they are relatively cheap, especially if you check with somehwere like Surplic Center for the oil filled ones.

Before you do anythin though do some looking online and you should easily find quite a few sites that give you all the information you will need to figure out what parts to buy and how to put them all together into a working rotary converter. I built one last year for my milling machine using a brand new, bought off CL for $200, 10 HP motor and the components from two of three old well pump control boxes that had been changed out after lightening fried components I had no use for. Got it wet up so all I do is push a button to turn it all on, and then push another to turn it all off. Easy as pie and it works great.

Good luck and post again if you need any more help.

Up to 5 hp and for only 1 3 phase motor in the shop, a VFD is a pretty good option to run a 3 phase on single phase. Gives you variable speed. Don't end up with as much derating as a static convertor or the pain of a rotary convertor.

Soon as you get multiple 3 phase machines probably better off with a phase convertor.

If you have electrical stuff laying around you can make one starting with a larger three phase motor and instructions online. If you have to buy stuff to make one then a VFD may be the best way to go. I just worked on one today that cost fifty grand and punched a temp generator feed in the side to be plugged later . Foreman wanted the temp hole in the top . Oops [ but he never said that until I was done] I assumed..

Thanks for the ideas guys. I am not electrical sharp so I would need help making the VFD. I am not sure what VFD stands for, V must be variable. Is F for phase? And D for device?

I had heard that a phase converter was a pain so did not want to go that route.

An older fellow about a half mile from me has a 12" craftsman (Atlas) with a lot of tooling, and also a Bridgeport, in his basement. He will not part with the lathe or Bridgeport real soon. I would like a little heaver lathe and that is where the three phase would come in. I am not sure what powers the Bridgeport. Need to make a little room in my garage first.

Some of my comments are speculation on my part and others are questions, sort of. On a lathe, instant reversing has advantages. Easily done with 3-phase motors, requires special motor for instant reverse with single phase. A VFD works wonderfully to power a three phase motor (not multiple motors simultaneously) from single phase source. But I doubt that instant reverse is possible from a VFD-- never tried it. A disruption such as instant reversing probably will shut down the VFD. While I am not particularly a fan of rotary phase converters, the instant reverse might work better with the converter than with a VFD. But I never actually tried it.

I will be unloading a small lathe tomorrow morning for my home shop. It currently has a 240/480 motor on it. I am also getting a small VFD on a drill press, too. I need to research which will be more efficient on the lathe, since it gets run for long periods, use the VFD or get a 110V motor as I rarely reverse the lathe.

The VFD will give you an almost instant brake for an emergency stop, and it will also ramp up and down to speed slowly. Remember there is a lot of mass in the gear train to bring to a stop and reverse, so you don't want things happening too fast.

The VFD is very nice for making the machine run very slow for operations like threading.

Josh

Ive looked at 3 phase motor setups in country shops here.Not many 3 phase lines here.Rotary and static converters work and the slave motor system works fine.A friend built a small band mill and wanted to use a 3 phase motor.I lent him a booklet I had on 3 phase converters.He had the capacitors on hand and had the converter running in a short time.A new 3 phase line was put in here about 15 years ago, stops in front of my house.The slave motor system is the best one to build.Ive watch one run years ago.Those who crab about converters are extreme tightwads who never get much done because they cant part with money.

VFD = Variable frequency Drive. Not something that the average person could build at home.

It"s an electronic box that converts single to three phase. Protects against overloads. Allows soft starts. Instant easy reversing. variable speed. Torque control.
VFD"s are getting cheaper and better every day.
Anybody promoting a rotary converter is a dinosour living 20+ years ago in the past.

Guys were not reffering to making the VFD , but the {what I call ] the fake phase generator. Meaning having another old 3 ph motor laying around to start with. You need a start / stop a capacitor a small maybe 12X 12 puull box. A starter etc. Many intructions online how to wire . A VFD not so much . That you just buy and can run several machines.

A phase converter is easy to make...don"t need capacitors. Use a small single phase (1/2 or 1hp) to spin a three phase motor until it"s running, then shut off the small motor. google "home made phase converters" for ideas and wiring plans. I don"t understand where the pain comes in.

You can even kick or rope start that 3 phase, rotary phase converter, motor. All you need to do is get it started turning before applying power.

Dusty

I am not electrical, Don't like repairing anything electrical, let alone trying to build something electrical.
I would guess you would need a VFD for every machine that requires three phase?

Years ago I had heard of phase converters, did not understand them so I did not want one. I can wire 110 or 220 single phase things. We had an electrician at work we called two wire. That might be where I fit in, two wires and a ground. Looks like a VFD might be the way to go.