110v or 220v for lathe

[customcutter]

The motor on the Birmingham CT-1440G is a 110/220v, 1 ph, 2HP. However, it is a 4 pole instead of a 2 pole.

I've read in my last couple of months of research that 3ph motors make better cuts than 1ph motors.

Just wondering if 110v or 220v makes a difference in quality of cuts. I'm sure I can reverse engineer this thing to figure out how to get 220v if it makes a difference.

I'm guessing that a 4 pole motor would run smoother than a 2 pole and therefore make smoother cuts? Maybe that is why 3ph motors make better cuts, maybe they were 1ph 2pole motors?

Just wondering if anyone has any insight, 110v or 220v.

thanks,
CC

[darryl]

For the most part, if you have the option to run on 220 instead of 110, then it would be better to wire it that way. The current flow is less for the same power level, and motors seem to get up to speed faster.

Being a 4 pole probably means that it's a slower speed motor with more torque than the higher speed motor. I don't think there's any difference between a 4 pole and a 2 pole being 3 phase or not- the 3 ph motor would probably run smoother than a single ph with either configuration.

Maybe you have an 1100 rpm motor- that's what my lathe came with. I don't know if it's 2 pole or 4 pole though.

[customcutter]

The motor is 1750 rpm I'm pretty sure. Not sure of anything lately. (I was looking at some other motors I have to see if I had something that might fit if the original was bad. Several of them were 1750rpm.)

Just thinking that 4 fields pushing/pulling the rotor would be smoother than 2. I don't have a clue how many windings/fields are in a motor.

thanks,
CC

[J Tiers]

4 pole is 1725 or so rpm (1800 is synchronous speed for a 4 pole) including slip at full load.

2 pole is 3450 rpm or so with slip (3600 is synchronous speed).

I doubt that 240V vs 120V will make a lot of difference, if any, in smoothness. The motor has the same power either way. if anything, the 140V has a bit better acceleration, and may be "more like single phase" than 120V, with the same faults, only more so.

For smoothness, not a thing to choose between them, really, although the 3600 rpm unit will probably have more "stored energy" due to the higher RPM. Whether that translates to "smoothness" is debatable (so is the definition of smoothness).

The 3 phase will be a lot smoother than either..... about 14% variation in torque in the ideal case, while single phase has 100% torque variation every cycle.

When I switched over I found that

1) the three phase had a great deal less chatter. Much of my chatter was at the torque ripple frequency.

2) with 3 phase, the flat belt drive slipped a lot less

3) if it did slip, I could often "recover" by slacking the feed, where with single phase I could not recover, the belt would slip off and need to be replaced on the pulley.

4) Cuts that I expect to cause slip, based on the single phase performance, mostly do not slip with 3 phase..... I can "push it" much farther if the belt is clean.

I put this down to the fairly extreme "pulsing" of the single phase.... the jerkiness is more likely to start a slip, and once slipping, it won't be as easy to 'catch up" and stop the slip.

[Willy]

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Maybe you have an 1100 rpm motor- that's what my lathe came with. I don't know if it's 2 pole or 4 pole though.

Darryl a 60 hz 1100 rpm motor would be 6 poles.

[darryl]

6 poles, yeah that makes sense.

[customcutter]

J Tiers:

Thanks for the explanation. I'll leave it 110v, that's easier than trying to rewire the control box without the manual. If/when necessary I'll consider upgrading to 3ph.

thanks,
CC

[customcutter]

Just found this in the "Favorite Threads" sticky.

http://bbs.homeshopmachinist.net/sho...7&postcount=37

thanks,
CC

[Clevelander]

Just a question.....

Do you have three phase (to the building) where you're using the lathe? No typical homes have three phase power and even many commercial buildings don't have three phase power; or were you considering getting a three phase motor AND a three phase converter?

[customcutter]

Yes, I have 3 phase power from a rotary phase converter that I built years ago.

Ken