Single Phase To Operate This Lathe?

[Metal Head]

Hi,

I was just looking through EBay at various items and came across this lathe which the owner claims to be single phase (domestic):rolleyes:. The only lathes I have seen that size have always been 3 phase because of the grunt you will need!! Or am I way off the mark and that technology allows such large machines to be rum on single phase? If so would I correct in saying that it may cause the needles and maybe numbers to seize?

Cheers
MH


http://cgi.ebay.com.au/METAL-LATHE-NEW-VISBY-SINGLE-PHASE_W0QQitemZ150350047714QQcmdZViewItemQQptZAU_BnI_Woodworking_Metalworking?hash=item23018fa9e2&_trksid=p3286.c0.m14&_trkparms=65:1|66:2|39:1|240:1318|301:0|293:1|294:50

[19brendan81]

Mate I would be surprised if it were single phase, but I certainly wouldnt say its impossible. It depends where this is located and its history. Could be that the current owner is out of the way somewhere and cant get 3 phase thus converted it to single. Have you given him a ring yet?

[radish]

If it is single phase, then it's going to have a fair sized motor, just watch the dials on the electricity meter go WILD.

If it's a 3 phase motor, you can get converter to bring it back to single phase, the electric meter won't go wild with one of these fitted either. It will chew power, but not as bad as a big single phase motor does.

regards radish :D

[.RC.]

A 3 hp motor would run it OK..Top speed on a machine that old is not going to be very fast...Maybe 1000rpm.. it would have been built sometime between 1940 and 1960..

[Keith_W]

It can be possible to run a 3 Phase Motor on Single Phase but there are certain requirements, its call a Steinmetz Connection. I attach a pdf giving an example of this, for more information just google Steinmetz Connection.

Regards,
Keith.

[tanii51]

it is possible to have a 5 hp single phase but not all that common. In a past life we had a 5hp motor on a hydraulic wool press ( swer line to rural property)

[Metal Head]

Thanks guys for your replies.

Given that I don't have a great understanding of electricity I just wanted to know if it was possible to run off 240V? From the answers you gave me it only confirmed what I thought. I never intended on buying it as I don't need one - just yet!!

Btw it went for just over $2K

Cheers
MH

[Ropetangler]

If this machine has been fitted with a single phase to 3 phase VFD, then it would be possible to run the machine with it's original 3 phase motor, provided that it was a 415v when wired in star configuration, because by reconnecting it in delta, it becomes 3 phase 240v which is easily catered for with a VFD like the one mentioned above. Even if the original motor was 5 hp, which I would think is unlikely, 3 hp being more likely, it is not going to use that amount of power very often in an amateurs workshop, because we do not as a rule take big heavy cuts with high feed rates in really tough materials. The hobby lathe generally runs at a fast idle compared to one used in the production area of manufacturing, so it is not likely to cost a huge amount to run either.
For more info on VFDs, The Workshop Practice Series, No.16, "Electric Motors" would be one good place to start, or just Google VFD, or inverter Drives, or even do an eBay search for the same terms. Cheers,
Rob.

[19brendan81]

VFDs are gold. One of the blokes from TAFE who picked up the one of the same second hand lathes as I did used a VFD to get his running. It goes like a top. They are a very cheap way of getting 3 phase gear to run at home. Think is cost him $300 for the VFD and $50 for the motor store to make the delta/star modification to the motor.

I think you can run more tha one appliance off this VFD too, although its only rated to do one at a time.

[Ropetangler]

Hi All, as 19Brendan81 has said, a VFD is a good way to run a 3 phase motor off single phase, and while it is possible to run more than one machine off the one VFD, in most if not all cases, you should only attempt to run the one motor at a time. Even machines like milling machines with say suds pumps or traversing motors really need one VFD per motor, but you can say use a VFD on your lathe, and then on your table saw after disconnecting the lathe. Even this method will not run both machines at their optimum unless you set up the various parameters for each motor on the VFD. This can often be done so that both lots of data are stored and you just switch between them as necessary. That is how I understand it to be, but my knowledge is limited in this area and I stand to be corrected so feel free to do the correcting if I am wrong! It is normally the case that you should not switch between the VFD and the motor, so any built in switches on a machine need to be rewired to control the VFD, which in turn controls the motor, otherwise you risk damaging the VFD. The ramping up and down of motor speed can be set over wide range and it is often possible to have an Emergency Stop Button cause the motor to stop very very quickly ( on a saw say) if that is what you want.
If you do want to run more than 1 motor at a time, an option would be a Rotary Phase Converter, which if you know how, can be home brewed from salvaged parts for a reasonable cost, but for some reason they are not as popular in Australia as in the USA or Britain from what I gather. For more info see the reference to Workshop Practise Series "Electric Motors "I gave in an earlier post. There is also info on the Practical Machinist web site,
www.practicalmachinist .com
Cheers,
Rob.

[.RC.]

If you do want to run more than 1 motor at a time, an option would be a Rotary Phase Converter, which if you know how, can be home brewed from salvaged parts for a reasonable cost, but for some reason they are not as popular in Australia as in the USA or Britain from what I gather
Cheers,
Rob.

The main reason why rotary phase converters are not as popular in Australia is in the US their three phase is 220V, and while their household appliances run on 110V their houses also have 220V split phase connected to run items like hot water systems..

Here our three phase is 415V so any phase converter first needs a 240-415V transformer..Not an item you can easily procure..

[Vernonv]

Here our three phase is 415V so any phase converter first needs a 240-415V transformer.Not necessarily so. It is often possible to rewire a 415V star motor as 240V delta. This allows the motor to run off 240V rather than 415V.

Also (as is the case at my place) you can get 240V split phase supply (i.e. 480V - mainly seen in rural situations). I use the 480V supply and a static phase converter (without transformer) to run 415V motors.

[.RC.]

Not necessarily so. It is often possible to rewire a 415V star motor as 240V delta. This allows the motor to run off 240V rather than 415V.

Yes but you are restricted to 3hp or so as bigger motors are not easily rewired...Also the likes of some machines have multiple motors in them, usually for slide feeds..


Also (as is the case at my place) you can get 240V split phase supply (i.e. 480V - mainly seen in rural situations). I use the 480V supply and a static phase converter (without transformer) to run 415V motors.

Yes you can get it but the cost of getting it installed is more then a dedicated phase converter...

I had the choice of real 3 phase, split phase or a phase converter...I went the phase converter route as the $15 000+ price tag for real three phase was hard to swallow...And that was only to get it to the service pole..Who would have thought it would cost $15 000 to run one wire 300metres and a transformer..

[Vernonv]

Yes but you are restricted to 3hp or so as bigger motors are not easily rewired...Yes very true, although I have seen a few 5HP motors that allowed conversion.

Also the likes of some machines have multiple motors in them, usually for slide feeds..That's not really a problem. You can run multiple motors off the one phase converter. I run a panel saw (with separate main and scribber motors) and a dusty motor all of the one phase converter (at the same time - over 11hp all up :o).



Yes you can get it but the cost of getting it installed is more then a dedicated phase converter...

I had the choice of real 3 phase, split phase or a phase converter...I went the phase converter route as the $15 000+ price tag for real three phase was hard to swallow...And that was only to get it to the service pole..Who would have thought it would cost $15 000 to run one wire 300metres and a transformer..Yeah, I was quoted $50k to get 3 phase at my place - which I of course declined. As I already had split phase I decided to go for the phase converter. Split phase and SWER (both provide 480V) are quite common in rural areas.

[Fossil]

My home made phase converter supplies 240v and I can run motors up to 8hp. Most larger motors in Australia are built 415v delta, which makes them useless for a 240v 3~ supply, but there are motors up to 5hp 240v delta which often come up on ebay. I bought one the other day, for a spindle moulder that I want get up and running.

My phase converter uses 2x 4hp 240v delta idlers, so I can start motors up to 8hp. That is plenty of grunt for me, as the largest motor I am ever likely to run is 5hp.

Here are pics of the motor I bought the other day.