Looking at a new lathe, most are 3 phase so use a converter or change motor??

[Martin Turner 4Participant @martinturner4]

Hi, now I have my mill (240v) I have started to look for a small gap bed lathe, Harison M300/ Colchester Student etc.

Is it recommended to use a 3 phase converter and use the lathe as it left the factory or fit a 240v motor?.

I am not really bothered about a variable speed inverter as in the past most lathes I have used during my engineering career have had fixed speed motors and you just use the gearbox on the lathe for different speeds.

[Martin Turner 4Participant @martinturner4]

[Alan Waddington 2Participant @alanwaddington2]

On either of the lathes mentioned, it would be far easier and probably cheaper to use an inverter. There are also other advantages. You say you're not fussed about variable speed, but it really is a handy feature, as is soft start, the ability to reverse at the flick of a switch and the easy wiring of E stops.

Rotary phase converters are ok, but the drone of the slave motor can be a pain.

[larry PhelanParticipant @larryphelan54019]

Hi Martin,

Three phase has certain advantages,so I would go for a converter.. You never know when you will come across another good machine [3 Phase ],and then,you can use straight away,no messing ! 3 phase motors are better than single phase,any day.

[Martin NewboldParticipant @martinnewbold]

3 phase all the way my friend the other is voodoo or black science known only to a few. Its easier to blow your motor up too than 3 phase. Althought it seems expensive stick away from companies selling inverters unless you know what you are buying. asks friends or people that have working kit

More inportant than the motor choice is the gerbox that it uses to reduce the speed of the motor to the lathe. Not all motors run at the same rpm so it is important you know this and the hp of the motor minimum. There is a lot of debate about this. I have a small lathe with 1.5hp 3ph motor . Its brillant never underpowered. Some lathes have them already made or are available as an extra when you buy.

I made mistakes with mine costing me hundreds as I brought to low powered motor . I wish I had followed the advice of a friend and went with 3ph more expensive in first place . Have now been round the loop twice .

Martin

[Chris Evans 6Participant @chrisevans6]

Stick with the three phase, I run my 3HP lathe from a Transwave static inverter. Not perfect but trouble free for over 4 years now and all the lathe controls are as factory fitment.

[Martin Turner 4Participant @martinturner4]

Thanks for your replys guys, I know the basics with variable speed inverters as I am one of the maintenance techs at Southampton docks and our cranes and straddle carriers use them.

I did speak to Transwave today and the way the guy was talking a phase converter would run a 3 phase lathe from the box where as an inverter setup would require different wiring in the lathe and maybe even a motor change, does that sound right?

[Neil WyattModerator @neilwyatt]

Posted by Martin Turner 4 on 08/12/2017 18:35:06:

Thanks for your replys guys, I know the basics with variable speed inverters as I am one of the maintenance techs at Southampton docks and our cranes and straddle carriers use them.

I did speak to Transwave today and the way the guy was talking a phase converter would run a 3 phase lathe from the box where as an inverter setup would require different wiring in the lathe and maybe even a motor change, does that sound right?

The control gear for an inverter is wired differently as it all happens at low voltage.

Neil

[MuzzerParticipant @muzzer]

It's possible you'd need to change the motor to a different 3-phase motor if the original is a 2-speed jobbie like the one that came with my Bantam. Either way, I'm pretty certain that if you shop around, a new VFD will cost less than the equivalent phase converter (even if you need to change the motor) and allows things like soft start, jogging, e-stops etc even if you choose to spurn the variable speed features that come for free.

Murray

Edited By Muzzer on 08/12/2017 19:25:14

[BC ProfParticipant @bcprof]

When I was contemplating the purchase of a two speed Bantam a couple of weeks ago I contacted our local Motor Re winders . They were certain that the windings could easily be connected to give a single speed motor to run off of a cheap VFD . Since my lathe turned up with the Transwave converter at no charge I didn't need to pursue the matter

Brian

[Martin Turner 4Participant @martinturner4]

Posted by Neil Wyatt on 08/12/2017 19:11:32:

Posted by Martin Turner 4 on 08/12/2017 18:35:06:

Thanks for your replys guys, I know the basics with variable speed inverters as I am one of the maintenance techs at Southampton docks and our cranes and straddle carriers use them.

I did speak to Transwave today and the way the guy was talking a phase converter would run a 3 phase lathe from the box where as an inverter setup would require different wiring in the lathe and maybe even a motor change, does that sound right?

The control gear for an inverter is wired differently as it all happens at low voltage.

Neil

So by the sounds of it if I wanted an easy and quick solution used a 3 phase converter and the just plug the new lathe in.

I can see the appeal of soft start thought that can be programmed into a variable speed inverter, we did a basic inverter drives/PLC course at work a couple of years ago.

We had a training rig with a motor, variable speed inverter and laptop interface, I remember using the laptop to write a basic program that would soft start the motor, run it for 10 seconds, slow it down to a stop and then it would do the exact same in the other direction.

[Martin Turner 4Participant @martinturner4]

Posted by brian curd on 08/12/2017 19:40:08:

When I was contemplating the purchase of a two speed Bantam a couple of weeks ago I contacted our local Motor Re winders . They were certain that the windings could easily be connected to give a single speed motor to run off of a cheap VFD . Since my lathe turned up with the Transwave converter at no charge I didn't need to pursue the matter

Brian

Brian you didn't get your Bantam down South did you?

[BC ProfParticipant @bcprof]

Martin

Bantam came from Ware . Steve ( landylift) was only a little more expensive than a 'man and a Transit ' Steve moved that lathe tlhe length of a double garage and had it loaded on his transport in about 15 mins When he delivered it he had it off loaded and placed in my workshop in a similar time . No drama just cheerful banter

Brian

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