Student Mk1 motor

[RICHARD GREEN 2Participant @richardgreen2]

[RICHARD GREEN 2Participant @richardgreen2]

I have been given a Colchester Student mk1 lathe (1961), without any chucks or electric motor, it was originally 3 phase, hasn't been used for quite a while, but is in quite good condition, and I think has great potential as a restoration project.

Would it be possible to convert it to a 240 volt motor ( 3hp ), or should I stick to 3 phase with an inverter or whatever ?

It is a 1200 rpm lathe so would have a high start load in top speed.

It has a 12" faceplate, Imp and metric screwcutting, power feeds all ways, and imperial dials, so I think it's well worth restoring.

I have a nice 4 jaw in stock which would need an LO backplate,

So would only need to buy a nice 3 jaw chuck.

What does anyone think of the motor situation, 240 volt or 3 phase ?

Richard.

[WeldsolParticipant @weldsol]

I had a 1954 Student which was run from an inverter providing you set the ramp up time correctly and the max motor amp (as on the motor rating plate) set it should work ok , mine did.

Wire the motor direct and use the original controls for start / stop and reverse into the inverter (you are only switching inverter control voltage).

I now have a Harrison and a Bridgeport running from inverters with no problems for the last 8 years

Paul

[RICHARD GREEN 2Participant @richardgreen2]

Anyone else got an opinion ?

Richard.

[KWILParticipant @kwil]

I run the 3 phase 3Hp motor in my Harrison M300 from an inverter, however I have totally integrated the original control system and sequence into the Inverter set up. See article in MEW for the system. Like Weldsol I have no problems starting loads etc on the M300 or the Bridgeport.

[WeldsolParticipant @weldsol]

Hi KWIL I have intergrated the controls on my Harrison, but on the Student you can use the original switch gear as they are mechanical and don't use electrical latching.

What you should do is put an e stop in the power line to the inverter (these are about £30)

So if you do get into a situation you can kill the power

Paul

[Ian PParticipant @ianp]

Posted by RICHARD GREEN 2 on 08/05/2012 08:46:07:

Anyone else got an opinion ?

Richard.

Definitely three phase and a VFD. You wont regret it!

Ian

[Chris GunnParticipant @chrisgunn36534]

I was faced with a similar decision when the 3ph motor blew on my Bantam. I had run this for years with a single to 3ph converter made by Transwave. I looked at putting a new motor on it, so I could use an Inverter with variable speed and so on. If I went in that direction, I would need to do something to run the 3 ph coolant motor, as I use this a lot. When I costed it, just for the main motor, the new motor plus new inverter, plus controls, all from suppliers who advertise complete solutions, it was not cheap, and still did not give me anything for the coolant motor. In the end I got the old motor rewound, and continued with the 3ph converter, which enabled me to run the coolant pump as well, for a quarter of the cost of the new stuff. I know I do not have variable speed drive, but I can still use the gearbox, all carefully selected by the original designers, and I can use the coolant. If you have no motor to rewind and no converter either, the economics will be different for you. Inverters are not the only solution.

Chris Gunn

[RICHARD GREEN 2Participant @richardgreen2]

Is there anything wrong with using a 3hp 240 volt motor ? , I have no main motor or coolant pump so I could make the lathe all 240 volt, with a simple push button starter.

I don't know how the 240 volt motor would cope with the start load in the higher speeds.

Richard.

[Chris GunnParticipant @chrisgunn36534]

If you have got one, why not use it. Not sure what the starting current would be, maybe you should check this, as far as starting in higher speeds is concerned, if it is cold, my Bantam takes time to get to high speeds, as the oil is cold, when running from the converter. Once it has warmed up, no problem at all. If I go out and it is very cold, I run it for a few minutes at low speed until the oil has warmed up, then switch to the high speed.

Chris Gunn

[Phil LParticipant @phill]

one other factor which has not been mentioned is that single phase (240v mains ) is not as smooth running as true 3 phase 415v mains. this can transfer in to the sufacce finish depending on your m/c and other factors.

phil

[Phil LParticipant @phill]

one other factor which has not been mentioned is that single phase (240v mains ) is not as smooth running as true 3 phase 415v mains. this can transfer in to the surface finish depending on your m/c and other factors.

phil

[RICHARD GREEN 2Participant @richardgreen2]

Thanks everyone for your comments, I think I'll keep the lathe original, and fit a new 3 phase 3hp motor to it, and use all the original switching and reversing mechanism.

I've got a nice 3 phase coolant pump in stock, so I can put it in the lathe and make use of that as well.

The motor pulley is missing as well ( flat belt type ), does anyone know the diameter of it ?

It is a 1200 rpm Student.

Thanks,

Richard.

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