Vintage lathe meets 21st Century

[Andrew Davies 4Participant @andrewdavies4]

[Andrew Davies 4Participant @andrewdavies4]

i have just modified this lathe with a permanent magnet 3 phase motor and vector inverter.

This gives constant torque from 0rpm all the way through to max speed.

See film for advantages

https://youtu.be/Un-uvkEhPEI

[HopperParticipant @hopper]

Neat. Great to see the old iron still being used in anger, with 21C tech.

[Brian WoodParticipant @brianwood45127]

It was especially clever to see the method he uses to positively keep the chuck key away from the chuck while power is supplied to the spindle.

There was a very graphic safety poster [among others equally unpleasant] at the Rolls-Royce apprentice training school in the 1960's of a young chap wearing his chuck key in the middle of his forehead, it was meant to shock and it did just that

Brian

[DanielParticipant @daniel]

His chuck key safety device is brilliant.

Of course, modern lathes have overcome the problem through the safety guard

cut out switch.

Love it, though. Well done that man !!

[not done it yetParticipant @notdoneityet]

Brian,

While a superb idea which could well, or should, be employed on other installations, it will, nevertheless, not be foolproof. There will always be the odd idiot who would bypass the safety with a bolt, or have two chuck keys!

The better inverters are always a plus.

[Paul White 3Participant @paulwhite3]

Hello Andrew.

I am also a mover into the next century of old equipment capability. I'm very impressed by your drive system, can you give more detail of motor and inverter.

Many thanks Looking forward to your next posting.

Paul.

[Ian PParticipant @ianp]

Very interesting but what is a 'permanent magnet three phase motor'? and how does it interface to a vector VFD?

The motor shown looks like what is usually described as a 'brushless servo motor' and would normally have an integral encoder. Connected to its driver electronics it would have the same characteristics as described in the video. As far as I understand it that setup would cost significantly more than a standard motor and VFD.

Ian P

[richardandtracyParticipant @richardandtracy]

Posted by Daniel on 10/04/2018 10:53:09:

…Of course, modern lathes have overcome the problem through the safety guard

…

Chuck guard & safety switch were the first things to be removed from mine. If I'm stupid enough to mince my fingers in the chuck, that's my problem. Wretched things get in the way & waste time.

Regards,

Richard.

[Ian PParticipant @ianp]

I too would find the chuck key safety device a pain. I have switch on the lathe with the key in place, so far without any consequences other than being annoyed at my own stupidity.

Since we have excellent electronics controlling motors nowadays my suggestion would be that the spindle rotates one full revolution at a low torque setting before the selected spindle speed is implemented. That way the key would fall out of the chuck harmlessly. I think I would get used to the small delay every time I switched the motor on but it could be disabled when using collets.

Ian P

[John HaineParticipant @johnhaine32865]

This link might help with the motor.

[MWParticipant @mw27036]

This is the Video;

Michael W

Edited By Michael-w on 10/04/2018 15:13:32

[Ian PParticipant @ianp]

Posted by John Haine on 10/04/2018 15:04:02:

This link might help with the motor.

Well it gives a good description of various motor types and compares their features but until the OP identifies what motor and controller he actually used we wont be any wiser.

I have a feeling that whatever it is, its expensive!

Ian P

[Neil WyattModerator @neilwyatt]

Looks like a BLDC motor as used on the Arc SC4.

Permanent magnet, 3 DC 'phases'.

[Jon CameronParticipant @joncameron26580]

Posted by Neil Wyatt on 10/04/2018 16:12:48:

Looks like a BLDC motor as used on the Arc SC4.

Permanent magnet, 3 DC 'phases'.

Interesting, if neil is correct this means that there is a few possibilities to combine the old with the new. Take the control unit and motor from a mill, and hook it up behind the lathe with a handy stand for the good old well build lathes. A new lease of life.

[John HaineParticipant @johnhaine32865]

Well he does say he uses a "permanent magnet 3 phase motor and vector inverter" which maps directly on to a type described in the article I linked. You could also call it a brushless DC motor.

[Ian PParticipant @ianp]

Posted by Neil Wyatt on 10/04/2018 16:12:48:

Looks like a BLDC motor as used on the Arc SC4.

Permanent magnet, 3 DC 'phases'.

Looks like many other 'Brushless DC' and 'Servo' motors but its probably not the Arc one as that is 1Kw (well over 1hp!) probably enough to twist the spindle!

The OP describes it as a permanent magnet AC motor so it could actually be a new 'PMAC' one as they seem to getting used in industry nowadays. I cannot find one online though that looks like the one in the video.

Improving lathes by putting motors on them is not exactly a new thing, I've even heard of people putting backgear on lathes that were never designed for it!

Ian P

[Neil WyattModerator @neilwyatt]

Posted by Ian P on 10/04/2018 17:44:54:

Posted by Neil Wyatt on 10/04/2018 16:12:48:

Looks like a BLDC motor as used on the Arc SC4.

Permanent magnet, 3 DC 'phases'.

probably not the Arc one as that is 1Kw (well over 1hp!) probably enough to twist the spindle!

I meant 'as used' in the generic BLDC sense

Neil

[Ian PParticipant @ianp]

Does anyone here know whether a typical VFD (say a Huanyang) could be used to power a brushless motor?

I have a 1.5HP servo motor which the label shows:240Vrms L-L, 3 phase, 0-200Hz, 4000rpm max, and 12A continuous rating.

I do have the matching servo control driver unit but that is in use driving another motor (currently on a linisher!) but I would like to put this spare motor to good use on my lathe.

Ian P

[MuzzerParticipant @muzzer]

Seems very proud of being able to develop full torque at zero rpm, somehow believing this is not possible on an induction motor. Clearly more pride than knowledge. If you really can't learn to remove the chuck key, you can get one with a spring on the shank.

Some VFDs have an encoder or resolver input (but not the Huanyangs) but TBH, for small motors you'd end up spending more on the drive than the rest of the system. Far simpler just to get a 400W servo drive from Aliexpress?

Murray

[Ian PParticipant @ianp]

Murray, a 400W drive is not going to suit a 2KW motor and because I have a spare VFD wondered whether it would drive this motor. I looked at the manual for the VFD in the video and it looks to be very ordinary and does not have any encoder inputs so I thought I was in with a chance.

I did once buy a VFD that I thought would work but it had a resolver rather than an encoder input, the cost of converting to an encoder input was more than a new VFD

Ian P

[VicParticipant @vic]

Posted by Hopper on 10/04/2018 10:10:44:

Neat. Great to see the old iron still being used in anger, with 21C tech.

Yes, agreed!

[Ady1Participant @ady1]

Very nice work

I would probably lose the chuck key 30 seconds after using it

Lost a 6 inch vernier 3 months ago while I was using it, god only knows where it's got to

6 inches of solid steel, completely vanished

[Alan CharlestonParticipant @alancharleston78882]

Hi Andrew,

Very interesting. Like everyone else I'd be interested in the motor and controller details.

Will the servo motor you're planning to drive the leadscrew with be linked to the headstock motor to allow screwcutting? If you can get that to work, then pretty much any knackered old lathe can be brought back to life with a bed grind.

Regards,

Alan

[John HaineParticipant @johnhaine32865]

a/k/a CNC…

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