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Vintage lathe meets 21st Century

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Andrew Davies 410/04/2018 08:03:54
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49 forum posts
56 photos

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
Hopper10/04/2018 10:10:44
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3709 forum posts
73 photos

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

Brian Wood10/04/2018 10:24:58
1966 forum posts
37 photos

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

Daniel10/04/2018 10:53:09
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249 forum posts
39 photos

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 !!

starstarstar

not done it yet10/04/2018 10:59:35
3358 forum posts
11 photos

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 310/04/2018 11:36:44
94 forum posts
17 photos

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 P10/04/2018 11:44:05
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2175 forum posts
90 photos

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

richardandtracy10/04/2018 12:02:01
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938 forum posts
10 photos
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 P10/04/2018 12:46:25
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2175 forum posts
90 photos

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 Haine10/04/2018 15:04:02
2608 forum posts
133 photos

This link might help with the motor.

MW10/04/2018 15:12:48
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2050 forum posts
51 photos

This is the Video;

Michael W

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

Ian P10/04/2018 15:23:52
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2175 forum posts
90 photos
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 Wyatt10/04/2018 16:12:48
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Moderator
16568 forum posts
687 photos
75 articles

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

Permanent magnet, 3 DC 'phases'.

Jon Cameron10/04/2018 17:09:46
228 forum posts
87 photos

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 Haine10/04/2018 17:38:36
2608 forum posts
133 photos

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 P10/04/2018 17:44:54
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2175 forum posts
90 photos
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 Wyatt10/04/2018 18:01:22
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Moderator
16568 forum posts
687 photos
75 articles
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 P10/04/2018 18:56:28
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2175 forum posts
90 photos

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

Muzzer10/04/2018 19:33:34
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2904 forum posts
448 photos

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 P10/04/2018 20:00:02
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2175 forum posts
90 photos

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

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