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Motor for ML7

replacement needed

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ken king, King Design01/05/2021 17:13:59
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144 forum posts
239 photos

Help ! The Metro-Vickers motor, type BS 2408, 1/3 hp, 1425 rpm, of my old ML7 has just gone phut. Initially it developed a dead spot and would not start unless rotated a 1/4 turn or so. Now it just buzzes at me or creeps round at extremely slow speed.

Any suggestions for sourcing a reasonably priced replacement will be hugely appreciated, or if you have a suitable motor spare please let me know so we can discuss price etc.

Thanks,

Ken

Andrew Tinsley01/05/2021 18:13:38
1514 forum posts

I assume it is single phase? It sounds as if the capacitor is faulty, if it is a capacitor start motor. Worth checking as a capacitor will be under £5, rather cheaper than a new motor.

Andrew

Grindstone Cowboy01/05/2021 18:24:28
799 forum posts
62 photos

I have a ML7 that has had a Machine Mart motor fitted. I'll just go and see what model, it still has the sticker on it. Guard had been modified to fit it though (but not a major job and it still covers the rotating bits unless you go and stick your hand somewhere silly) and extra holes were drilled in the mounting plate, although I think it could have been made to fit the existing holes if whoever did it had tried a bit harder

Rob

Mike Poole01/05/2021 18:40:48
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Moderator
3162 forum posts
72 photos

If the motor has failed and replacement caps and the centrifugal switch if fitted do not respond to TLC and replacement then it may be time to consider whether a VFD would be a good route to go down. If a replacement motor to give the same manual speed change facility is all that is required then motors are available, direct replacement motors with an imperial shaft tend to be a bit dear but a 3 phase motor and inverter package will cost more but the usability improvement is almost universally recommended.

Mike

Grindstone Cowboy01/05/2021 18:55:33
799 forum posts
62 photos

Well that was reminiscent of another thread - having taken the motor off the lathe a couple of months ago so I could strip and repaint the lathe, it took me twenty minutes to find it again! Anyway, here are some photos of the modified guard and the Clarke motor.

img_3949.jpg

img_3948.jpg

img_3947.jpg

Looking at the price, not sure how long ago that motor was fitted!

Rob

duncan webster01/05/2021 19:02:46
3706 forum posts
69 photos

I ran an ml7 for many years with a 1/4 hp motor. It's not a lathe for big cuts, but it would happily take 40 thou deep

ken king, King Design02/05/2021 23:57:10
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144 forum posts
239 photos

Rob, thanks for going to so much trouble. It's a single phase non-capacitor motor, and as I had nothing to lose I took one end off and cleaned up the centrifugal switch contacts and ring, (thanks for the tip Mike) and blew all the swarf out, at which point didn't my wee compressor give up the ghost with a dribble of smoke ? Gremlins are swarming, so look out !

Reassembly is under way, sufficiently advanced to say the motor runs again, but not yet fully integrated into lathe so unsure about revs being achieved, but looking much better, thanks to all.

ken king, King Design05/05/2021 09:46:57
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144 forum posts
239 photos

Hmm ... situation unchanged apparently. There is still a dead spot requiring some hand rotation to get going, but for the moment I can use the lathe on that basis to clear a job. Do the symptoms suggest a dead field winding perhaps (my understanding is sketchy) and if so is it practical to consider repair rather than replacement ?

John Haine05/05/2021 09:59:04
4420 forum posts
262 photos

Metrovicks became part of AEI sometime in the 1950s though I think the brand was still used on heavy machinery for some years. My father was a graduate apprentice at MV in the 30s and worked there in early wartime! Your motor will be 50 years old or more.

I think the motor deserves a leisurely retirement and its role being taken over by something to a more modern spec. As it happens I have a cap start induction motor from a VMB (to which I fitted a 3-phase motor) gathering dust. It has a 3/4 shaft if that would fit your pulleys? Let me know if interesting.

Trevor Drabble05/05/2021 11:46:45
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271 forum posts
5 photos

Ken , I also have a Brooke motor available , complete with a new quality start/stop/reverse switch , which was removed from my recon S7 shortly after l bought it from Myford Nottingham in order to fit a Newton Tesla VFD assembly . If you're interested , can email you pics . Trevor .

ken king, King Design06/05/2021 15:13:36
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144 forum posts
239 photos

What helpful chaps you all are, thank you. Trevor, I've sent you a message,

Regards,

Ken

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