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CovMac Lathes

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john fletcher 102/10/2016 12:53:22
572 forum posts

Hello Phil and many others. This has been a very interesting read regarding both lathe and the motor. You are correct Phil re the 440/480 volt motors, there were quite a few in the Scarborough area. I think the pole mounted transformer were know as the Scott connected type. 11KV input and 440/480 two or single phase or call what you will out. If you have access to JOHNSON & PHILLIPS transformer book there is an explanation on the transformer side of things.John

Phil Whitley02/10/2016 13:28:31
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1060 forum posts
137 photos

Interesting John Fletcher, now you mention it, I remember a, installation on a farm at Broxa, out on the moors near Scarborough, which I think was split phase, and to tie right back to Covmac, my Covmac came from Andrews motorcycles in Scarborough!

Phil

john fletcher 102/10/2016 19:48:39
572 forum posts

Hello Phil, there was a lot of split phase around Cloughton and Ravenscar. and on the farms up in the Whitby direction The Duchy of Lancaster saw mill was split phase. You could see the small unusual pole mounted transformer, with 11KV input, that was in the days of YEB and NEEB of course. OK about Andrew's, motor bike shop, we have bought several Honda 90 from them when Nick was the owner. Changed hands about 5 years ago when you bought your lathe from, can't remember his name, Dave Whittaker! . The lathe saga has been very interesting. Its good when people help each other out and share experiences.John

Phil Whitley03/10/2016 20:39:17
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1060 forum posts
137 photos

I bought the lathe from Nick Andrews who was in the process of transferring the business to some other guys, Nick had a lot of other engineering gear of his dads(?) which he was goning to get back to me about, but I lost touch with him and it never happened, Also bought a B&D valve refacing machine from him, it was in poor condition, with some bits missing, but I am still thinking about converting it to grind lathe tools, if it works! It is a winter project which may get done this winter as my massive workshop rebuild is almost finished!

Phil

CHRISTOPHER MILLS 104/10/2016 06:08:47
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152 forum posts
61 photos

Phil,

I have just noticed, or recalled, that the top speed of our CovMac 13" lathes is just a chugging 335 rpm?

What are the limitations of such a modest top speed?

It compares badly to my Lang Junior, a similar sized machine, which will go nearly 1000 rpm.

What work can we do with these go-slow CovMacs, when we have them running?

Chris

Brian Wood04/10/2016 08:21:20
2072 forum posts
37 photos

Hello Chris,

​If you still have the Holbrook gearbox, I'm pretty sure that could be built into the drive chain somewhere between the motor and lathe to double the speed as required for those occasions when it is needed.

A little ingenuity is about all it takes. I can't believe the lathe itself couldn't handle that

Brian

Phil Whitley04/10/2016 10:02:33
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1060 forum posts
137 photos

Hi Chris and Woody,

The limitations are not that important really, as we are not manufacturing hundreds of identical parts at piece rate! the only real problem and it can be got round, is turning to a fine finish. The usual way to get this is high speed, fine traverse feed and a light cut. All you need to do is work within the limitations of the machine, and you will get approximately the same finish, but it will take marginally longer! When running a machine faster than its design speed, you have to consider that these lathes have plain bearings, which would need greatly increased lubrication, maybe in the form of a drip oiler, and also the condition and weight of the chucks and faceplates. My faceplate has so many blowholes in the casting that I don't even think I would risk it at 335rpm! The forces on a lump of poorly balanced cast iron at 335 rpm are considerable. Therew are stories of overspeeded chucks bursting with centrifugal force, whilst I have no experience of this, I would not wish to be in the same building when it happened! These lathes were used during wartime, and I am sure they managed to produce components adequate for the very demanding tasks required. Don't worry about it untill it becomes a problem, and if it does, you can always step across the workshop to a different lathe Part of the fun of engineering is thinking of inventive ways round the problems we are faced with!

Ian S C04/10/2016 10:49:49
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7468 forum posts
230 photos

HSS tools, a good size chunk of steel, and a good depth of cut and 335 rpm, it will remove quite a good amount of metal with a good finish, it's not made for watch making, it would be happier with a 6" bar of steel in the chuck.

Ian S C

Phil Whitley04/10/2016 18:24:36
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1060 forum posts
137 photos

+1 wot Ian SC said!!

CHRISTOPHER MILLS 104/10/2016 23:41:13
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152 forum posts
61 photos

Sorry, chaps - I have been in error - reading relevant gearbox information plate on the machine, I see top speed for a 13" geared head CovMac is actually 450 rpm, not 335.

Chris

Phil Whitley05/10/2016 08:48:16
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1060 forum posts
137 photos

Gospel according to Tony, Chapter 6 verse 3 says the 445 rpm top speed is on the belt drive (conehead) model, but they may have been later mods as both ours are much later models than the one illustrated on tony's page. I will check mine today and see what it says on the plate.

Phil

Brian Wood05/10/2016 09:30:45
2072 forum posts
37 photos

Hello Phil,

​The 17 inch model at Leicester currently for sale on eBay has a top spindle speed of 450 rom, from a pulley speed of 320 rpm, that is the same as you will have

The data plate for the gearbox has been added in response to a request and it makes interesting comparison when compared to that fitted on your lathe and Chris's-----there are subtle differences throughout the speed range. The gearbox however will have identical internal gearing to deliver the outputs it does, despite the rearrangement of the external levers. It makes little sense to me to do that, why change? It costs money to change such things, there must have been a reason but it escapes me entirely.

​Brian

 

Edited By Brian Wood on 05/10/2016 09:31:29

Phil Whitley05/10/2016 21:30:31
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1060 forum posts
137 photos

Hi Woody, needless to say, I forgot, been very busy putting the last sheets on the new roof, will look at mine tomorrow!

Phil

Phil Whitley20/06/2018 20:23:27
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1060 forum posts
137 photos

At long last the Covmac leaves its dusty lair, and enters the main workshop, through a door that didnt even exist when it went in there! First job was a thorough clean, and tomorrow I will move it into its new home, and reassemble it. I have decided on a three phase motor, as the repulsion induction variable speed single phase one that came off it is so huge and heavy I doubt I would be able to hoist it up at an angle to refit it without turning the whole plot over and probably having an accident. BTW, it isn't two tone, the whiter brighter bits are in natural light from the door, whils the yellow bits are under fluorescent lights.

CHRISTOPHER MILLS 120/06/2018 20:33:56
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152 forum posts
61 photos

Phil,

Fantastic to see it!!

You have beaten me wholesale

Best

Chris

Phil Whitley20/06/2018 20:41:10
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1060 forum posts
137 photos

I only got it out of there yesterday, and cleaned it todayI will post a few more pics after tomorrows fun! The engine crane is only there in a supporting role, it will lift it (just) but it is mainly to prevent toppling, and to help with my nerves, it is a heavy brute.Good to hear from you again Cris!

Phil

Brian Wood21/06/2018 10:25:03
2072 forum posts
37 photos

Hello Phil,

Nice to see the old Covmac coming back into daylight again. Looking at the lathe again after this break in time it is still a very businesslike piece of machiinery and made to last, thank you for reminding us what it looks like.

And nice too to hear from Chris again, I thought you had disappeared into a trench in the marshes in Kent!

By the way, you may not remember but tomorrow is the first anniversary of our joint rescue of your old Hendey lathe from that farm workshop at Ellington near York

Best wishes to you both

Woody

john fletcher 121/06/2018 12:32:12
572 forum posts

Hello Brian,Phil and Chris. Phil and Brian in particular being sort of local Have you ever thought of joining PEEMS at Pickering, a mens metal working club in its broadest sense. In November we have a talk on the Field Marshal tractor later we have CUP Alloys talking about Silver Soldering, later still, a talk on a home built aeroplane. We had a good visit to JCB factory and to ARC at Leicester. John

Brian Wood21/06/2018 14:03:45
2072 forum posts
37 photos

Hello John,

Some 35 years ago I had major surgery on my right eye , twice, to re-attach the retina, having had cataract surgery beforehand. Ever since then I have struggled with driving in poor light conditions with the damaged vision from that eye and eventually ceased night driving voluntarily.

Getting to and from Pickering from my home on the outskirts of Thirsk is fine in daylight, but not on for me in the darker months so for that and other reasons I have been a freelance operator and not affiliated to any club.

Thank you though for the invitation. I can't speak for Phil but Chris is London based so it is hardly practical for him

Kind regards

Brian

john fletcher 121/06/2018 16:48:09
572 forum posts

OK Brian well that is understandable. I don't like driving at night either and so get a lift with a friend. to club meetings . I don't like those modern blueish head lights to much glare. Members come from far and wide, not every member turns up at every meeting, nor do I for that matter. John

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