By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by Allendale Jan 24th

CovMac Lathes

All Topics | Latest Posts

Search for:  in Thread Title in  
CHRISTOPHER MILLS 122/09/2014 08:05:53
avatar
152 forum posts
61 photos

Brian,

Here are the CovMac's back gears.back gears

Brian Wood22/09/2014 09:21:51
2187 forum posts
37 photos

Hello Phil and Chris,

Phil A busy man indeed, how do you find space to work with machines packed in as densely as that?!

Chris Another picture to ponder over, thank you. It is a bit hard really to make out details, but one thing you could confirm perhaps is that there is only one intermediate change wheel stud between the gear from the reverser cluster and the gearbox input.

I take it that what the picture shows is a partial view on a 30T gear from the cluster, there is another gear behind it which should be a duplicate of the gear size off the spindle, meshed with a 90T gear on the intermediate stud and that in turn is meshed with a 60T gear, the one with the spokes, using a smaller gear as a spacer. Is that the input shaft into the gearbox they are both mounted on?

Below all that seems to be a wilderness of spider webs and sundry rubbish.

This machine is gradually revealing itself rather as the dance of the 7 veils!

Brian

CHRISTOPHER MILLS 122/09/2014 10:09:51
avatar
152 forum posts
61 photos

Brian,

Thanks - Yes, the gearwheel with the spokes is mounted upon the shaft leading into the screw-cutting gearbox.

I am not sure what you mean by "intermediate change wheel stud"?

There are five wheels present in the picture.

I have removed the biggest, and dropped the banjo, to get at bolts holding the headstock on. The nut holding on the banjo is the largest on the machine - it is a real whopper, bigger than any of the Whitworth sockets we have to hand. I had to use a big monkey wrench.

The gears seem in really nice condition, and have been well lubricated all their lives, I think. I have a few spare gear wheels, also, but I do not think I have the metric conversion 127 t. That would be a really big one, if the big one in my picture is 90 t?

I will be interested to know more details on your view of the CovMac's screw-cutting gearbox as being "unusual".

As I begin to understand more, I am the more thrilled with this lathe. I had been watching lathes for 18 months, before taking the plunge with the one I really wanted - this CovMac.

I am also now beginning to sit with you, on leaving the carriage on the bed for the move. I think a 2 ton engine crane should easily cope with the 6 - 700lbs which I estimate bed, carriage and screw-cutting gearbox may altogether be.

So, I will only have to remove the headstock, and remove the plinth and legs from their concreting, and then we can move the beast.

What sort of lathe do you have, Brian?

Best.

Chris.

 

Edited By CHRISTOPHER MILLS 1 on 22/09/2014 10:12:00

Phil Whitley22/09/2014 10:11:49
avatar
1194 forum posts
145 photos

Hi Brian,

the only ones I use regularly are the Colchester and the Grafton Drill, When I have finished the workshop refurb (soon) all the machines will move to the other end of the shop into the "new" machine shop Then I will have "space"and probably grow a final front ear! I am embarrassed to post pics of it, but at the mo I am having a big tidy, and when that is finished, I will. I am actually very lucky because it is a big workshop which we originally built in the 1970's on half of a piece of land we paid £150 for!!! Them were't days!

Phil.

CHRISTOPHER MILLS 122/09/2014 10:15:18
avatar
152 forum posts
61 photos

Brian,

Sorry, I have the weight estimated wrongly. I think bed, gear-box and carriage may weigh about 1,000 lbs altogether.

The crane should be fine on its 1 ton setting.

Chris.

Brian Wood22/09/2014 11:01:48
2187 forum posts
37 photos

Hello Phil and Chris,

Phil Lucky you, I have a 1940's era chicken shed about 22 feet square with A frame roof timbers, 4 in all spanning the length, topped off with a corrugated asbestos/cement roof. To one side there is a lean-to section which adds a bay about 6 feet wide full length, but the roof is low there and it is all down to storage of one kind or another

The inner sanctum is a block built well insulated structure about the size of a single garage which I can heat. The outer workshop has a resident Tom Senior [the Junior model] horizontal mill and an Elliott 10 shaper.

The inner area houses a Myford ML7R with many modifications, a home built Dore Westbury vertical mill, also heavily modified from drawing spec. an old bench mounted Progress 1/2 inch bench drill [£25 in the mid 60's and yet more mods] and an Axminster 4.5 inch capacity metal cutting bandsaw. At the remote end is an old Graul tool and cutter , bench fitting, that I picked up at a BR auction in Darlington for £60. More modifications on that and I can 4 facet grind MT4 drills on it for when I had a part time job at a local agricutural engineers some years ago. Then I had access to a big DSG lathe and immense vertical mill with hudraulic drives, as well as a 50 tonne hydraulic press. I an still welcomed back but the DSG is now a Colchester Bantam

My interests lie in machine tools, not modelling, although I admire the workmanship and dedication that goes into those creations. Present projects include the Graham Meek screwcutting clutch/reverser drive which is in my view an inspired piece of work.

Chris The intermediate change wheel stud is just a name for the short carrier that holds the big wheel in your photo, there is room to fit two gears on it for a compound drive. More up to date lathes have two such studs, which add a great deal to the possiblities of the output from the screwcutting gearbox. As I think yours is arranged, there are few useful alternative arrangements and the results will be very limited.

The gearbox is unusual in that there isn't another choice of ratio change from A or B. The B choice halves the output from the box and gives finer pitch screwcutting. More modern lathes also have a C choice which gives x2 the output. The CovMac has to do that by swapping the gearing down from the headstock and it is all very manual since other useful arrangements do not have space left in which to set them..

Have a look around for spare wheels, there is one lying in the swarf tray under the gearbox. If you can find a 127T it will be a bonus; there should also be an 80T and a 40T to make up the set supplied. It wouldn't be hard to lose things like that in the general clutter.

If you can get a 2 tonne crane it would be much better suited to this job, a 1 tonne version. while badged as such, would I suspect be operating at close to full capacity even with the headstock removed and being built to a price it might struggle.

A word of caution If you are tempted to take off the headstock lid to see what's inside [I don't think that involves the spindle bearing caps at all] be careful not to lose the two slippers that will be on the inner ends of the lever arms that move the gear cluster and dog clutch. They could easily drop out and fall into the sump below. If that does happen, refit them with grease blobs holding them up on the levers to defeat the effects of gravity. It might be that they are secured, my Myford version is a loose push fit and can get lost under the gear cluster [don't ask!]

My description of how the headstock gearing works might fry the grey matter, but at least it is only logic---no maths there!

I look forward to further bulletins

Brian

CHRISTOPHER MILLS 122/09/2014 12:06:47
avatar
152 forum posts
61 photos

Hi Brian,

Thanks - I have found about six spare cogwheels, which I have saved. They are small and medium in size; one has a different centre diameter, and is welded to a smaller cog.

Yes, I will definitely get a 2 ton crane, they are little more expensive than 1 tonners. We have two main lifts to be done; firstly, taking it off its legs, and lowering it onto a pallet. The pallet will then be wheeled to the road, as access means the lathe has to exit the shed longways on. Thus I cannot carry it on the crane.

Then, we have to lift it, and the headstock, onto the trailer.

I am not worried by the archaic limitations of this machine's screw-cutting, for they will more than match my own!

I have one 'job' I would like to do with it, that is to make a turned component for a honey press box, which I am considering making commercially. Basically, it will be a turned drill type shank, with winding handle, to put pressure onto a wooden rammer, in a wooden box, to squeeze out honey from comb, and to melt and press beeswax, (I am a beekeeper).

We are due to remove it the first or second week in October.

I will record it well in pictures.

First part of renovation will be to rescue the four rusty chucks. I am going to build an electrolysis tank - it is an impressive methodology.

I will be removing screw-cutting gear box and carriage, when I have it safely in my own property.

I intend to restore to a reasonably good standard, and that will include deeply cleaning all of the components. I will not strip any inner workings, if it is all working correctly, but I want to flush out all swarf and debris and old oil.

On the headstock, I don't yet understand how the top levers 'move' the gear clusters, and I cannot imagine what these 'slippers' might be like.

I may not be able to resist taking off the lid, to see the main gears, but will try, as long as I can do a good 'flush out' of the headstock.

What about doing it with the headstock held on its side, to avoid these slippers falling into the sump?

Best.

Chris.

Brian Wood22/09/2014 14:12:02
2187 forum posts
37 photos

Hello Chris,

A brief reply as I am hedge cutting in the rare sunshine, more later on when I am done for the day.

I would not recommend laying the headstock on it's side; keep it upright so that any oliy crap in the bottom of the sump remains there. As for these slippers I mention, that position may even encourage drop out, much depends on their internal holding detail, a complete unknown at this stage.

I will if it helps send you a picture or two of that detail from my own Myford gearbox to help you understand what I am talking about.

PM me your personal email, I find it so much easier to send pictures that way.

More later

Brian

CHRISTOPHER MILLS 122/09/2014 14:30:49
avatar
152 forum posts
61 photos

Hi Brian,

I am out in the sun, too, feeding bees.

My email is cpmills1 "at" gmail "dot" com

How do I flush dirt out of the bottom of the sump?

Best.

Chris.

Frank.N Storm22/09/2014 16:36:21
48 forum posts
1 photos
Posted by CHRISTOPHER MILLS 1 on 22/09/2014 08:05:53:

Brian,

Here are the CovMac's back gears.


To help with our friend Chris' education in lathe things, these gears are not the back gear, but the screwcutting gears. Just to avoid any later misunderstanding wink

Regards, Frank

Brian Wood22/09/2014 17:14:49
2187 forum posts
37 photos

Hello Frank,

I read Chris's description with the right translation, but thanks for pointing it out. He has a steep learning curve ahead of him and having more or less assumed the role of mentor I feel I should see it through. Besides, being a bit of an old fossil myself, I have taken a distinct liking to this old survivor and want Chris to succeed in restoring it.

The alternative was probably the scrappy who would have cut it up with a torch, a very ignomious end,

Regards

Brian

CHRISTOPHER MILLS 122/09/2014 18:02:25
avatar
152 forum posts
61 photos

Frank,

Many thanks - where, and what are 'back gears', then?

I had imagined these were the back gears, because they were at the back of headstock.

I agree I have a steep learning curve ahead of me, but I want to get there.

Brian is right - without me, this poor, old Covmac was heading for the scrapyard.

Best.

Chris.

Phil Whitley22/09/2014 18:32:29
avatar
1194 forum posts
145 photos

Sorry chaps, only spent 5 minutes at the workshop today, was at home this morning, and spent the afternoon burning off, sanding and varnishing my mothers front door frame (did the door last week). She told me she had a go at sanding it down, but didn't like balancing on the stepladder to do it. Well, she is 84 after all, and she has made some concessions to her age, she only works at Cambrai covers mornings now ( unless she is going out on a measuring with my brother, which is usually a 6am start to anywhere in the country, and often get back after midnight) She fussed and made endless cups of tea whilst I cursed the paint and burnt my fingers on the hot air gun, but by 5-30 it was all done with the first coat on! I will go back tomorrow, put a second coat on, and then I WILL GO TO THE WORKSHOP!!!

Phil

Brian Wood22/09/2014 19:14:33
2187 forum posts
37 photos

Hello Chris,

I was just about to send to you, but the website thought differently and wiped the whole message, no hope of getting it back it seems.

As I am replying on a number of things I will explain back gears as well. They provide a further spindle speed reduction on the smaller hobby lathes and some others where the lowest spindle speeds generally available are just too fast for screwcutting or the machining of large diameter workpieces. With the range you have built into the headstock gearing, there is no need for this lathe to include that refinement. What you are short of are the higher speeds for turning smaller diameter work, the range is 23 rpm to 450 rpm in 8 steps and 450 rpm will not give a decent finish on stuff smaller than 3/4 inch or so in diameter. Horses for courses I'm afraid. This machine was built for larger work and would do that superbly.

As for flushing out the headstock, I have no ideas at this stage. A drain plug and fill level plug would both be useful, they might be hidden in the change wheel enclosure. I guess the headstock could hold as much as 2 gallons of oil; it will only be basic SAE 30 at most, modern technology oils and additives might not suit the bearing materials

I had to give up beekeeping years ago on medical advice after showing worrying signs of over-reaction to stings, the last one restricted my breathing and I was told it would need adrenalin and oxygen treatment to combat further exposure.

There is someting rather rewarding about working with bees with the sun on your back, I was really sorry to have to give them up. Today I get a similar level of satisfaction, in nice weather, from dry stone walling, a skill I have been developing for >25 years now.

In my time we extracted honey by spinning the combs., the empties went back to the bees to be cleaned up, a job they did with consummate ease. Beeswax went through a solar 'furnace' to both melt and bleach it so I am rather intrigued by your honey press concept.

The extra change wheels you have found. If you could list them in tooth count, including the doublet, I will see what other gearing possibilities I can come up with for screwcutting. Until you can free off the other selector, with the wheels I have seen, you are limited to 8-14 tpi inclusive as presently fitted. With the 60T and 30T swapped over the range is then confined to 2, 2.25, 2.5, 2.75, 3, 3.25, and 3.5 TPI; hardly the most useful in my opinion.

And while you are compiling that list, measure the diameter of one of them so that we can work out which Diametral Pitch [DP] they are to help search for future supply. The relationship linking those factors is DP = (N+2) divided by diameter in inches, where N= tooth count; it will be a whole number like 12,14 or 16 DP. The pressure angle for the gears of that vintage will be 14.5 degrees. The auction site ebay is a good place to look, but you need to know what specification is appropriate to match those you have; ie DP such and such PA 14.5 degrees. I won't burden you further with more than that, it is all part of gear technology..

Thanks for your email address, I'll take some pictures a little later this week to further your education. I have sent a test mail just to confirm contact at this stage, that way you can paste mine into your address book if you want to.

Best wishes for now, I have some washing up to do or face a bollocking when my wife gets back from Tai Chi, she is teaching tonight and the force will be with her!!

Brian

Brian Wood22/09/2014 19:19:40
2187 forum posts
37 photos

Hello Phil,

What a Mum, you must be proud of her. It doesn't sound to me like she makes much in the way of concession for herself, as they say 'Rock on'

No rush for the info, it just fills boxes at this stage in my understanding of this old machine.

I hope the weather is fit for you tomorrow, I expect rain up here in North Yorkshire.

Best wishes

Brian

Phil Whitley22/09/2014 19:46:58
avatar
1194 forum posts
145 photos

Hi Brian, I am in Driffield, where are you in North Yorks?

Phil

Brian Wood23/09/2014 08:52:59
2187 forum posts
37 photos

Hello Phil,

Just outside Thirsk, the up to date forecast suggests late morning arrival of rain, heading your way for later.

Brian

Phil Whitley23/09/2014 19:47:23
avatar
1194 forum posts
145 photos

Hi Guys, here are the pics as promised, Chris, top and bottom view of the oil cap from the main bearings, Brian pics showing the position markings on the screwcutting gearbox. Looking at pic 5 it looks like the cover will come off without disturbing the bearings.( I think this is what you wanted, if not ask away) I got the Varnish on, rain arrived early evening as you predicted. Probably at the shop tomorrow, then again friday, Thursday it's back to Jims as he has screwed his central heating, and I have to fix it, so if I am good, and it doesn't take all day, we might get a play in his workshop.

Phil

CHRISTOPHER MILLS 123/09/2014 19:57:37
avatar
152 forum posts
61 photos

Phil,

Smashing - many thanks for all of this. I am missing at least one of these main bearing oilers, definitely.

On the main spindle, where it exits the headstock, before the spindle threads, there is a substantial brass collar, which looks as if it is in two halves - are these the actual main bearing shells?

It might seem that replacing CovMac spindle bearings might be at least a job easily accessed, if need be?

Best.

Chris.

 

 

Edited By CHRISTOPHER MILLS 1 on 23/09/2014 19:58:17

Edited By CHRISTOPHER MILLS 1 on 23/09/2014 19:58:51

Phil Whitley23/09/2014 20:49:18
avatar
1194 forum posts
145 photos

Hi Chris, Yes they are the spindle bearings, they will be some sort of bearing bronze. Yes very easy to replace, but quite a bit harder to scrape to size and get the spindle running right. The great thing about these machines is that you can make most of the parts that wear out in a basic machine shop.

Phil

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Latest Forum Posts
Support Our Partners
ChesterUK
Warco
cowells
Allendale Electronics
emcomachinetools
Eccentric July 5 2018
Eccentric Engineering
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest