New Project Atlas Bearing Replacement

Have a word with Mike Kurn (formerly of Acorn Tools, one of the UK manufacturers of Atlas clones), tel. 01784 434225. He keeps a wide range of spares for these lathes and can source others from the US. Always willing to offer advice as well.

Russell.

Have you considered remetalling the bearings and remachining them? It can be done in a similar manner to the way a plumber would do a "wiped" lead joint.

Hi There, There is a book offered by camden books that tells you how to do your own babbit bearings and if i remember correctly is quite simple. Either that or make your own bush and hand scrape it to size seems you have other lathes available. Hope this helps Colin Heath

Babbitt metal is only about 25 to 30 brinell. You are right in thinking that Bronze or CuPb bushes will wear an unardened shaft. Duralumin is similar hardness and will also wear the shaft. Babbitting is simple as a set of basic steps, but that does not mean easy. It takes practice and good control of temperatures. For correct babbitting methods you can look at the info I put on

For a really cheap bodge, if the bearings are only worn a little, you could try depositing a layer of solder on top of the babbitt and then cutting it back to size. Solder is softer than babbitt, but is similar to the flash coating you get on some bronze and aluminium bearings. If you are only taking up a few thou of wear you might get away with it. It will not damage the shaft and if you have plenty of time but no cash it might give you some service life. From a professional standpoint it is a terrible bodge. Good luck. Phil

Phil, thanks a great site and some really useful information. I have tried a little Babbiting before and as you say have found it very difficult. With a normal welding torch for a heat source I found it difficult to control temps and had some problem with getting the material to "stick" to cast iron. Pity I didn't do this research before I took early retirement as I would have had access to some very capable ovens then. I'm interested in your "terrible bodge" of course as I do indeed "have plenty of time but no cash". Any thoughts on suitable Babbitt preparation, flux and solder? The bearing has been "butchered" (previous to me - honest) to try and improve oil flow so maybe i could fill these in as well.

After some more investigation I see that the lower Babbitt is in fact breaking away from the headstock casting, looks to be a .004-.006 gap here but I suppose I could back it up with some suitable shim stock to provide support.

Phil if hardness is the issue how about some normal soft Aluminium, or will that "pick up" when running.

Anyway thanks for your ideas I certainly have more to ponder now. Thanks also to Russell and Colin for places to look for more information and of course to Briano who also suggests re-metalling. I think I might just give it a go.

Best regards

Keith

If the shaft is unhardened (Brinell less than 200) there are only two ideal materials. The original babbit and aluminium containing at least 20% tin. However bear in mind that wear is a gradual process and if the machine is not going to get much use then a theoretically non-ideal material such as bronze isn't going to cause a major problem. There's a hell of a difference between something that needs to be used at full capacity 8 hours a day, 5 days a week and a machine that's only going to get switched on once in a blue moon.

With that in mind I think you could also consider a leaded bronze which is much more suitable for unhardened shafts than tin or phosphor bronzes. In fact taking this pragmatism to its extreme you could say that a few hours of use a year isn't going to be equivalent to even a month of full time industrial use for the rest of the machine's lifetime and that any material that falls conveniently to hand will do the job. The owner will probably die long before the shaft or new bearing do.

Your other option is to hard chrome or tuftride the shaft which will let you use just about any bearing material you can find.

Dave, thanks some great thoughts there which certainly increase my confidence no end. I have several pieces of "dubious" bronze that would do the job (in size anyway), but they range from a very yellow colour (not as yellow as brass) through the more normal "bronze" to one that has an almost blue tinge. Does the colour give any idea as to the composition of the material? Would I be better getting the hardness tested or is there another way to "roughly" identify bronzes. I also have some very soft Aluminium so perhaps I should machine a couple of short test bushes and run some mild steel bar in them for a couple of days and see the result. I assume that a "leaded" bronze will machine better than "tin" so perhaps I will just go with the best machining bit I have.

I think I will try re-metalling the current bearings as a trial and then if I b***"*ks that up (highly likely) then I have the safety net of your suggestions. As you quite rightly point out the usage my friend is likely to put the machine to in the next 10 years would not equate to a months running in "proper" use. As I will need to re-bore and scrape in all options any idea what size I should bore as a start before scraping - shaft size plus .001"?

Thanks to all for your replies and suggestions, I now have a way forward that allows for at least one "co*k up" without it being totally unrecoverable. Happily it also appears that the cost might not dig too deeply either. Ah well, enthusiasm topped up, Monday tomorrow, wife going back to work, machines oiled, empty and waiting; what more could I ask for. Retirement is not all bad.

Regards

Keith

I understand the thought process. I've been down the same route a dozen times trying to identify the "optimum" bearing material for race engine components such as valve guides and conrod bushes. You chat to all the supposed experts, including in my case Cosworth and similar, and find they all have different views and half the time the material they select is because of cost or ease of machining rather than suitability for purpose. In the end you generally decide that using whatever you have to hand will do the job well enough. The charts you get from bearing material suppliers showing suitability for use with hardened or unhardened shafts, good and bad lubrication, alignment etc are designed for long term heavy duty usage and probably have little applicability for occasional home shop use.

I have several pieces of "dubious" bronze that would

I'm colour blind so not the best person to ask about grading materials on that basis :)

Would I be better getting the hardness

Any ally you have lying about is vanishingly unlikely to be high tin content bearing grade aluminium. Normal cast and forged grades of aluminium, if well lubricated, make adequate bearings on hardened or chromed shafts but tend to gall against soft ones.

I assume that a "leaded" bronze will machine

Leaded does machine easily compared to right sods such as aluminium bronze so it might give you a guide but nothing definitive.

I'd machine to the nominal size of whatever clearance you are aiming for to start with. Scraping is only going to remove tiny high spots and you don't want to be removing thou's of material that way. 1 thou per inch of shaft diameter is a decent guide to clearance on plain bearings in engines with pumped oil supply but I'm no expert on that subject for machine tool bearings. I'd probably go as tight as you can because the hydrodynamic wedge lubrication isn't going to be able to fill a large gap on a low speed shaft with unpumped lubrication.

I'd bear one final point in mind. Machines, whether engines or machine tools, have very exact specs laid down by their designers but seem to soldier on regardless if things are worn or badly made from new. Whatever you finally decide on is going to be a thousand times better than the shagged bearings it has at present and will no doubt be perfectly serviceable whatever you make it from or what clearance you choose. I wouldn't lose too much sleep over it all. Keep us posted about progress though and if there's any more help we can offer....

How much would a couple of pounds of whitemetal cost for Keith to machine into bearing shells from solid (or approximate castings) rather than trying to re-metal the existing bearings? I assume that this would hold no fears for him since it would be an easier job than doing the same thing with any bronze.

Mark Rand RTFM

Dave/Mark

An update (crisis) even before the job has started. Armed with great enthusiasm I was up early (for me) and as soon as the wife was out the door I was in the garage and away, or so I thought. My crisis is that when looking at the current settup the Babbitt was obviously poured into the casting and then bored, it does not appear to be machined half shells as I expected (don't forget I am aircraft based not machine tools). I then had a sudden thought that the headstock casting may not be that accurately machined and in using half shells of any material could in effect move the centre of the bearing even if the casting has been bored to provide a reasonable seating for the shells. End result is that I'm back here "thinking" rather than "doing" as I should be. I'm about to have a look to see if I have room to set the headstock up on my small mill to bore out if needs be.

It then struck me that if I needed to bore the headstock casting anyway, why not bore it to take roller bearings? I would need to "pin" and fix the top half of the casting but that doesn't look too difficult

- famous last words?

Mark, Babbitt seems very expensive but when thinking about your idea I realised that I already have 80% of my needs anyway, assuming of course that this can be melted and reused. I know that would result in a "blend" but as Dave says close enough is good enough. I think like Fred and his piano I will have another cup of tea before I go and knock another wall down. Apologies to younger readers but your education is sorely lacking if you haven't heard about Fred and his piano.

Best regards

Keith

So if we _have_ heard of Fred's piano, you're calling us old, right ?

-adrian

Adrian

No not really, only as old as I call myself, and I still feel young (sometimes). It might be more of a "slight" to your (or your parents) taste in music!

Regards

Keith

Veritably antiquated methinks.

Right said Fred Both of us together One each end and steady as we go

Tried to shift it Couldn't even lift it We was getting nowhere And so We Had a cup of tea and

Right said Fred Give a shout to Charlie Up comes Charlie from the floor below

After straining Heaving and complaining We was getting nowhere And so We Had a cup of tea and

Charlie had a think and he thought we ought To take off all the handles And the things wot held the candles But it did no good Well I never thought it would

Oh Right said Fred Have to take the feet off To get them feet off wouldn't take a mo

Took its feet off Even took the seat off Should have got us somewhere but no! So Fred said let's have another cup of tea And we said Right-o

Oh Right said Fred Have to take the door off Need more space to shift the so-and-so

Had bad twinges Taking off the hinges And it got us nowhere And so We Had a cup of tea and

Right said Fred Have to take the wall down That there wall is gonna have to go

Took the wall down Even with it all down We was getting nowhere And so We Had a cup of tea and

Charlie had a think and he said look Fred I've got a sort of feeling If we remove the ceiling With a rope or two We could drop the blighter through

Oh Right said Fred Climbing up a ladder With his crowbar gave a mighty blow

Was he in trouble Half a ton of rubble Landed on the top of his dome! So Charlie and me had another cup of tea And then we Went home

Another suggestion might be to remetal and bore the new bearings in-situ. Have a look at Dave Gingery's book (ISBN 1878087010) for ideas. Especially as you already have a spindle in the lathe, at centre height, you could set up a couple of blocks on the cross slide, line bore them to a convenient size (before you pull the machine to bits), and rig up a temporary boring bar for the newly-Babbited headstock.

Hope this gives food for thought.

John, thanks excellent idea. I had put things on hold for a little "thinking time" as I always like to have a couple of fall back positions if things go wrong (regularly with me) and I found today that I can't get sufficient height on my little RF25 mill to bore the headstock casting. It has insufficient spindle travel and of course being round column is a pig to maintain register if you need to reposition the head. If I bore a couple of blocks out to take my 1" boring bar then I should be able to line bore in situ at the correct centre height. As you say, I can use this for any of the options for the headstock bearing repair.

I spent the afternoon looking for some suitable roller bearings to see if I could replace the plain Babbitt, but the only ones I have that are the correct internal diameter for the spindle, would leave little cast iron on the caps to provide support as the outer diameter is quite large. I will stay with plain bearings I think.

So with enthusiasm nearly back to what it was this morning I'll try again tomorrow. That's if I can get that Fred and his piano song out of my head now that Dave has provided all of the words for me. Thanks to all for the excellent suggestions that have averted another minor crisis in my progress. I don't know what else you could expect from this forum; superb ideas, some good humour, musical interludes and cracking advice. Who needs the idiot box; wonder what the cheese is like Grommit?

Best regards

Keith

Keith, You need to mark a register on the casting before you melt out the babbitt so you can make a true centred bore after casting new babbit. If the old babbitt is in good nick, you could add about 25% of tinmans solder to make up the quantity without losing more than about 4 or 5 points Brinell hardness. The chances of buying a small quantity of babbitt are very slim - when our company policy alowed the sale of a 3 kg bar it was over 50 quid ex works. You might find a garage that has a bit they are willing to sell left over from old engine days. To fit roller bearings could throw a strain on other bits - they are not so forgiving as babbit bearings if misalignment is an issue. Finally - if you go for casting the babbitt into the housing, as it is at present, you need to tin the housing first and cast the babbitt on to the molten tinned surface to get a good bond. Alternatively you could make the babbitt into half shells and 'araldite' them in. If you do that, an anti-rotation key or peg needs to be added for security. Phil

Sounds like a pretty complex job compared to making a bronze bush and pressing it into place.

I have a few other thoughts which may or may not be of help depending on how the headstock is constructed.

1) If white metal shell bearings could be used then there's a good chance that there'll be something out there that fits from an automotive engine if the lathe shaft is a std size. I have the Glacier catalogue which lists the shaft size, housing o/d and bearing clearance for pretty much every engine ever sold in the UK. The clearance can be tweaked by filing the edges of the shells down a tad before fitting them. 2) In the USA they often repair the rear flange of crankshafts that the oil seal runs on by machining it down and shrinking on a thin wall hardened repair bush. Perhaps the same technique could be used here to adapt the shaft to a different bearing size and also properly suit a bronze bearing. This would eliminate any existing wear in the shaft as well. 3) On modern engines the camshafts usually run directly in the aluminium of the cylinder head and very little wear takes place on either item. High silicon aluminium is a decent bearing material for cast iron or steel shafts. I have a load of old cylinder heads knocking around which might provide the parent material for a bush to be made out of. It would help if I knew the shaft size we're talking about here.

If Hoyt don't sell small (3-5kg) quantities of Babbitt any more, Who does? Out of curiosity, is this a minimum order thing, or some other reason?

Mark Rand RTFM

Phil/Dave

Sorry for the delay in replying but "normal life" has again got in the way of enjoyment so I haven't been in the garage for a couple of days. Phil I have a couple of large bars of "solder" that I cleared from my fathers shed when he moved so I could dilute the remains of the Babbitt with that. Not sure if the original is in good nick though as it does seem to have a few "inclusions" that have been lapped into the bearing. I can machine that away but I suppose that will increase the dilution a bit.

Dave, the spindle is a nominal 1.5" OD but it has worn over the area of the front bearing and is now 1.494" and tapers slightly so will need re-surfacing to a slightly smaller size anyway. Thinking about various alternatives as you suggest, I had thought of trying some fairly thin two row ball bearings on the front with a little pre-load provided by a thrust washer against the rear face of the rear bearing which appears to be in reasonable condition. However this will require a sleeve to overcome the spindle wear and I'm not sure if it would be any better (easier) than a plain bearing.

Confession Time. I must admit that you have all convinced me that this could be done with a reasonable chance of success but, and there is always a but, I am not at all confident that I could make a worthwhile job of it. In the end I have given my friend a nearly brand new Emco Compact 8 that I was using for a bit of wood turning. He is over the moon and I am left with the problem of what to do with the Atlas. I certainly don't need it or want it. I suppose that someone might use the parts if I put it on the dreaded E-bay. On the other hand, I hate being beaten (or in this case giving up) if something is repairable and I suffer from this "engineering" affliction of "if it can be repaired it should be". Incurable I suppose. Having sorted the immediate problem of providing something for my friend, I guess the Atlas will go back under the bench waiting for that rainy day when I have plenty of time and am looking for an interesting project. Are we all the same?

Anyway, thanks to all for the suggestions I'm sure that many of them would have produced a very usable lathe. Apologies for not implementing them but I now know what to do just need to find the time to do it.

Regards

Keith