|noel shelley||20/12/2020 12:43:14|
|390 forum posts|
Gentlemen, There are 100s of ML7s being used but no new original headstock bearings, only an expensive conversion kit. WHY is nobody making them ? Is it that there is no market or is there some hidden pit fall ? I am considering setting up to cast these white metal bearings in sets with new shims. An alternative might be to remetal as with old type big ends. The plan as it stands would be to use a redundant headstock and machine up an undersize mandrel to enable the oil ways to be cast in. This would be reamed under size allowing the owner to either scrape to size or allow bedding in and subsequent removal of shims as needed. BEFORE I waste alot of time on this idea I would appreciate any suggestions or comments. Noel.
|roy entwistle||20/12/2020 13:42:05|
|1319 forum posts|
Noel Can I ask where you are based ?
|duncan webster||20/12/2020 14:11:45|
3070 forum posts
I've read somewhere that ML7 bearings were bronze with a very thin white metal coating, like automotive crankshaft bearings, but I've also read of people scraping the bearings, which implies a greater white metal thickness. Anyone know for sure?
I've tried looking at the lathes.co.uk site, but my browser thinks it s a security risk and discourages e from going there.
I'm possibly one of the few who have actually re-metalled white metal bearings. With a modern non contact pyrometer (not expensive) it wouldn't be too difficult, we had to mess about dipping pine sticks into molten metal (if it chars it's hot enough) and preheating the bronze using Temple sticks, a sort of wax crayon that melted at the right temperature.
|Rod Renshaw||20/12/2020 14:29:19|
|244 forum posts|
My old ML7 has white metal bearings. I don't remember any trace of bronze colour when I last dismantled the headstock.
|Brian Wood||20/12/2020 15:31:29|
|2341 forum posts|
Your idea is laudable but I rather fear it could founder very badly on the sheer economics of production, purchase of the correct grade of white metal to make up for losses and other such production costs. How would you price them, very difficult in today's value driven and competitive day.
Then you have to tell the world these new bearings are available which means constant and expensive advertising to keep the product visible, postage to distant parts etc etc quite apart from the problems of dealing with those who think they know how to scrape them in but wreck the bearings in so doing and come to you with complaints.
I'm sorry to paint such a gloomy picture but I think the market has moved on so far since those days and in spite of your enthusiasm, maybe there is only a very limited market you could tap into still in existence
Certainly not a money making idea, rather the opposite
4235 forum posts
Once you get the skills there's quite a few lathe owners would be interested methinks
Advertising nowadays is a doddle, ebay and amazon give you a global reach... and you only pay them if you make a sale
"This product is a consumable. No returns"
and send in a sealed bag for anyone who buys it in error
Edited By Ady1 on 20/12/2020 17:59:58
|198 forum posts|
Another who thinks that it's an interesting project, but has serious misgivings as to whether it's viable - as user observations/perceptions rather than expert opinion;
In general, the bearings seem to outlast the usefulness of beds, saddles, and tailstocks - the cost of refurbishing these is commonly commented on & baulked at by all but the most determined restorer.
I think the most problematic difficulty is that you will be sending out an expensive 'raw material' that relies on the customer's ability to hand fit and scrape them to the level of a time-served craftsman for success - (It wouldn't surprise me at all to find that this WAS the reason for their original discontinuation) - one can imagine who will be to blame when it doesn't go well..
It might be a more realistic business proposition to practice the whole process until you have the perfect job down pat, and then offer the complete bearing refurbishment service from start to finish yourself.. ..people did (and do) make money from such things as magneto refurbishment & instrument repair on this basis..
|R Johns||20/12/2020 18:32:37|
|38 forum posts|
I would be in as well if white metal bearings were available.
|Jon Lawes||20/12/2020 18:38:39|
472 forum posts
Maybe you could even sell them via Myford themselves.
One point to consider, These are unlikely to be repeat customers. Your new bearings will probably outlast the person who fits them.
|Howard Lewis||20/12/2020 19:29:55|
|4455 forum posts|
Is it that the bearings are badly scored, or that that things could be restored by removing some of the laminated shim between each cap and the Headstock? If this is possible, the bearings would probably need to be scraped in to match the shaft. This would be time consuming, but avoid the problem of finding new bearings, or the cost of having the current ones remetalled.
Since automotive engines, for many years, used cast in white metal bearings (Gardners did even after WW2, and did not change to thin wall bearings until the late 50s or 60s ) So you might be able to find someone who could remetal the bearings for you (May be costly )
Then you are in Catch 22. You need a lathe to bore the white metal to size, but your ML7 is U/S until the new bearings have been finish bored and then scraped to fit!
I suppose that as a "nothing to lose" desperation mode, having taken all the dimensions, you could use the lathe to turn up Phosphor Bronze bushes to replace the white metalled shells, followed by some careful bluing and scraping
|noel shelley||20/12/2020 19:39:28|
|390 forum posts|
Gentlemen, Firstly to all who have commented - thank you ! The alloy is Glacier T1. As to the customer finishing/ scrapeing the bearings this would be an option and cheaper ! Fully finished bearings would be the norm, possibly a few thou undersize to allow for wear on the mandrel and be allowed for with extra shims, or finished to the customers mandrel dimensions.Having the mandrel surface ground to an undersize is also a thought. It is to you that I have come to seek advice before I even start to experiment with this project. If as some think, it has some merit then I will see how I get on, and let you know.
Make the best of Christmas and keep safe. Noel.
4235 forum posts
Something useful like that tends to have a life of its own, like the meek clutch, suddenly all sorts of different lathe owners want on board
5207 forum posts
The original bearings are solid white metal -- no bronze or steel backing -- and are close to 1/4" thick in the wear areas. So scope for rescraping far exceeds the lifetime of the rest of the machine.
The time-honoured method is that when there are no more shims left to remove, you file or machine down the flat surfaces where the shims sit to allow a new range of shim adjustment. It's hard to imagine so much wear that the whole of the thickness of the white metal is exceeded. You would have to machine those flat surfaces down by close to 1/4" before the bearing was no longer useable. That's a hell of a lot of wear. More than I have ever seen on an old lathe headstock.
I'm sure the reason they are no longer manufactured is lack of demand making short production runs unprofitable. Plus not many people these days have the skills or patience to scrape the new white metal in. Myford's new bronze bearings and hardened spindle are a fit and forget job, apparently.
If you do go ahead and make some, you would probably need to make a die to cast them in. Using a headstock as you propose mightl not allow for shrinkage of the metal during cooling. I can't remember if the originals were machined on the outside diameters or precision die-cast. Perhaps the latter but not sure now.
And I would not expect demand to be that great. Very few posters on here over the years have had to replace the whole bearings. Shimming does the job in the vast majority of cases and a modicum of scraping takes care of almost all of the rest. Then there are useable secondhand sets available on eBay from the regular Myford breaker dealer types that would seem to fill any leftover demand.
Most who spring the coin for the Myford new spindle and phosphor bronze bearings probably do so because they lack the skills or patience to do the scraping and also have a spindle that has been scored beyond use.
One thing I have wondered about is the possibility of turning up then splitting a new set of bearings out of a soft leaded bronze that is compatible with the unhardened old spindle. Plenty of pre-war lathes used this combination, eg the Drummond/Myford M-type. If you particularly wanted white metal, you could turn the bronze bushes with oversize bore and cast in a few millimetres of white metal to do the bearing work.
Another thing to look at is the possibility of setting the headstock up in the mill and machining the existing bearing retainers to fit modern taper-roller bearings -- something Myford should have done about 1960.
|Howard Lewis||21/12/2020 16:52:58|
|4455 forum posts|
Posibly the hard way, but is ther any mileage in measuring the shaft diameter, and finding a set of steel backed shell bearings from, say a car or motorcycle engine?
Having found your bearings, you then machine up a bush to fit the parent bore in the Headstock (Shim for a perfectly round bore when measuring ) You then need to make a bush, to tolerance of "Headstock Bore +0.001 / 0.000" which can be split and clamped in a collet bore which is machined to the OD of the shell bearings + 0.000 / -0.001"round or -0.001" ) .
The shell bearings are then placed in the split bush (which will need slots filing for the retaining tangs of the shells ), and the half bush / shell assemblies placed in the headstock, oiled, and the caps tightened down.
This will not be suitable if the journals are badly scored or have worn to a taper. Correcting that by turning down undersize puts you back in Catch 22 again, plus the need to find shell bearings of a suitable size.
Which brings us back to using the lathe "as is" to machine bushes, from phosphor bronze perhaps, to fit the Headstock parent bores, before being split, clamped in a collet and fine bored to fit the shaft with minimum clearance.
Helical oil grooves could be carefully "screwcut" before being removed for fitting, before finish boring, possibly.
The grooves do not need to be particularly deep, 0.020" should be quite adequate, to spread the oil.
If this works you are in business again. Non standard, but as already said, How frequently do you expect to have to replace the bearings? If it is a ML7 it could have taken over 70 years to wear out the originals
|noel shelley||23/12/2020 13:16:45|
|390 forum posts|
Firstly thanks to all who have offered advice or comment !
The story so far ! The bearings are a solid cast type, NO steel backing or bronze insert. The white metal originally used was a cheap BS type Sn,Sb,Pb,Cu alloy that is still made. The suppliers normal min order is 20Kg but stock is only 7.5Kg so they have sold this to me at the 20Kg rate - A very good start ! The bearings are a push fit in the headstock since white metal will not tin to cast iron. Before I go to Ebay, does any one have a redundant ML7 headstock casting and a worn out set of bearings I can buy ? If the mandrel was also available this would give me dimensions and a better idea as to final fit Etc ?
One member asked where I'm based, near Hunstanton, North Norfolk.
To All of you, make the best of Christmas, and God bless. Noel
|1527 forum posts|
I noticed currently there is a headstock casting on eBay.
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