Myford bearing taper

[Brian WoodParticipant @brianwood45127]

Neil and Nigel,

A few years ago, Ken Willson wrote up a short article in MEW which describes fitting a pair of taper roller bearings at the rear of the Myford spindle in place of the angular contact bearing specified by Myford. I found those were prone to brinelling of the races and thus becoming noisy if there was a hint of exceeding the pre-load..

I have found the modification completely satisfactory and without any drift in pre-load after fitting. Vehicle front axles use them exclusively; they are subject to all manner of shock loads and still run well for years.

A friend has changed his having stripped the spindle for other reasons and he too is delighted with the result.

Regards

Brian

[Neil WyattModerator @neilwyatt]

LBSC had the opposite experience with his Milnes and sent the roller bearings back!

He may well have not known how to adjust these new beasties.

I have a great illustrated letter from Timken to ME I will scan and put up.

Neil

[Neil WyattModerator @neilwyatt]

I've posted the Timken letter here.

I wish I could get scans of the tailstock articles of that quality!

Neil

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Neil Wyatt on 20/08/2014 20:51:23:

I've posted the Timken letter here.

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Thanks Neil

Very useful information.

MichaelG.

[Brian WoodParticipant @brianwood45127]

Neil,

Here here

Brian

[Michael GilliganParticipant @michaelgilligan61133]

This, about the Hardinge Cataract pre-loaded Ball-Bearing arrangement, makes interesting reading as an alternative to Timken Taper.

… Two of the ways to elegantly skin this particular cat.

MichaelG.

[Chris TriceParticipant @christrice43267]

This subject couldn't be more timely. I've literally just ordered two taper roller bearings to do this conversion on my Super 7. From memory, wasn't there a question about getting the correct size bearings? Simply Bearings do taper roller bearings that are direct replacements (52mm O.D, 25mm I.D, 15mm width). SKF do similar but the width is 16.2mm which might need some parts to be shaved.

[Chris TriceParticipant @christrice43267]

… and Ken's article is in issue number 175 for interest.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Neil Wyatt on 20/08/2014 13:06:00:

… I find it hard to understand why Myford never used or moved to taper rollers, which were well understood by 1947 …

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Neil,

I think you found the answer to that one, when you looked at the Adept:

A Taper Roller Bearing [or preferably a back-to back pair] in the Nose of a Headstock is fairly bulky 'diameter-wise' … Installing TRB in the existing casting would probably have compromised the Myford design, either in headstock strength or spindle diameter.

Without heavy modification to the casting … I think the plain taper bearing at the front with taper roller[s] at the rear is the optimum arrangement in the space available.

MichaelG.

[ I hope the conversion goes well, Chris ]

[Neil WyattModerator @neilwyatt]

I can understand that customer conservatism would gave been a good reason in 1947, as evidenced by why caused Timken's response.

They had further opportunities with the two major redesigns of the lathe

They could have beefed up the new S7 castings a little, though this was not that l;ong after the ML7 appeared and added a lot of different features.

I don't understand why a lathe with the much bigger spindle of the Connoisseur which meant major redesign and was quite recent didn't get them. That huge hand-scraped bearing must have been a major chunk of the cost of making the new machine.

Neil

Edited By Neil Wyatt on 22/08/2014 09:30:45

[Michael GilliganParticipant @michaelgilligan61133]

… I wonder what happened to the Myford Tempest [pictured here]

MichaelG.

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Edit: apparently a.k.a. Mini-Kop, and it looks like there may have been a standard headstock casting under that nice chunky square cover.

Edited By Michael Gilligan on 22/08/2014 09:57:00

[Brian WoodParticipant @brianwood45127]

Chris,

You may already know, but the conversion needs clearance to be machined into the bearing adjusting rings. Ken's article has the drawings. In some cases you may need the shortened spacer too.

With having only one lathe, I got spare rings from Myford and pre mached them before I stripped the lathe.

I think you will be well pleased with the result.

Regards

Brian

[Ian S CParticipant @iansc]

Lawrence H. Sparey, in "The Amateur's Lathe" in 1950 mentions ball, and roller-bearings, saying that the general consensus of opinion seems tobe such head-stocks are productive of "chatter" on the work.Fundamentally, there seems no reason why this type of bearing should not be excellent in every way.

Ian S C

[Chris TriceParticipant @christrice43267]

Thanks Brian and Michael. I just read the article on the conversion. In addition to buying the bearings quoted, I’ve also located and bought two TRB’s that have the exact same size as the old Myford ones so hopefully a minimum of modification. Fortunately, I have two spare adjuster rings to do this too if I have to. I might start a separate thread when the bearings arrive.

[Roderick JenkinsParticipant @roderickjenkins93242]

Posted by Ian S C on 22/08/2014 11:28:05:

Lawrence H. Sparey, in "The Amateur's Lathe" in 1950 mentions ball, and roller-bearings, saying that the general consensus of opinion seems tobe such head-stocks are productive of "chatter" on the work.Fundamentally, there seems no reason why this type of bearing should not be excellent in every way.

Ian S C

I guess that the perception that roller/ball bearing headstocks chatter is to do with tolerances. A solid bearing would be scraped in to provide a good fit. Not really possible with bought in bearings. 70 years on, I would imagine that the manufacturing techniques have improved somewhat for both the bearings and the seats.

I'm very impressed by my Arrand ball bearing milling spindle. These are supposed to be good for 8000rpm. I don't know what the bearing arrangement is? – anyone taken one apart?

Cheers,

Rod

[Ian S CParticipant @iansc]

It was a very different world late 40s, early 50s, Britain and the rest of the world were recovering from WW2, there still was rationing, and Myford probably was a bit down the list, DS&G, Colchester, and others would take all the allocations of bearings.

Ian S C

[Chris TriceParticipant @christrice43267]

I tackled the Myford conversion today. The bearings that were supposed to be 15mm wide were in fact 16.25mm wide (identical to the quoted SKF bearings) so the conversion followed the exact same route as the magazine article. You can definitely feel a more positive point between there being play and no play when adjusting the bearings and as a result you can control the clearance of the spindle at the bronze bush end far more precisely. You can also sense that when pressure is applied via the tailstock revolving centre, things are more solid yet still free wheeling.

[Michael GilliganParticipant @michaelgilligan61133]

Sounds like a great success, Chris.

Although it is very sad to see that a bearing supplier can be so far out when specifying dimensions!

… out of interest, do you have the code for the bearings you received?

MichaelG.

[Brian WoodParticipant @brianwood45127]

Hello Chris,

That mirrors my experience complelely, and the adjustment holds much better over time.

I said you would be pleased with the outcome.

Regards

Brian

[Brian WoodParticipant @brianwood45127]

Neil,

Going back to your original question that started this thread, Ken Willson's article in MEW 175 has a most helpful plan view picture of the lathe spindle, from which it is possible to measure the cone angle well enough.

I found 12 degrees using a protractor, so Tubal Cain's drawing in the handbook should read 12 degrees and 25 minutes.

Regards

Brian

Edited By Brian Wood on 24/08/2014 11:10:36

[Chris TriceParticipant @christrice43267]

Taper Bearings for Myford conversion. SKF http://simplybearings.co.uk/shop/p14781/SKF+30205J2Q+Metric+Single+Row+Taper+Roller+Bearing+25x52x16.25mm/product_info.html

[Chris TriceParticipant @christrice43267]

And these were the ones I also ordered claiming 15mm width but were identical to the SKF item in dimensions. http://simplybearings.co.uk/shop/p43728/30205JR/30205J+KOYO+Narrow+Section+Steering+Head+Set+Taper+Roller+Bearing+25x52x15mm/product_info.html

[Michael GilliganParticipant @michaelgilligan61133]

Thanks, Chris

… useful reference

MichaelG.

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