Myford bearing taper

Hello Chris,

You are of course absolutely right, with tapers as fine as Morse it would only take microns of lateral movement for the faces between mandrel and bearing to run the risk of grabbing and seizing up. A steeper taper, as now turns out to be nearer the truth, resists that and gives much better feedback as the clearance is reduced.

I was trying to equate a quoted angle with other examples of taper angle for reference.

Regards Brian

Edited By Brian Wood on 20/08/2014 09:23:29

Hi Chris,

That's exactly my understanding. I find it hard to understand why Myford never used or moved to taper rollers, which were well understood by 1947, but the plain taper and even a plain thrust washer on bronze bush at the tail is ideal for my needs with such a small spindle,

Neil

When Myford designed the S/7 it was in a time after the war had just finished and the UK was involved in the Korean war and priority was for aircraft and armanents ,lots of industries suffered from this having to modify their products due to non availability of things like alloy steels,chromium plating etc and suitable bearings may not have been available,also there is a lot to be said for plain tapered bearings they do help achieve very good surface finishes ,German instrument lathes used both tapered bronze bearings and hardened steel bearings. If Myford had selected a tapered roller bearing then, I expect that everyone would be now moaning that the type of bearing selected was now obsolete ,at least a bronze bush can be machined up to suit,

My old company circa 1985 purchased a lathe for diamond turning fine finishes and that had plain white metal bearings .

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

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

I've posted the Timken letter here.

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

Neil

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Thanks Neil

Very useful information.

MichaelG.

Neil,

Here here

Brian

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.

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.

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

.

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 ]

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

... 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

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

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

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