By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by Allendale July 23rd

Myford bearing taper

All Topics | Latest Posts

Search for:  in Thread Title in  

Articles

Lathe Bearings

Lathe Bearings

In The Model Engineer, issue 2427 of November 27 1947, E.H. Doughty, then Chief Technical Engineer of British Timken Ltd. wrote a lengthy technical letter to refute and address some of the adverse comment that had been made about roller bearings.

Neil Wyatt17/08/2014 20:19:47
avatar
Moderator
16257 forum posts
679 photos
74 articles

I'm planning to make an accurate spindle running in plain bearings. I want to use a small version of the Myford -style tapered front bearing. This seems to be the best and simplest way to make a plain bearing adjustable for wear/play without using a split bearing. Can anyone tell me what the Myford taper angle is?

Neil

Brian Wood18/08/2014 09:53:37
1931 forum posts
37 photos

Hello Neil,

2 degrees and 25 minutes inclusive. Source Tubal Cain Model Engineer's Handbook 3rd Edition

Brian

Emgee18/08/2014 10:13:18
1147 forum posts
206 photos

Hi Brian

Viewing the picture of a spindle at CotswoldsPhil album

http://www.model-engineer.co.uk/albums/member_photo.asp?a=33350&p=542106

makes me think itis greater than 2deg25min taper.

Emgee

Edited By Emgee on 18/08/2014 10:13:51

Edited By Emgee on 18/08/2014 10:15:59

Brian Wood18/08/2014 10:27:49
1931 forum posts
37 photos

Hello Emgee,

I was only quoting what the great man had published, but I agree with you; checking Morse taper standards shows the half angle for say 2MT is not far away from half that value..

Maybe the figure should have been for the half angle, running a taper as fine as MT would grab and lock up in moments.

That would make the bearing taper Neil needs to be 4 degrees and 50 minutes, more in the category of self releasing too. Well spotted!

Regards Brian

CotswoldsPhil18/08/2014 10:29:29
avatar
196 forum posts
112 photos

Hi,

That's my picture uploaded just last week - glad to be of service. If the spindle was still on the bench I could check it for you. Just with a protractor over the picture says it's more like 20' inc.

Regards

Phil H

Brian Wood18/08/2014 10:41:32
1931 forum posts
37 photos

Hello Phil,

Tubal Cain's book could have a typo then, that would make the angle 20 degrees 25 minutes---it makes a lot more sense at that. I have in the past taken my spindle out and from memory it is as you say, a much steeper taper.

Sorry Neil, it's all looking like a bugger's muddle now, maybe someone else can weigh in with a correct answer.

Regards Brian

Neil Wyatt18/08/2014 10:51:15
avatar
Moderator
16257 forum posts
679 photos
74 articles

I forgot it was on the mandrel nose drawing!

The great man was pretty good at getting confused about half-angles.

I spent a good while trying to check out the formula on page 3.1, (3rd edition), where x should be radius not diameter and the formula will then give the correct single-sided taper, not taper on diameter.

He doesn't seem to have registered that 2 * tan (theta/2) is not the same as TAN (theta), although the error at small angles is... small.

I was thinking about an included angle of about 5 degrees or 1 in 10. That would make it easy to adjust running clearance - a 20tpi thread for the thrust bearing adjustment would give 5 thou adjustment per turn. Assuming a precision run fit of 0.001", that would be 10 thou away from locking up.

Problem is that bigger angles are more critical for the adjustment.

More thought needed!

This is for a new headstock for a Super Adept by the way, aim is to make it a BGSC lathe. The existing spindle has 2 thou of wear and the front bearing has been cracked during an attempt to adjust it out. The bearing centreline drops by about 1/8" at the tailstock over the full length of the bed.

Other alternatives are small roller bearings or magneto bearings, but these all seem to have excessive OD's of about 1 1/4" to pass a 1/2" spindle, which is needed to accommodate an 0MT taper.

Neil

Michael Gilligan18/08/2014 11:04:11
avatar
13559 forum posts
586 photos
Posted by Neil Wyatt on 18/08/2014 10:51:15:

This is for a new headstock for a Super Adept by the way, aim is to make it a BGSC lathe.

.

Now there IS a surprise !!

MichaelG.

John Stevenson18/08/2014 11:40:15
avatar
Moderator
5068 forum posts
3 photos

Well if I had know it was for a sooper non-adaptable lathe I wouldn't have bothered reading this post............yawn.

Neil Wyatt18/08/2014 13:09:51
avatar
Moderator
16257 forum posts
679 photos
74 articles

I knew there'd be trouble if he found out!

It's alovely set of castings from which to make a small lathe!

Neil

Michael Gilligan18/08/2014 13:43:40
avatar
13559 forum posts
586 photos
Posted by Neil Wyatt on 18/08/2014 13:09:51:

I knew there'd be trouble if he found out!

It's alovely set of castings from which to make a small lathe!

Neil

.

I look forward to seeing what can be done.

Although the single taper is perfectly viable, you might like to consider the "double cone" arrangement that was commonly used on Geneva Pattern, and early Webster Whitcomb lathes. [see here for a couple of good cross-sectional drawings]

These are usually hardened steel on hardened steel, but I'm sure that other material combinations would work too.

The idea is that the steep taper takes most of the thrust, and allows the other taper to be very shallow without risk of it sticking.

MichaelG.

Edited By Michael Gilligan on 18/08/2014 13:52:20

Neil Wyatt18/08/2014 14:10:14
avatar
Moderator
16257 forum posts
679 photos
74 articles

I know the double taper arrangement. My congratulations to anyone who can turn a mating double-taper bush and spindle to the required accuracy. I won't be joining them!

Neil

Robbo18/08/2014 22:17:55
1504 forum posts
142 photos

Neil,

I can't do spot-on measurements today, as have got the tremors - the joys of old age!

But a measure with a vernier on an old S7 spindle shows approx. a 10.3mm difference in diameters end to end of the taper, over an axial distance of 57mm.

You can probably work out the probable taper from that - sines, cosines, tangents etc are just something listed in the back of my book of logarithms to me.

Phil have corrected all the typos - and there were many.

Neil Wyatt19/08/2014 11:25:33
avatar
Moderator
16257 forum posts
679 photos
74 articles

Thanks Phil,

That works out at about 1 in 6, or 1 in 12 on each side. I was looking at 1:10 but this made the front of the bearing a little thin for comfort, so 1:12 it will be.

Neil

Michael Gilligan19/08/2014 15:09:05
avatar
13559 forum posts
586 photos

One inch in the foot is a very Imperial sort of Taper

Yes ... It seems very likely that Myford would have used it.

MichaelG.

.

P.S. Neil ... are you retaining a 3/8" spindle diameter?

or is the rear bearing worn also?

Chris Trice19/08/2014 16:16:15
avatar
1362 forum posts
9 photos
I've got a spare Super 7 spindle here and just carefully eyeballing it, the taper I get is 12.5 degrees inclusive or 6.25 from the axis. If you're making your own spindle and bearing, I don't suppose it's critical.
Chris Trice19/08/2014 16:17:30
avatar
1362 forum posts
9 photos
That figure was got by transferring straight lines onto a piece of paper and then measuring it with a protractor.
Chris Trice19/08/2014 16:20:04
avatar
1362 forum posts
9 photos
Tubal must've missed a "1" off the start of his figure.
Neil Wyatt19/08/2014 17:23:46
avatar
Moderator
16257 forum posts
679 photos
74 articles

Darn it!

I seem to have lost a long explanation of how I intent to go about constructing the headstock.

I'll do some drawings, maybe try a 3D model...

Neil

Chris Trice19/08/2014 23:32:28
avatar
1362 forum posts
9 photos
Based on your first post Neil, you appreciate that any thrust towards the headstock is actually taken by the angular contact ball races? I hope I'm not insulting anyone's intelligence but the comment about Morse taper angles doesn't make any difference because the taper plays no part in resisting movement along the bed. It's purely there so the running clearance can be controlled.

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
TRANSWAVE Converters
Ausee.com.au
Eccentric July 5 2018
Advertise With Us
Eccentric Engineering
ChesterUK
Meridienne Sept 2019
Warco
Allendale Electronics
emcomachinetools
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