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Scraping and Shimming Myford Headstock Bearings

MEW 292 article

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Graham Stoppani17/04/2020 10:52:59
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124 forum posts
26 photos

Having read the above article I thought I'd check my bearings as described. The initial measurements taken at the nose showed pulling the chuck upwards gave a deflection of at least 3 thou while pulling down was less than a thou and backwards and forwards less than a thou as well.

Removing the bearing caps and the shaft for inspection showed the shaft to have very little wear. Likewise, although the bearing shells showed some wear marks they weren't in bad condition considering the age of the machine.

However, applying blue showed that the top of the front bearing was barely in contact with the shaft at all - that would explain the play only in the upwards direction. The blue had been applied with the shims removed and the bearings tightened until the shaft would not rotate and then slackened off until rotation was possible.

Here are a couple of pictures:

bearing caps.jpg

Here you can see the lack of contact.

bearing cap surfaces.jpg

This picture shows blue showing that the white metal bearings are touching, just, and not the bearing caps themselves when assembled without shims. It is also visible on the right side of the shell on the bottom of the picture that a recess has been milled along the edge of the shell. There is a corresponding milled edge on the other half of the bearing. (not by me)

Before I try to fix this, I'd thought I'd ask for your opinions of what to do and of any other things to test for. Thanks in advance.

Hopper17/04/2020 11:55:30
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6397 forum posts
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It depends. If you have a small scraper and the skills, you could scrape the high spots down a little until you get a better reading across the full length of the bearing.

Don't tighten the bearing cap bolts down too much when doing this, it can squeeze all the blue out and create metal to metal contact that leaves no blue marks. And you only need to rotate the shaft about a quarter turn or so.

But the bearings do not look too badly chewed up so you may be able to simply remove about three thou from the shims and see how it goes as is. I might be tempted to try this first, seeing the smooth condition of the bearings -- at least from the photos anyhow.

Pete B

Graham Stoppani17/04/2020 12:51:01
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124 forum posts
26 photos
Posted by Hopper on 17/04/2020 11:55:30:

It depends. If you have a small scraper and the skills, you could scrape the high spots down a little until you get a better reading across the full length of the bearing.

Don't tighten the bearing cap bolts down too much when doing this, it can squeeze all the blue out and create metal to metal contact that leaves no blue marks. And you only need to rotate the shaft about a quarter turn or so.

But the bearings do not look too badly chewed up so you may be able to simply remove about three thou from the shims and see how it goes as is. I might be tempted to try this first, seeing the smooth condition of the bearings -- at least from the photos anyhow.

Pete B

Thanks for the words of advice. I was very reluctant to start cutting away at metal, given that this is the first time I've played with white metal bearings. I do have a small scraper that I inherited but have never wielded it in anger before. I'll go and have another try this afternoon and let you know how I get on.

Steviegtr17/04/2020 15:21:50
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2435 forum posts
336 photos

There is a guy on youtube who does this job in detail. Worth watching. Jan sverre Haugjord. **LINK**

You will have to search as he has done a lot of Myford rebuilds.

Steve.

Pete Rimmer17/04/2020 17:35:03
1233 forum posts
65 photos

Jan Sverre's videos are always worth watching. He isn't in it for 'likes' 'subs' or money, he just enjoys sharing his knowledge and helping people.

Graham Stoppani18/04/2020 05:57:05
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124 forum posts
26 photos

Just taken a look at Jan Sverre's videos. Hadn't come across him before. Thanks for the 'heads up'.

Graham Stoppani18/04/2020 18:11:52
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124 forum posts
26 photos

Having reassembled the lathe I now have less than a thou movement on the nose in all directions. However, I ended up not adjusting anything! All I can think is that the front bearing housing just needed tightening up a little rather than re-shimming or scraping. Still I'm not complaining as:

a) The shaft is now in spec for bearing play;

b) I got to learn more about my machine long the way.

Thanks Pete B for another interesting and useful article

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