Myford headstock bearing replacement

[IntrestinParticipant @intrestin]

Has anyone replaced the front bearing on a Myford super 7 headstock?.

I have an annoying squeak from this area which sounds like a lubrication issue although there appears to be plenty of oil in the reservoir. When a load from the tailstock is eased off, the squeak disappears.

I have adjusted the bearing using the locking rings at the opposite end to give what i consider enough clearance but it still makes a noise when under longitudinal force.

How easy is it to replace and are there any pitfalls i should be aware of?.

[IntrestinParticipant @intrestin]

[speelwerkParticipant @speelwerk]

Before thinking of replacing the headstock bearing I would make absolute sure it is necessary, perhaps someone in the past tried to adjust the angular bearings and made a mess of it. They should take the load when you apply longitudinal force with the tailstock, if not further adjustment is needed. No doubt many on this forum can give you better information than I on how to make these adjustments, but do mark the position of the locking rings before you make changes so you can easily go back. Niko.

[Tony Pratt 1Participant @tonypratt1]

Sounds like there is no oil getting to the bearing, is there any sign of oil coming out between the bearing front and the spidle? As has been said the rear bearings take the longitudinal force.

Tony

[KWILParticipant @kwil]

There is also a wick (spring loaded) that takes the oil UP to the bearing. The instructions for adjusting the rings and hence the front bearing clearance is included in the handbook. It is quite straight forward, but you will need the C spanners.

[Brian WoodParticipant @brianwood45127]

You say there is plenty of oil in the reservoir cup; that rather suggests to me it is NOT getting where it is needed and as KWIL suggests it needs investigating. It means stripping out the mandrel to get to the spring loaded wick in the bottom of the front bearing. Mine is quite thirsty and I top up weekly.

There was a short article in MEW about 2 years ago by Ken Willson [ sorry, the reference was something I didn't note at the time] which described replacing the angular contact bearings with taper roller bearings. It was a clever mod. I adopted and fully endorse.

You will need to machine the screwed rings to accept the taper roller bearings to include it. The easiest approach is to buy two new rings from Myford to modify before you strip the lathe, unless of course you have access to other facilities to do the work.

Brian

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[custardcatsParticipant @custardcats]

Myford Super 7 thrust bearing adjustment.

Manual is avaiable at http://www.scribd.com/doc/61266710/myford-super7lathe

pages 24 to 26 give all the details. Suggest that you set up these angular contact bearings exactly – especially the pre-load and test for the squeeks before you do any stripping down.

If someone has had the ball bearings out previously it is possible that one – or both -have been put back the wrong way round. Also the spacer ring between the bearings is very important.

In early lathes Myford used Ransome & Marles precision bearings.

Colin

[RobboParticipant @robbo]

The article by Ken Willson was in MEW no 175, April 2011 (top marks Brian for "2 years&quot.

The occurrence of the noise suggests the spindle rear bearings, which take all the thrust and so don't last forever. Myford recommend "should be oiled daily", also "overloading will cause rapid deterioration", this refers to the preset overload, so if maladjusted in the past may be the cause of the problem.

By all means check that the front bearing is receiving oil, it usually flows freely from round the spindle end.

Phil

[KWILParticipant @kwil]

I would also point out that when the front bearing was factory fitted they were scraped in and checked.The preload of the rear pair of bearings should not be excessive, little more that "tighten by hand"

Where are you located?

Edited By KWIL on 13/03/2013 14:49:00

[NobbyParticipant @nobby]

HI
When setting front bearing asumeing oil is getting to front bearing move the ball bearing and spindle back until the cone contacts the tapered bush until it dont rotate (solid) . correct clearence can be set
rotate the rim back 1/4" 15 degrees . Nobby

[KWILParticipant @kwil]

Not much oil around the tumbler reverse gear pins is there?

[DMRParticipant @dmr]

You could try the screwdriver (or other rod) test to try and determine which end the noise is coming from first. One end on the mandrel and the other end hard against the back of your ear.

It is known that if the mandrel got really hot, as in heavy loading, the felt wick melted and tended to glaze over. Most likely to happen when drilling or using the tailstock for between centres working. It also tended/tends to wear a groove in the mandrel under those conditions! A possible test you could try if all else fails is to release the rear bearings off and stick some oil directly into the front cone. Reset the bearings and try some "noise" production, even applying a bit a bit more oil to the top of the cone outer surface. If no noise initially, then it's that wick

To examine the wick assembly, you have to separate the head from the bed. Removing the mandrel alone allows the wick to protrude into the cone bearing centre, but you should not then attempt to re-assemble/reinsert the mandrel, pushing the wick back in place as you go as this action will most likely just bend/destroy the wick.

[KWILParticipant @kwil]

Not true about the need to remove the headstock to examine the wick, below the spindle on the right hand face of the headstock there is a grub screw, if you remove this you can insert a long pin, (dress making type), this will hold the wick down, remove the spindle and then release the pin, if the wick top end rises into the bearing bore you can see it and assess its condition, then depress the wick by hand and reinsert the pin to hold it down. Insertion of the spindle does not then decapitate the wick!! Do not forget to remove the pin and replace the grub screw with a hex key.

[Chris TriceParticipant @christrice43267]

I tend to fill the oil cup on the side each day AND put a drop or two directly on the spindle where it emerges from the bronze bush. Runs sweet as a nut.

[Martin KyteParticipant @martinkyte99762]

Youshould definitely make sure the issue really isn't the rear bearings.

This is the Gospel according to Malcom (The original Myford works proceedure)

1. Power Down

2. Remove all belt tension.

3. Remove Chuck

4. Rotate RH collar one complete turn. (top towards you).

5. Rotate LH collar one complete turn. (top towards you).

Spindle should be completely free of front bush.

6.Loosen allen screw on collar at end of spindle.

7. Using the Allen key tighten collar as tight at it will go by hand.

Inner tapered roller races are now locked together with correct pre-load.

8. Back off LH collar one complete turn + a bit (top away from you)

9. Rocking the spindle by holding the spindle nose tighten the RH collar by hand (top away from you).

10. When you feel resistance to movement stop.

11. Collar should be just tight enough that spindle can just be moved by hand holding the nose.

12. Do up the LH collar by hand (top towards you).

You should still feel resistance when turning the spindle by the nose.

13. With the crescent wrench on the LH collar tap the end smartly with a 12oz hammer.

The spindle should move forwards by a couple of tenths and be completely free running.

14. With the lathe running slowly (lowest direct speed) put the oil gun in the front oil cup and pump until oil issues from the front bearing. (It comes out of the back and is sprayed around by the bull wheel at least it did on mine)

15. All should be sweetness and light with great rejoicing in heaven and on the earth.

You stand a better chance of scraping the front bearing to recondition than you do trying to replace, I believe it is a shrink fit.

regards Martin

[KWILParticipant @kwil]

Martin, Point 7 above, the standard Myford S7 bearings are not taper roller they are single row angular contact ball bearings. Only a few of us have non standard taper rollers fitted.

[Martin KyteParticipant @martinkyte99762]

mm, I have angular contact bearings too. It matters not a jot the proceedure is the same.

Martin

[Martin KyteParticipant @martinkyte99762]

Oh and if lubrication is in question the trick of using the oil gun in the oil cup to flood the front bearing should help the diagnosis.

regards Martin

[RobboParticipant @robbo]

With regard to Martin's last point in the Gospel according to Malcolm (may he rest in peace), re scraping the front bearing rather than replacing, this was the standard procedure when a Super 7 was being overhauled in the factory, even when a new spindle had been fitted. Fitting a new bearing would be the exceptional case.

At the appropriate stage in the procedure the headstock would go to Brian (the master scraper!) and he would scrape in the front bearing to the spindle. He also scraped the underside of the saddle after regrinding to fit the bed.

Generally, new rear spindle bearings were fitted as a matter of course.

Phil

[andy may 1Participant @andymay1]

Hi!

I found this thread while searching for an answer to my headstock woes. I've an early Super 7 with the oil window, 1958 or so. Fantastic lathe in great condition, except that last winter my headstock totally seized!! So i bought a C spanner (and the correct oil….) and began a seemingly endless quest to get it properly adjusted.

Getting closer i hope – it sounds a bit better at least, and is drinking less oil. Still kinda noisy from the rear bearing area.

My rear collar is almost disappeared into the housing though. Is this normal?

Also more confusingly my collars appear to rotate in the opposite directions to in Martin's instructions from the works. Is that even possible?

thanks in advance

Andy

[RobboParticipant @robbo]

Andy,

Unless something remarkable has happened to your headstock, I doubt the threads are any different from those described by Martin.

What is confusing is the difficulty in describing in text what is a simple operation to perform.

Both the collars are R/H thread, so turning the Right one towards you will slacken it off, turning the Left the same way will tighten it. So points 4 and 5 loosen the Right hand and tighten the Left, so pushing the spindle to the right and freeing it from the front tapered bearing.

The outside shells of the bearings are clamped tightly together by the adjusting collars, whereas the inner shells are held by the collar on the end of the spindle, and it is these that are used to set the preload.

There is a spacer between the 2 outer shells, this has a gap in it and it is located underneath the oil nipple so allowing the bearing to be lubricated from the inside.

Maybe this spacer is missing from your headstock, so allowing the Left collar to screw further in than it should (and making a nonsense of the preload).

Forgot to load a picture of my Mk1 headstock before writing this, and don't want to lose this so will do it in a minute, you will see that the Right collar is a bit further out from the casting than the Left one, but not much.

Back soon!

 

 

Edited By Robbo on 28/05/2016 11:15:00

[RobboParticipant @robbo]

Andy,

Pic of my Mk1 headstock.  See previous post

 

Edited By Robbo on 28/05/2016 11:15:37

[andy may 1Participant @andymay1]

Thanks for the quick and helpful reply Robbo.

More investigation on my part needed i reckon….

cheers

A

[andy may 1Participant @andymay1]

Me again, more questions….

So after months of faffing around with the adjusting collars i finally bit the bullet and took it all to pieces. Replaced the back bearings and things are a lot better. The front bronze bearing looks pretty good (to me) BUT i realised it had begun to migrate forward slightly in its housing – possibly explaining impossible adjustment issues. I tapped it back in – but afraid to hit it too hard as it's only bronze. Now the machine runs more quietly and smoothly than it has in ages but 2 problems remain –

1. Applying a tailstock centre to a workpiece with a positive action slows down the lathe. I believe it is pushing the spindle back in the bronze cone, but if i advance the collars to try and prevent this the spindle is too tight.

2. It's an early 'oil window' lathe so i can clearly see i'm using an awful lot of oil!! Again i'd want to adjust the spindle further into the headstock but there's really very little adjustment until it's too tight.

On these oil-window machines is there anywhere else the oil can go other than through the bronze bush and past the spindle?

Could someone take a photo of their bronze bush (oo-er) and spindle at the front so i can see if the relative positions look anything like mine? I'm wondering if the bronze bush is still too far forward somehow.

cheers
Andy

[SandgrounderParticipant @sandgrounder]

Posted by andy may 1 on 23/11/2016 22:38:28:

Me again, more questions….

Could someone take a photo of their bronze bush (oo-er) and spindle at the front so i can see if the relative positions look anything like mine? I'm wondering if the bronze bush is still too far forward somehow.

cheers
Andy

No photo at the moment but a few dimensions from my Mk1 S7 if they help,

There is 5mm of bronze bush sticking out of the front of the headstock casting, this is +/- 0.1 as I'm measuring to a cast face,

the ϕ43.8 steel shoulder on the spindle is sticking out 2.5mm and when a chuck is screwed on there is 7mm between the back face of the chuck and the headstock casting, this is slightly smaller than 5mm + 2.5mm due to a shallow machined recess on the chuck back face.

Of course I can't guarantee that these are the dimensions when it left Myfords, someone might have changed the bearing before I got it.

John

 

 

Edited By Sandgrounder on 24/11/2016 07:46:38

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