Myford bearing spacer

Evening all, its me again!

I've been fighting with my super 7 spindle bearings recently. I had them set about right for slow speeds (say under 1000rpm) with no runout or lateral play but the front bearing was binding with either tailstock pressure or when run at higher speed.

No matter what I did with the adjustment I just couldn't get it right so tonight I stipped the spindle out to find what I assume is not the standard spacer washer! It's a length of solid copper wire (as found in twin and earth cable) formed into a 'U' and put between the bearings! Both rear bearings are rough and there was a lot of metal filings in the gap between them so I'm going to replace both of them.

Looking at the myford site they seem to specifiy bearings singularly; I thought you could only buy angular contact bearings in matched pairs?

PS - the only spacing washer I can find online is £9! I'm almost tempted to stick the spindle back in to make one....£9 for a washer with a bit cut out?!!

You don't need "matched pairs" of these bearings, but you do need to fit them back to back. Remember which way round yours were when you removed them? Or, given the copper wire washer, maybe they were fitted wrongly, which would add to your problem .

Hi robbo, thanks for the reply. My bearings were fitted with the more open faces of the bearing facing in towards eachother.

Can't see anywhere on any drawings that's actually shows you which way around to fit them.

The more open faces should face outwards - pictures from the Myford manual in this thread **LINK**

Nigel B

Hello Nick,

​I confirm what Nigel B says above, the bearings are fitted back to back with the open faces pointing outwards.

​The outer races are separated by a washer with an oiling gap through it, positioned vertically and the bearing rings close the two races together as a 'solid' bearing. The Myford Super 7 handbook shows the headstock spindle support in great detail and more importantly, the correct way to set up preload and so on. It would pay you to buy or view the relevant pagers; others will be able tp post links for you. My browser will not allow me to do so.

Regards
Brian

Edited By Brian Wood on 12/01/2017 09:08:07

If you look in the manual on page 25 and 26 Figs 34 through 36 you can see that the bearings are fitted with the 'free face outwards. The spacer is Myford Part No A1991 Bearing Spacer Washer which I cannot find on Myfords online parts but eMail them and I am sure they can oblige. If you don't have a manual you can down load at

**LINK**

The system works like this.

The spacer washer allows the outer journals to be clamped together by the locking rings. The inners are preloaded by the split collar outboard of the sleeve gear on the end of the spindle acting through the sleeve gear and nipping the inner journals between it and the step on the spindle through the distance sleeve.

regards Martin

The spacing washer thickness is only nominal, around 0.015"-0.020" as I recall when last I saw it. Make your own from steel but not copper wire!

Thanks for the replies as always.

So, it looks like my spindle problems were genuine - bearings the wrong way around and a Micky Mouse spacer! At least I wasn’t going mad without reason.

Just come off the phone to Myford – they have the bearings and the spacer in stock and it should all be with me tomorrow.

Also, asked about the front tapered bearing as they haven’t been available new for a while and they said there is a batch being manufactured shortly for the small bore super 7’s, they have stacks of the big bore bearings in stock apparently.

My front bearing looks to be showing wear but in good condition, same with the spindle so that’s some good news at least.

Cheers gents, I’m sure I’ll have new questions when fitting the bearings this weekend!

Nick,

When fitting the spacer between the two bearings make sure the gap is at the top in line with the oiler hole. The gap is to allow oil to get to both bearings.

Eric

Hi Eric

Yes thanks for the tip - I think this might be why the bearings are in such bad condition, the gap in the home made wire spacer was very big, about 90°, so I think most of the oil was missing the bearings, rather than meeting the top of the shaft and being pushed into the ball races I think it was simply running around the shaft and draining right out the bottom.

Cheers

Edited By Nick Taylor 2 on 12/01/2017 14:43:06

Kwil

That's correct - the spacer is a nominal 20 thou / 0.5 mm

Parts have just arrived so I'll get cracking later on if I get chance. Brand new spacer was £3 something... compared to used ones on certain websites for £10+!

The wire 'spacer' that was fitted to mine was 1.54mm and only copper so very soft. Would explain why I couldn't get the bearings set right.. oh and they were the wrong way around.

I'm amazed it ran as well as it did to be honest, if you weren't using the tailstock or the high speeds you probably wouldn't notice it, just hope no damage has been done to spindle or the front bearing.

Cheers

With copper wire as a spacer it's probably just as well that the bearings were the wrong way round. The thrust load would be taken on the rear bearing rather than the front so it would have worked OK as a thrust bearing but the radial constraint would be potentially compromised. Essentially it would work as a single rather than a pair. Hate to think what would happen to the front bearing clearance if you were cutting away from the headstock or machining the a rear shoulder on an item.

regards Martin

Evening all,

Well the new bearings are in and the machine runs so much smoother and I can put a lot of tail stock pressure on and there is no sign of any movement in the spindle and I've run at 2k rpm for 10minutes with only the slightest warming of the front bearing.

However - there is now a noise that sounds like a tin bucket full of marbles being slung around! Fairly sure it's coming from the new rear bearings. I soaked the bearings in oil before I fitted them and have kept them well oiled during the test runs. I know they don't need to be swimming in oil, they make a very distinctive droning sound when they are over full, but this isn't it.

Seems that I've solved one problem but created another!

sounds like a tin bucket full of marbles being slung around!

My Super 7 spindle is pretty quiet in direct drive & a bit "growly" in back gear - but only when the feed gearing is disengaged. The gear train is rather rattly when engaged, so I run with it out of engagement unless required.

Have you got the thrust bearings adjusted too tightly (the nut at the LH end of the spindle) ?

Nigel B

Hi Nigel,

Do you mean the split collar on the end of the spindle? Or the left of the two locking rings?

The collar is just nipped up and lines up pretty much perfectly with the scribed line on the spindle. The sound is almost a rattle, I would assume this would tell me that there is not enough load on the bearings rather than a droning or humming to tell me there is too much...

Cheers

What you describe as a "split collar" is the preload locknut at the end of the spindle. Given that you have changed the bearings and spacer, I doubt that any scribed lines are valid now. Did you look at the link I gave above to the Super 7 Manual - page 26 describes the procedure for adjusting the rear bearings.

Nigel B

Too much oil in the rear bearings.

Eric

Too much oil in the rear bearings.

How do you put too much oil in an open bearing ?

Nigel B

Hi Nigel, thanks for the replies.

Think I've cracked it. Don't think I had anywhere near enough preload on the bearings. I've slackened everything off and started again... Twice.

Has been running for about 10mins now with no errant noises, it's like a sewing machine! New bearings and a resilient mount 3 phase motor have totally transformed the lathe.

Earlier on I was trying to find out if the noise was in the spindle or the counter shaft, so I chucked up a short length of 1inch bar and turned it down to 12mm to fit in my cordless drill with the idea of spinning the spindle with the drill and using the 'screwdriver to the ear' method for finding the noise. Unfortunately the cordless drill (a fairly new makita) was louder than the lathe was at 2k rpm and I couldn't hear anything!