Myford Super 7 Headstock Bearing Removal

[Tom GullanParticipant @tomgullan59234]

Hello,

I have a Myford Super 7 lathe. Can anyone tell me how to go about removing the wick which supplies the oil to the headstock front bearing? I need to replace this bearing. I assume that it is pressed put.

Regards

Tom

[Tom GullanParticipant @tomgullan59234]

[Cyril BonnettParticipant @cyrilbonnett24790]

Try

http://www.model-engineer.co.uk/forums/postings.asp?th=91358

Cyril

Edited By Cyril Bonnett on 21/12/2015 21:21:42

[KWILParticipant @kwil]

On the tailstock face of the headstock below the main spindle there is a socket grubscrew. Remove this screw and insert a long pin/needle, this will push through the wick stem and stop it pushing out when you withdraw the headstock spindle.

Now with the spindle removed you can recover the wick by hand. Examine/replace with new. Spring is around the round base of the wick which is square section at top (in contact with the spindle inside the tapered front bush).

Having pushed the wick down, replace pin to withstrain the wick during reinsertion of the spindle (gets trapped otherwise)

Rarely necessary to remove plug at base of headstock.

Make sure you use the correct garde of oil (Nuto 32 or other ISO Grade 32 hydraulic oil) nothing thicker.

Edited By KWIL on 22/12/2015 10:53:33

[LambtonParticipant @lambton]

Tom,

Kwil has given the necessary instructions. I strongly advise you to obtain a proper Super 7 handbook which tells you all about the maintenance and use of the machine. Well worth the investment.

[John HaineParticipant @johnhaine32865]

One thing puzzles me – what happens to all the oil that I put in the headstock oiler?

[KWILParticipant @kwil]

It all flows out of the bearings, mostly inside the headstock and runs down to whatever the lathe is mounted on, ie total loss lubrication.

Front bearing is tapered so most flows back inside, some behind the chuck, main rear bearings, some retained with the outer raceway but is also lost inside and out, slightly more out of mine because I have taper roller bearings as mains.

[John HaineParticipant @johnhaine32865]

Well, I guessed that, but it doesn't end up in the drip tray or the shelves of the stand, so must be in a pool in the headstock casting somewhere.

[KWILParticipant @kwil]

Yes if its bolted straight down, if on raiser blocks it can creep out. You should be able to see how big the puddle is, mind you overall the amount of oil used is still small

[speelwerkParticipant @speelwerk]

The original raiser blocks has recesses for a O-rings to seal the driptray, if you do not install them the oil will finally end up on the floor. Niko.

[egaParticipant @ega]

Tom Gullan:

You say you want to remove the front bearing. Can you tell us why?

When I had my well-used S7 headstock professionally over-hauled I believe the front bearing was scraped in in situ. Has your front bearing been damaged in some way?

[Tom GullanParticipant @tomgullan59234]

Cyril, Kwill, Lambaton,

Thank you very much for that information. I have now managed to get a photocopy of the original Super 7 manual.

Ega,

After testing the spindle with a dti I recorded an 0.008" run out. This was recorded with the spindle at its maximum travel i.e. adjusted all the way to the left. After speasking to Myford I was told that there was probably wear in the front bearing and that it would require replacing. I rigged up a puller and removed the bearing last night. I have also ordered a new bearing which should hopefully arrive today (Wednesday). The bearing has one groove which runs in line with the hole for the wick, presumably for the oil. The chap from Myford told me that the bearing should have three grooves if if it was an older style lathe and two grooves if it was a later model. As I said my bearing has one groove so I'm not sure why this is the case. I was also told that I would have to cut the groove/grooves myself.

Regards

Tom

[egaParticipant @ega]

Tom Gullan:

Thank you for taking the trouble to explain. The wick, of course, contacts the spindle and I suppose there has to be radial hole in the bearing to allow this. I don't remember the grooves or their orientation and they don't seem to be shown in my copy of the manual but presumably they are axial ie parallel to the spindle.

Incidentally, one drawing in my manual seems to show the Mk 1 overhead oil reservoir.

Good luck with your replacement!

[KWILParticipant @kwil]

Tom,

If you do really get up against it there are a couple of travelling OLD Myford engineers who do maintenance and repairs. Someone on here will no doubt provide the contact details if required.

[LambtonParticipant @lambton]

Tom,

I am pleased that you have obtained a manual.

Last year I put new rear bearings in my Super 7, quite unnecessarily as it turned out, but in the going I carefully examined the front bearing and the spindle. The original scraping marks showed all around the front bearing bush and the spindle surface was like a mirror. The bush has a single oil groove that obviously is in the 6 o’clock position along the axis of the bush stopping just short of each end. There is no point in having more than one groove as it is only in the 6 o’clock position that it can function as an oil distribution “gallery”. Additional grooves would probably act as oil scrapers and so interfere with the oil film between the bush and the spindle. A single groove in this type of application is standard engineering practice.

The reason I elected to replace the two rear angular contact ball bearings was that after I bought a better oil gun and pumped oil into them they became noisy at speeds over about 800 rpm. This was a strange and not nice sound. After putting in the new SKF bearings and adjusting the headstock as per the Myford service instructions I got exactly the same noise after pumping oil into the new bearings. Careful examination of the old bearings showed they had no faults. After a little research on the net I found out that over lubrication of such bearings will make them noisy presumably due to the excess oil being churned up by the balls and their cages. I have now removed the oil nipple from the rear bearing and replaced it with a flip top oiler which I apply oil to dropwise, a few at a time from a normal oil can before starting work and occasionally during the work if necessary. By this method I can control the amount of oil going into the bearings which is not possible using the oil gun. All is now quiet.

On the subject of over oiling this should not be possible for the front bush if the spindle position is adjusted correctly i.e. with the minimum radial clearance as per Myford instructions. If you look at the illustration on page 19 (fig 27 ) of your manual you will see that the lubricator (7) is quite a bit below the bottom of the spindle so no oil can run into the bearing by gravity (a big problem with the previous ML7). Oil can only get to the spindle via the capillary action of the wick. So although the lubrication is a “total loss type” the loss will be absolutely minimal providing the bearing is adjusted properly.

The O rings incorporated in the raising blocks are to prevent coolant rather than lubricating oil running out of the drip tray into the cabinet.

It may be that some owners pump oil into the front bearing but this is not how the lubrication system was designed and is certainly not necessary – just keep the lubricator (item 7) topped up with grade 32 hydraulic oil (Esso Nuto H32 or similar).

[AjohnwParticipant @ajohnw51620]

Personally if I was replacing the bearing I would fit a new spindle as well. There will be some wear in that. They should have spares stock. I asked and they had none but made some shortly after.

I intended to rescrape the bearing true but bought a boxford instead.

John

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[Tom GullanParticipant @tomgullan59234]

 

Gentlemen,

Thank you very much for all your help.

I used a piece of 3 1/2" aluminium pipe and made a puller to remove the defective bearing. When it came to installing the new bearing I had a friend make me two cups, each to the diameter of the bearing's ends – my lathe was out of action. These cups helped to ensure that the bearing entered straight.

I check for runout on the spindle. I'm now registering a mere quiver on e needle instead of 0.008".  Happy days…!!

 

Edited By Tom Gullan on 24/12/2015 00:16:12

[AjohnwParticipant @ajohnw51620]

It's best to make the parts needed first before dismantling the lathe. I did but with ball races etc it's important to try and make sure that the all thread is central to the bearing when it's pulled in. Maybe a bit of a boss that locates in the shells on the discs used to "pull" them in. This probably doesn't matter on S7 bearings as they are so long but other types can be pulled in slightly slanted.

I managed to do it without that but it would be easier with the bosses. The same applies to getting the spindle out if the bearings are tight fit as they usually are. I had problems until I carefully squared things up by eye – it then needed less force. Maybe a sleeve that fits in the the spindle and locates the all thread centrally would be a good idea.

John

–

[Cyril BonnettParticipant @cyrilbonnett24790]

links to Super 7 and ML7 manuals

**LINK**

**LINK**

[Neil LickfoldParticipant @neillickfold44316]

I had a test piece checked on a Talyrond machine a couple of months ago. The result was better than 0.003mm , so I was very happy with the results. I was going to replace the main spindle bearing, but decided to scrap and blue it to the spindle some 25 years ago or so. I am still very happy with the machine.

Neil

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