Myford Super 7 - funny behaviour

[Johnlukes]

Hi
If I didn't know better I would be sure I have bearing problems.. It seems better when the lathe has warmed up, but can still misbehave even then. Can any one identify the cause?
When I disengage the clutch the motor spins quite happily, it can only be the bearings surely! But they are all lubed properly and there doesn't seem to be any play.. I have a video that should Demonstrate the problem..

http://youtu.be/1gDW6417d8g

Thanks in advance for any help...

 

[Swifty]

Sure sounds like a bearing problem, I'm not familiar with these lathes so I'm only guessing, are the bearings themselves loose in their housing?

Paul.

 

[bazmak]

Hi,if memory serves me correctly the front bearing is a tapered adjustable bronze bush.Depends on the model but if you google you should get a wealth of information,parts,schematics etc

 

[BaronJ]

Hi
If I didn't know better I would be sure I have bearing problems.. It seems better when the lathe has warmed up, but can still misbehave even then. Can any one identify the cause?
When I disengage the clutch the motor spins quite happily, it can only be the bearings surely! But they are all lubed properly and there doesn't seem to be any play.. I have a video that should Demonstrate the problem..

http://youtu.be/1gDW6417d8g

Thanks in advance for any help...

That sounds like the thrust bearing. The one just inside the pulley on the countershaft. Its only under load when the spindle is being driven.

 

[goldstar31]

I have a far older Super 7B- the grey one which I overhauled two or three years ago now. So I am guessing-being almost profoundly deaf anyway.

Basically you have as was said, a tapered bronze bearing but TWO axial bearings under load on the spindle. No doubt you will know all about this and the quite awful job to adjust the play. Frankly, I don't think that this is your trouble and I'd leave this severely alone until you have examined again the various needle roller and plain bearings- to see if they are running hot. So can I be rude and ask whether you are using grease or oil in them? When I bought my wreck of a machine- it had been greased and I had to get the stuff out before oiling. Here, and I further risk comment,the Myford oil gun is a load of rubbish and will rarely oil properly. The oil has to come out- and run clear.

So my thoughts on what is causing the noise- if it not the bearings. I would like you to open the Motor Drive belt guards and see if one or both pulleys are rubbing against either the front cover or the back plate. When I changed from single phase to three phase- I got something similar from the new motor hitting the outer door.

What nobody says is that the Myford lathe can have all sorts of 'funny problems' because it is unstable until it is firmly bolted down. My answers MAY help but it isn't quite straightforward as I know.

Regards
Norman


Afterthought! It's the balance thing which has prompted me to ask whether the motor is loose and not fastened down with the belt properly tensioned.

 

[Charles Lamont]

If you try to run up at top speed from stone cold, and the bearing adjustment is on the tight side, you can get the front spindle bearing binding. When this happens (don't do it too much or you may well make the bearing pick up, if it hasn't already), does the spindle feel stiff to turn by hand? Try running at 3rd from top (about 1000 rpm) for 5 minutes or so from cold before using top speed. If it is a real pain, try slackening the bearings adjustment a gnat's, but be aware that this will increase you chances of getting chatter. (btw, I had my Super 7 from new, over 40 years ago.)

Having watched the video again, it is pretty clear that this is what is happening, as the spindle stops momentarily about half way through.

 

[goldstar31]

I was trying to expand the information given so far. I have scrapped most of my notes when I downsized some years ago. One thing is that the Myford 'Blue Book' is for new lathes. Mine is not covered!

So with the loss of the old Myford firm, it is perhaps worth recording additional,information. My sketchy notes say 'Haythornthwaite.com' and I thought that the site would cover scraping in a Super 7 spindle. I was wrong but there is a write up of a factory overhaul with a mention! It is worth having. So is a recent write up( 14 pages or so) on the Homeworkshop.org site. The Haythornthwaite site does cover a large amount complementary information which is not confined to Super7's. Again, it is excellent stuff.

Somewhere is a write up of a cheap reconditioning of a ML7--- Postbag Model Engineer- more than 15 years ago. I'd like to read - what I wrote!

Norman

 

[don-tucker]

If you hold a stick on the bearing and the other end on your ear,you will soon pick up a noisy bearing,an old one but works
Don

 

[RobWilson]

Edit

Irrelevant to thread
Rob

 

[Swifty]

If you hold a stick on the bearing and the other end on your ear,you will soon pick up a noisy bearing,an old one but works
Don

Used a similar method over the years, but with a large screwdriver, just make sure that you put the handle end against your ear

Paul.

 

[Johnlukes]

Thanks for the feedback guys.
Some interesting points.. Yes incidentally there was grease in the myford oil gun, and it did leak after I replaced it with oil, but I have bought a very expensive replacement and the new one is very good and of course doesn't contain Grease. I haven't stripped anything down to remove any grease, but I changed the oil in the gearbox, and that was grease free.
The lathe spindle was a bit on the tight side when I bought the lathe, and I ordered a c spanner to slacken it off a bit, by the time this turned up though the spindle had slackened itself off and remains free spinning.
Charles I think that you may be close to the truth, as the problem fades into near insignificance when the lathe has warmed up, although it has nipped up a couple of times even when warm. Do you think that the bearings could be damaged?
Thanks again.
John

 

[goldstar31]

I sort of guessed about the grease. You were lucky, my gear box was dry-except for the mahogany dust.


So another question? Are you using Nuto 32 or more correctly ISO32 Hydraulic oil in the front bearing?
Lots of people are not- don't be offended. I once read that 'non hydraulic oils affected the bronze bearing' Frankly, I don't know but have chucked the comment in.

Meantime

Cheers

Norman

 

[Charles Lamont]

Do you think that the bearings could be damaged?
Thanks again.
John

Well, the bronze might have picked up on the shaft or there could be some scoring. You won't know if you don't look. On the other hand it is quite likely to be perfectly OK. Taking the spindle apart is not to be taken on lightly, but has to be well within an owner's capability for belt replacement. Don't forget to slacken the grubscrew that holds the bullwheel (I won't tell you how I know this). On reassembly, Myford's advice was to put quite a lot of preload on the angular contact bearings with the threaded collar at the end of the spindle. Also, position the bullwheel to limit the axial float of the pulley, otherwise you can get an annoying rattling noise from it oscillating.

 

[goldstar31]

Of course we are still guessing about the cause of the noise but here is something that my experience with Super7's has never come across. I've always had grey lathes and not the more exotic and modern green ones. Mine have always been drip ones with a sight glass showing the feed to the front bearing. So with the green one- is the oil getting through to the front bearing?

All that I know is that I was sold a wick- the wrong one.

Cheers

Norman

 

[Charles Lamont]

Early Super-7's had a big oil reservoir in the top of the headstock casting. I have never seen one of these, and don't know how it worked. Mine (grey) is like John's, having the later little oil cup at the front of the headstock. You are supposed to top this up daily (only once: even if the level goes down straight away, there is no need to refill). My experience is that before being filled at the start of the day the cup should be no more than half full, indicating that the oil is going somewhere.

 

[RichD]

That sounds like the thrust bearing. The one just inside the pulley on the countershaft. Its only under load when the spindle is being driven.

I second the guess. I was viewed the video and thought...thrust related. Then I saw this post.
Rich

 

[Charles Lamont]

No. The countershaft thrust bearing is only loaded when the clutch is disengaged. When engaged, all the axial thrust forces are internal to the rotating assembly.

 

[bb218]

When I watched the video about in the middle of the movie the spindle stopped and the belt squalled then the RPM went up. Did you shift the machine up ? Might try and put a little bar soap on the belt sides to make sure the belt is not causing the noise. Mike

 

[BaronJ]

No. The countershaft thrust bearing is only loaded when the clutch is disengaged. When engaged, all the axial thrust forces are internal to the rotating assembly.

Yes you are right ! I got it the wrong way round. My apologies. :wall:

 

[goldstar31]

When I watched the video about in the middle of the movie the spindle stopped and the belt squalled then the RPM went up. Did you shift the machine up ? Might try and put a little bar soap on the belt sides to make sure the belt is not causing the noise. Mike

Maybe the wrong Vee belts. They should be M 33.5 and A 29.5 per one Blue Book. Ah, well- and there is or was a school of thought about slack(ish) belts. In Thomas, I suspect.


Of course, Myford did change to a flat belt drive. Hemingwaykits have a kit to convert existing vee pulley configerations to flat belts. Less noise, smoother drives - or so they claim.

Norman