LH countershaft bearing getting v.hot on S7

Hello.

It seems that all I am posting lately are problems with my old S7 so before I launch into my post I would like to say that I am humbly very grateful for all the wise poster's patience and willingness to help me out. So here goes...

The other day my clutch cam lever started playing up and so I took the clutch assembly off for an investigation. However what I also found when putting everything back together was that when running, the LH oilite bush bearing was getting extremely hot especially when running in the faster of the two pulley ratios. First I thought this was because the bearing was old and a bit damaged so I replaced it.

However now having replaced the bush the problem is still there. Investigating whether the motor pulley/belt was pulled too tight I reduced the tension until the belt was wobbling like a silly thing - still there. Even when the countershaft cone pulley has been removed from the equation so it's not driving anything other than itself! When slack the countershaft rotates in the bearing very smoothly and is not overly stiff when taught either, so I am a bit lost! (the bearing is clean)

Has anyone got any suggestions as to what is going on? and is this an issue I should be worried about? I certainly don't want the swing head casting to start cracking!

Many thanks

Thomas, I sort of answered on the other thread, suggesting that the Oilite bush may be bunged up, and need cleaning(or replacing), and reloading with oil, I see you did replace it, did you soak it in oil before you inserted it, and does it have an oil supply, I don't know the Myford lathe.

Ian S C

Hello Ian,

Yes, the bush has a hole in it for an oil cup supply, so plenty of oil getting to it. I did not soak it in oil beforehand, I bought the bush from Myford direct so I assumed that it would already be loaded...

I'm not sure if this is relevant or not but the oil surface in the cup oscillates with the rotation of the shaft at high speeds (maybe a bubble..)

Hi Tom

When I last dealt with Oilite bushes ... many moons ago, I always soaked them in a oil bath overnight prior to installing, even to the extend that the oil could be warmed up to allow the bushing to expand ( being made of sintered Bronze ) to allow oil to permeate the bushing. Not being familiar with Myfords does the shaft have any form of oil trap incorporated? I doubt if Myfords would have bearings sat in an oil bath after machining. As I remember when replacing white metal bearings on turbines, even though being pressure fed lubrication systems there was always an oil trap in them either on the bottom of the bearing or the horns were relieved to trap oil, mainly too provide the initial film of lubrication ( oil wedge) on start up... Just a thought

George

We used to fill them by placeing a thumb on the bottom of the bearing fill with oil and press your other thumb on top you could see the oil weep thigh the sides.

Are the shaft motor ,lay shaft and spindle truly parallel , and the pullies in line.

You can get the lay shaft twisted in relation to the spindle

Stuart

Edited By Lordedmond on 03/11/2014 15:37:22

It may be possible to get it hard faced by an an agricultural welding shop or a press tool maker.

Mike

Edited By Michael Poole on 03/11/2014 16:55:09

IJust to add to the above i it possible there maybe a little to much load on it due to belt being to tight !

H

George - yes the there is an oil cup feeding the bush through a hole in the bush.

Spoke to Myford. They said it was a good idea to soak the bush first. They also suggested reaming the bush to the exact 7/8" but I am not keen on that as it surely would smear the pores (although this may have already happened!!). Also, it is not stiff when slipping over the shaft so I can't see that it's necessary.

They then suggested it could be something pulling down on vee pulley as it was only the LH bearing getting hot and I should check the belt tension (Harry - see first post, this doesn't seem to change anything) and alignment which corresponds with what Stuart is saying. Although when running for a test, only the countershaft was fitted with it connected to the motor pulleys, so no race bearings & circlip or even the cone pulley to tension to the spindle. So I am not sure in what dimension the mis-alignment would be to cause such a fuss, because as soon as its running it self aligns in most directions and there is no wobble on the vee-pulley. Although I agree I can see that this could be the cause.

Michael - sorry, not sure what you mean here.

Going to bang it out again tonight and stick in my oil can and hope for the best

I don't have a S7 so cannot advise directly Thomas - however I've always understood that you shouldn't try to machine (or ream) Oilite bearings - but I think you know this already.

Whenever I have a problem like this on my older machines (especially after I've been working on them) my first reaction is always to step back (e.g. strip things back down) and do a visual and "touch" check (fingers can be remarkably sensitive test instruments) for anything that just seems 'wrong'. From what you've said - you did this but...

Quite often - I've done something daft which is usually easy to spot and remedy. If not, then I'd reassemble as carefully as possible (in single steps - one thing at a time) and check things as I go along. Sorry if this sounds like "teaching Granny egg sucking" but you seem to have only started having problems after stripping your clutch unit and re-assembling it. I strip my older machines quite a bit - and if something isn't quite right afterwards, it's usually something I've done.

Do you still have the old bearings - and are they 'handed' for instance - what happens if you swop them over? It's silly things like this that often cause me problems. If it was working - and isn't now - what did I do to change it?

Quite often it's something fairly simple/obvious but I'm afraid to admit that sometimes it takes me quite a while to spot it.

Regards,

IanT

Hi Thomas,

My post about the hard facing was supposed to reply to your question about the worn clutch cam.

Mike

The Oilite bush should be loose on the shaft before insertion, the housing it fits in will compress it to the right size. It is normal to insert the bush with a mandrel, a bit that goes through the bush should be the size of the shaft, and polished, then a step in the mandrel to press the bush in, make sure it presses in square, if not you can scrape metal off the side of the bush.

I can't remember the interferance fit for these bushes.

Ian S C

Hi Thomas,

Is the clutch slipping? even with no load, it might still slip with the drag and generate heat which will transfer to the shaft bearing block, on the left hand side. The reason I mention this, is that your woes appeared to start with you fixing the clutch engagement mechanism.

Is/has the end float in the clutch mechanism (0.010 inch) been set correctly after your repair? not easy, as I could not see how to get a feeler gauge in there! I set the end float by just leaving a bit of detectable slop in the clutch lever, when the clutch is engaged. As far as I understand, the small ball bearing and spring in the end of the cam follower (the subject of your other post) act as an anti-rattle device, taking up the end-float.

Regards

Phil

Hi

Details for machining oilite bearings can be found here though it does state that it should be avoided if possible which supports the general consensus of opinions here. That said there is no mention, as far as I have seen from a quick scan, of reaming so this might be best avoided totally for the reasons given by those with more experience in the above posts. The slightly worrying thing is that Myford have recommended this as a possible solution !!??

Regards

Martin

Edited By Martin W on 04/11/2014 11:38:26

Martin

I agree do not ream oilite , As to " Myford " now they are not and never will be the Myford of old ,I would not trust there advice at all they do not have the know how about the lathes nor do they have the information regarding what part fit what , I will stop now for fear of the mods axe

All I will say is " caveat emptor "

Stuart

Btw my big bore LH counter shaft bearing runs warmer than the RH one

IanT - very good advice, don't worry you are not teaching me to suck eggs - I'm still pretty new to this hobby. I think this is the first thing I will try.

Michael - ah I see, thank you.

Ian SC - Yes, the bush is loose on both the shaft and in the cast housing - so the housing is not compressing it. I have been loctiting the bush in place to prevent it rotating in the housing - although I haven't tried just leaving it to do it's thing yet. I have been fitting the bush with the countershaft in place so I know it's aligned with the RH side.

Phil - No, the clutch itself wasn't slipping it was the cam lever creeping back to the engaged position (scary huh?). Found out that this was due to the previous owner assembling the cam follower backwards so the steel ball had no hole to recess into - thus gouging the cam lever.

Martin - Thans for the links. So regarding machining or reaming, it seems that this is an option - although "should be avoided whenever possible". I am really hoping I can avoid this as I don't think my skill is up to a level that is required here (not yet anyway). If  have seen mention of reaming elsewhere as well as here https://www.oilite.com/PDFs/castBronze_designData.pdf. but it said it had to be extremely sharp!

I would like to say that Myford were very pleasant and helpful over the phone giving me two call backs to discuss the problem - I have no reason to discredit them.

Thanks for the advice guys. The bush is currently soaking in Nuto 32 and I hope to continue my investigations tonight.

Edited By Thomas Gude on 04/11/2014 13:12:33

Hmm...

You didn't "bang it in" in the first place did you? If so you could have distorted it. As Ian pointed out, they should be inserted (and removed) using a stepped mandrel. It's best to make up a puller using a bit of tube and some studding.

Russell.

No it just slipped in - hence the loctite. Do you think I've fudged it? Had to bang the old one out also.

I suppose the real question is what will happen if I just let it get hot? Will the cast housing crack? Will the steel countershaft wear? Will only the bush wear?

It only gets very hot on the faster of the two stepped pulley speeds and I do not use this very often.

Thomas

Something is wrong here. Don't know about myford but if a plain oilite bush is running hot , it is not tight inside or out and is getting plenty of oil, then some other force is the culprit. I don't know what, but if someone with a bit of experience looked at it then it might well get sorted. BTW I've never seen oilite bush on a c/shaft, my old one just had cheap plummer blocks and ran for years.

Surely if you coat the bush with loctite it will prevent oil penetrating the Oilit bush. hence the bearing will be running dry and will then heat up. The bush should be a press fit in the housing, Not glued in. just my thoughts for what they are worth

Mike you beat me to it we now have a Loctite filled oilite bush instead of a oil filled oilite bush . Not the best situation ,time for a new bush me thinks

Stuart