Noisy spindle bearings...

[John Hill]

...... I fear my 12x36 generic Chinese lathe (brother of the Chester Crusader) has developed a noisy spindle bearing. 

I have not decided what to do about it,  one option would be to reach for the plastic and buy another bearing,  or I could adjust the pre-load in the optimistic hope that that might fix it or I can just turn up the music level in the shop and forget about it.

This is a gear head lathe and has never been what one would call quiet.

[krv3000]

HI dont no if this my hellp but slacen every thing of and re pack the bering and see if that helps wher i once worked we got in a clarke lathe and after sum time the thing started to making a lot of noisy turnd out that ther was hardley any grees in the spindle berings ree packd them all ok onec a gane   

from bob

[Davo J]

Hi John,
I wouldn't think your bearings would be gone yet, mine are still going strong after 6-7 years.
I would take the spindle out and check the bearings for any damage then re install them with the correct pre load. There may be some grit or something that has got caught up in the drain holes.
These lathes rely on a splash feed where oil gets sprayed up on the top cover from the gears, then runs down the channels on the side of the head stock into a drain hole above each spindle bearing to lubricate them.

To take the spindle out you need to undo the spindle cover on the left hand side to get to the locking nuts and take off the one behind the spindle nose to get the front bearings out.
 
Over on the candle power forum there is some good pictures of inside and the spindle bearings, but you have to join to see the pictures.
Post 506
http://www.candlepowerforums.com/vb/showthread.php?216408-my-new-lathe-...-Precision-Matthews-12x36-...&p=3511647&viewfull=1#post3511647

Dave

[John Hill]

Thanks Davo,  So if I take the lock nut off the left hand end and that big ring looking thing behind/around the camlock mounting I can lift the spindle out onto the lathe? 

When I first changed the headstock oil the inside of the gearbox was in a pretty nasty looking shape with a lot of paint flaked off and floating around inside,  I washed out all I could but have often lain awake at night regretting I had not washed the bearings at the same time, scaring myself that there would have been grit attached to the paint.

I guess I can give the bearings a wash (in kero?) where they are if I can get the lock rings off to expose them...

[Davo J]

Hi John,
This is what the left end will look like.
Photo from Wills link above
 http://www.candlepowerforums.com/vb/showthread.php?216408-my-new-lathe-...-Precision-Matthews-12x36-...&p=3511647&viewfull=1#post3511647


I remembered reading a post a while back on Model engineer from Lathejack and he has an album here of the problems wrong with his lathe.
http://www.model-engineer.co.uk/albums/member_photo.asp?a=13378&p=225751
Here are some pictures of his bearing from a new lathe




As you can see his came with rusted bearing from the supplier.

Kero will be fine, but I think the spindle would be better out of the head stock and this will give you better access to see the bearings and check them over.
Dave

[Jonny]

If going to that extent why not change the bearings.

[John Hill]

Thanks Dave,  he made it all look so easy!

 I wonder what special tools I would need if I did the same?  Big bearing puller?

Jonny, pulling everything apart is a bit bigger enterprise than washing in situ but you are right once apart it would be not much more to replace any suspect bearings.

[Davo J]

I would at least take the spindle out clean and inspect the bearings. If they are still in good condition why would you replace them.
The left hand bearing should be a light press fit or a sliding fit as it needs to be this way to adjust pre load. To remove the spindle it should only need a few taps from a rubber hammer after undoing the two lock nuts. Once it is out there is no need to remove the right hand bearing unless it worn or pitted.
The gears on the shaft would need to be slid along the spindle as it's coming out.
They are large bearing and will probably cost up around $150 or more to replace.

Dave

[Jonny]

Easy way to tell slap it in highest gearing and revolve the spindle by hand. Feel for any notchyness or play.
Whats the surface finish like on X traverse if you plunge in 0.5 and 5mm.

If its paint thats soft comparitevely and would be compressed to nothing or pushed away.

One of my chinky mills became noisy, soon after serious play in quill. They only use cheap bearings.

[Bogstandard]

John,

If it ends up the rollers in the bearings are OK but it is the outer race that is damaged, you can in fact regrind them out to get a good working surface.

I had to get this done on my Atlas lathe as the outer races were a special shape, and of course megabucks.

When you come to do the pre-load, the amount taken out of the race is automatically accounted for.

Where a lot of people go wrong with these type of preloaded bearings, they use the machine as soon as it it turned on. For first of the day starts, or long periods during the day of inactivity, you should let the spindle run for at least a couple of minutes to let the spindle warm up, and so take off the pre-load by expansion of the spindle lengthways, otherwise you are trying to machine with maybe  'ratchety' bearings, plus, if you are working to very fine facing tolerances, you can find that those will wander all over the place until the spindle is warm. I think the average spindle growth is about 0.002" (0.05mm) between cold and warm.

First off, you should check your pre-load, if it has had too much applied, or it has tightened itself up (the usual cause), your spindle will never be able to expand enough to get rid of the ratcheting, and so, it might be giving the symptoms you describe.

Always look for the easy way out or fix first, if that doesn't work, try the next easiest steps until you eventually cure the problem. You should only start to panic when big bucks get involved.


John

[John Hill]

Thanks for the comments everyone.

John, I will check the preload as a first step.

With the machine in top cog, or between cogs, if I spin the chuck I can hear 'something' though it would be an exageration to say a 'rumble', certainly not like rusted trailer bearings!

It actually makes much more noise in the lower speeds and of course it is really noisy with the feed box engaged if the change gears are not carefully adjusted!

[doubletop]

John

If you are going for new bearings SKF have a useful online catalog with specs, drawings and even CAD components.

http://www.skf.com/portal/skf_nz/home/products?contentId=188739&lang=en

Unless you need them in a hurray its probably cheaper to buy them elsewhere. For some reason the NZ prices are way higher than getting them sent from offshore, even with the shipping cost.

Pete

[John Hill]

Thanks Pete,  I had another careful listen with a bit of wood against the housing, hand turning in a 'neutral' gear position.  The bearing certainly does sound munted.

[Chuck in E. TN]

Munted= Damaged, nackered, hosed, fubar.

Chuck in E. TN

[John Hill]

I thought today would be a good day to take a look at those spindle bearings....

It was only a few minutes to get the cover off the left hand bearing and to take the lid off the box, then I took out the four screws that hold the ring around the other end of the spindle.  Of course I had taken the chuck off but that ring does not come off over the D1-4 mount,  surely the mount does not come off the spindle

So back to the other end, I loosened the preload lock nuts, they were not very tight and required only minimal effort to loosen them.

Then I looked inside the box to see what would be required to slide the spindle out, there are a number of gears on the spindle which seem to be kept in place by one black metal ring which has two set screws, so I loosened them but the ring does not easily move.  So that was the end of any notions of being able to slide the spindle out or get a close look at the bearings.

Although the oil is up half way in the indicator window there was almost no oil in the one spindle bearing that I could see and none in the oil channel under the lid, so I tipped in a bit more oil so that the big gear on the spindle is now dipping the surface which should surely slosh it around a lot more.

I put the spindle nuts back on, the first one I did up fairly tight but it might not have even moved the bearing on the spindle and it certainly did not nip up the spindle at all, then the lock nut on behind it.

Of course it is still noisy but maybe not so noisy now that the bearings have oil.

Does anyone know what is required to get the gears off the spindle?

Thanks.

[John Hill]

Not having any clear information on how to safely remove and examine the spindles and bearings I decided to flush the bearings as much as possible while in situ and I made tools to do the preload adjustment.
 
 
 
I used the procedure in the Grizzly manual which is, induce clearance by wacking on the end of the spindle after loosening lock nuts then tighten while using a DTI until no further movement then a further 4mm turn of tightening.
 
 
 
Naturally enough it was not as simple as described and I was really glad I had taken the time to make tools for the job, a pin wrench to fit the spindle nose holes for the camlock and two 'C' spanners for the nuts.

wrenches by aardvark_akubra, on Flickr

It was easy enough to see the movement initially but at the point when movement ceased to be indicated I found I could still cause .01mm deflection just by pushing my hand against the end of the spindle, then I found I could cause the same deflection just by pushing on the headstock itself. The spindle turns quite freely and is somewhat quieter than I recall. Time to give it a run and watch for temperature rise.

[Bogstandard]

Now you have found the reason why you should never lean anywhere on your machine whilst using it.

It plays havoc when trying to cut to size.

I really do hope it works for you.

BTW, the Grizzly manuals are about the best ones I have seen, I downloaded 3 of them as they didn't have my exact machine, but ones that were close enough but having slightly different features on each one, and by looking at all three, I can get any info I want. My original one is only good enough for a**e fodder.


John

[John Hill]

John, the Grizzly manual seems to be for a machine of the same headstock but different feed gear box.  They did say to use a hammer and punch on the nuts if there was no C spanner, that would have surely have been a recipe for endless frustration....

The actual adjustment took all of 5 minutes but I do not know if it is tight enough and I certainly dont want overtight as that cast iron box looks extremely fragile when one puts what amounts to a 2 inch bolt with a fine thread nut through the middle of it.   I guess I will just give the nuts a little tweak until I can detect a temperature rise in the bearings.

I had to really raise the oil level completely above the sight window before the teeth of the spindle gear got to dip in the oil, so that might be something to think about as with the oil at the level of the sight glass there would have been very little oil getting thrown up for the main bearings when the lower gear box was not engaged.

John

[Bogstandard]

On mine John, with the oil to the sight glass line, I know that there is oil getting up there, as I have a very slight oil weep on the front bearing housing.

It's about the only time I was happy to see a leak.

I must have done a lot more work with my machine than you have, and there are no ill bearing sounds at all as of yet.

Mind you, Chester did give it a thorough going over before they sent it out to me, after the fiasco we had with the first one. Methinks they went over it with a fine tooth comb and made sure everything was set up perfect, as they knew I would be doing a very tight inspection of it as soon as it was in my shop.


John

[John Hill]

John, I know mine sat for several years in the showroom, in fact it looked quite shoddy when I bought it at a considerable discount.  I can see how corrosion damage (the shop is close to the sea) to the bearings could show up later as noise but until I can get a clear idea how to safely remove the spindle I will assume the improved oil supply and re setting the preload are the best course of action.

This is all complicated a bit in that I dont have real experience of this class of machinery and my hearing is quite poor, almost totally deaf in one ear and just a few frequency bands in the other.

[Davo J]

Hi John,
With the noise just starting recently I doubt it would be rust, sounds more like a bit of something that worked it's way into the bearing/s.
Good to hear you picked up on the oil level being too low.

Dave

[John Hill]

The good news is that after three attempts it all runs as advertised with a warm spindle after 20 minutes on the highest speed.  Plus I think it really is quieter than it was.

For anyone contemplating re-setting the preload on these lathes my advice is to acquire or take the time to make suitable tools and it would be a possibly long, frustrating, knuckle skinning process trying to do it without them.

[Davo J]

Good to hear you got it sorted without any major issues.

Dave