Author Topic: Any idea why this lathe is chattering? Spindle bearings? (Read 26709 times)

loply · « **on:** January 02, 2016, 12:06:02 PM »

Hi folks,

Video showing the problem - shot of the surface finish is at the end -

So I've just finished doing a full refurb on this lathe, scraped it all in, replaced the old gear drive with a direct belt drive & VFD, serviced all the parts etc.

Put it back together and it's chattering like mad. Anything steel above about 30mm is more or less unturnable, and even on steel around 15mm it only turns nicely if I use a high rake tool (like what you'd use on aluminium). It seems like it just can't handle a heavy load.

I've double checked everything and eliminated all obvious variables - tried different bits of stock, steel, alu, all different tools etc. Checked nothing is wobbling on the saddle/slides/etc. Absolutely everything I've eliminated I think.

The chattering noise is coming from the headstock. The poor surface finish does not improve the closer to the chuck it is. The bearings I adjusted tighter and tighter but that didn't help. I have about 0.007mm of end play in the spindle (if I chuck up a big bar and pull on it).

I'm wondering if the bearings are knackered? They're timken taper rollers and the races look okay to a laymans eye, but I don't know for sure how to test them?

Would appreciate any advice as I'm a bit disappointed at this stage!

Thanks,
Rich

John Swift · « **Reply #1 on:** January 02, 2016, 12:12:29 PM »

may be not enough pre-load on the spindle bearings
excessive overhang of the tool and play in the gibs will add to the problem
try using a centre to support the end of the bar
if the chuck jaws are slightly bell mouthed it would not help having so long a piece unsupported

John
PS
having another look at the video the tool length is not the problem

loply · « **Reply #2 on:** January 02, 2016, 12:53:56 PM »

As I say I tightened the spindle bearings a lot and it didn't really help. The official spec is for no preload on them.

Had the part chucked tight as hell though as I say the problem happens even right next to the chuck so I don't think it's a workholding / rigidity issue.

Arbalist · « **Reply #3 on:** January 02, 2016, 01:18:16 PM »

What type of tool is that you're using, it's difficult to make out for sure.

loply · « **Reply #4 on:** January 02, 2016, 01:22:22 PM »

Tried everything - all the same result - two types of carbide insert, HSS, really sharp HSS, and sharp brazed carbide...

Best results came from tools with big back rake - like 35 degrees - but these won't last on steel. Still could only take 3 or 4 thou without chattering.

jb3cx · « **Reply #5 on:** January 02, 2016, 01:27:36 PM »

I think I would agree with john about using a back centre ,and try different speeds ,that's a fair lump of Steel hanging out of the chuck
Peter

Pete. · « **Reply #6 on:** January 02, 2016, 01:28:30 PM »

Put a DTI on the chuck and wrench the bar up and down. If it moves the DTI your problem is in the bearings. Where did you get the spec for the pre-load? My 280 is set by running the lathe at high speed and measuring the headstock temps.

Arbalist · « **Reply #7 on:** January 02, 2016, 01:52:12 PM »

Quote from: loply on January 02, 2016, 01:22:22 PM

Tried everything - all the same result - two types of carbide insert, HSS, really sharp HSS, and sharp brazed carbide...

Best results came from tools with big back rake - like 35 degrees - but these won't last on steel. Still could only take 3 or 4 thou without chattering.

But what is the tool in the video?!

chipenter · « **Reply #8 on:** January 02, 2016, 01:58:01 PM »

I recently had to scrape my compound slide to my toolpost . as there was a gap at the front of about 1 thou made a big diference to the finish .

SteveT · « **Reply #9 on:** January 02, 2016, 02:51:53 PM »

Looking at your video the chatter is uniform along the length of the bar, and the tool looks like its about 10mm wide and flat to the cutting surface the tool should have a clearance rake so you are only cutting at the tip.

1/ have you assembled the taper bearings correctly I think they should be back to back? also depending on the bearings set-up are the bearings cross located
that is the bearing assembly needs space to expand as it heats up, a common fault on newly assembled bearing units is the shims are but in the incorrect place
so locking the bearings.

2/ From the video the lath sounds very rough which points to the head bearings

If you could post an assemble drawing of the head it would help a lot.

Hope this helps

RussellT · « **Reply #10 on:** January 02, 2016, 02:58:27 PM »

I haven't watched the video but it might also be worth checking the fit of the chuck to the spindle nose - a bit of swarf could cause this sort of problem.

Is this the original or the spare headstock.

Russell

Arbalist · « **Reply #11 on:** January 02, 2016, 03:23:36 PM »

Quote from: SteveT on January 02, 2016, 02:51:53 PM

The tool looks like its about 10mm wide and flat to the cutting surface the tool should have a clearance rake so you are only cutting at the tip.

That's what I was thinking. I'm also unsure about the height of the tool as well.

DavidA · « **Reply #12 on:** January 02, 2016, 03:31:34 PM »

Loply,

According to the manual for my 280 Synchro there should be no end float at all.

It instructs one to adjust the preload but not to allow excessive heat to be generated in the bearings.

it reads...

The machine should run at top speed and the bearings should not exceed 65 C.

that may be your problem; loose taper bearings.

Dave.

hermetic · « **Reply #13 on:** January 02, 2016, 04:02:08 PM »

To sum up everyones comments! The bar is far too long and large to be not supported at the outer end., the tool angle is far too obtuse, I don't think the cutter is on centre height, and the machine speed is too fast, and also there is probably some flex in the QCTP. Watch doubleboosts early videos on youtube using a similar lathe. Then put a centre in the bar and support with the tailstock centre, re sharpen the tool, set on centre height. Slow down the lathe, and slow down the feed, and that should cure the problem

loply · « **Reply #14 on:** January 02, 2016, 05:46:55 PM »

Hi guys,

Thanks for all the advice. I appreciate all the comments although some of them have missed some of my original points.

Regarding the spindle bearings, if I grab a long bar e.g. the 50mm x 150mm piece of steel in the video, I can deflect it's ends up or down about 0.03mm quite easily with just a bit of hand pressure. I've no idea whether that's normal or not as I've never tried it on another lathe before. Could somebody else confirm what they get on their lathe for a similar size bar?

If I put a really sensitive indicator on a ground MT3 test bar and spin it by hand, the needle does jump around randomly a bit. The indicator has increments of 0.002mm (ie about a tenth). It doesn't run out by a consistent amount. That might just be normal though as the indicator is so sensitive. With a normal 0.01mm indicator it looks pretty smooth.

I initially had no preload on the bearings, then gradually tightened them until I couldn't move the nuts any tighter with an 8 inch spanner. Strangely the bearing friction didn't increase noticeably. They don't seem to be getting hot when ran at full speed though I can only check by touching the casting.

I will double check the chuck-spindle connection carefully, that is a good point, thanks. I did have the chucks on and off quite a few times today mind and it was the same each time, maybe there is a ding in the thread which I didn't notice though.

To address some of the points which I don't think are relevant (though I could always be wrong!) -

The workpiece isn't the issue, the bar is a traditional size for a test bar, ie 50mm steel bar 150mm long, so it's only sticking out by 3x it's diameter, no need for tailstock support. Indeed that would defeat the entire point since it's meant for testing the headstock alignment. This is a fairly normal test you would do on any lathe of this size (albeit often with two 'collars' by relieving the middle somewhat). Besides which the chatter occurs even right next to the chuck so it's nothing to do with the length of the workpiece.

The tool is also irrelevant, it does the same with any type of tool. In the video it's a high back rake HSS tool - about 12 degrees on all sides but about 20 on the back rake, and razor sharp. Same thing happens on carbide inserts and brazed carbide. The exact same tools on my previous lathe cut perfectly. Definitely on center by the way - checked that several times and tried slightly above and below too just out of desperation. I get better performance with really high back rake (like 30+ degrees) but that shouldn't be necessary.

I tried two different chucks too by the way, a 4 jaw and the 3 jaw in the video. Cranked both of them really tight to be sure.

Cheers,
Rich

loply · « **Reply #15 on:** January 02, 2016, 06:05:01 PM »

By the way the depth of cut in the video is 0.06mm, that's all it can manage, any more and I think it's dangerous (sounds like it might rip the part out).

For RPM, tried everything from about 150 with HSS up to about 800 with carbide, and everything in between. Couldn't find a sweet spot anywhere.

awemawson · « **Reply #16 on:** January 02, 2016, 06:09:27 PM »

I wonder if the bearing adjustment isn't working quite as you think? If you are swinging on an 8" spanner I'd expect some noticeable friction and them running warm. Indeed in the past I've adjusted head stocks so that there is just a bit of noticeable friction, then backed them off a tad. Leave them running while having your tea, and if they are not warm when you return they are too loose. If you can't keep your hand on them they are too hot and need a slight slackening.

Crude. But it works.

philf · « **Reply #17 on:** January 02, 2016, 06:12:12 PM »

Loply,

Is there a sleeve over the spindle between the inner races of the taper rollers?

If there is you might just be tightening up against the sleeve and no amount of effort on the spanner will make any difference.

Phil.

loply · « **Reply #18 on:** January 02, 2016, 06:18:28 PM »

Hi Phil,

Nope, no sleeve. I know what you mean. It's just a simple bearing-spindle-bearing arrangement though.

Awemason, I am a bit perplexed as to why tightening the bearings so much isn't increasing the drag noticeably. I literally can't tighten them any more and they're only just dragging. I know the way it's built inside out though and there's nothing complicated about it. The only thing I could think is that the rear bearing is stuck on a ding on the spindle so won't move, but I gave it that much force I don't think that's likely.

Just been out and checked something, it's actually about 0.07mm up or down I can deflect the bar by, and I notice the chuck also moves - by about 0.03mm up or down.

I'll check whether the spindle nose itself can be deflected tomorrow, too late to start taking it apart now though.

DavidA · « **Reply #19 on:** January 02, 2016, 06:29:39 PM »

Loply,

...Hi Phil,

Nope, no sleeve. I know what you mean. It's just a simple bearing-spindle-bearing arrangement though.

Are you quite sure about this ?

I have in front of me the machine manual for the 280 Synchro, which also has two taper roller bearings on the spindle at the chuck end of the headstock.

There does appear to be a spacer in between the two outer rings.

Dave.

loply · « **Reply #20 on:** January 02, 2016, 06:42:03 PM »

Hi DavidA, absolutely positive. Had the whole thing apart no more than a few days ago, plus, I have a complete spare spindle + headstock sitting on my workbench

Unfortunately it has no bearings so I can't compare or use it...

The 280 is a lot more complex and has more bearings (plus I think a taper spindle nose?). They're much better machines I think. The threaded spindle nose is a real weakspot.

These older lathes only have one bearing in the front and one in the rear. Originally there would have been a sleeve on the spindle but it purely carried some gears - it wasn't a bearing spacer - but it's gone anyway as I have a taperlock pulley on there now instead.

Here's a video - the more I think about it, this definitely doesn't seem normal? I'm pushing quite hard mind. I'd appreciate it if anybody else could make a similar check on their lathe.

DavidA · « **Reply #21 on:** January 02, 2016, 06:46:21 PM »

Loply,

You are correct, they are very different.

Hope you get it sorted. i am still having teething problems with my 280.

Anyway, if all else fails, ask the company. They are still there and will probably be happy to advise you.

http://website.denford.ltd.uk

Dave.

PK · « **Reply #22 on:** January 02, 2016, 06:54:58 PM »

Do both bearings have the same ID? If not, could there be a shoulder on the spindle the rear bearing is hitting before it loads up against the headstock. (yes this is a stupid question, my experience in these things is that my own mistakes are often illuminated by them).

Pete. · « **Reply #23 on:** January 02, 2016, 06:55:54 PM »

Quote from: loply on January 02, 2016, 05:46:55 PM

Hi guys,

Thanks for all the advice. I appreciate all the comments although some of them have missed some of my original points.

Regarding the spindle bearings, if I grab a long bar e.g. the 50mm x 150mm piece of steel in the video, I can deflect it's ends up or down about 0.03mm quite easily with just a bit of hand pressure. I've no idea whether that's normal or not as I've never tried it on another lathe before. Could somebody else confirm what they get on their lathe for a similar size bar?

If I put a really sensitive indicator on a ground MT3 test bar and spin it by hand, the needle does jump around randomly a bit. The indicator has increments of 0.002mm (ie about a tenth). It doesn't run out by a consistent amount. That might just be normal though as the indicator is so sensitive. With a normal 0.01mm indicator it looks pretty smooth.

I initially had no preload on the bearings, then gradually tightened them until I couldn't move the nuts any tighter with an 8 inch spanner. Strangely the bearing friction didn't increase noticeably. They don't seem to be getting hot when ran at full speed though I can only check by touching the casting.

I will double check the chuck-spindle connection carefully, that is a good point, thanks. I did have the chucks on and off quite a few times today mind and it was the same each time, maybe there is a ding in the thread which I didn't notice though.

To address some of the points which I don't think are relevant (though I could always be wrong!) -

The workpiece isn't the issue, the bar is a traditional size for a test bar, ie 50mm steel bar 150mm long, so it's only sticking out by 3x it's diameter, no need for tailstock support. Indeed that would defeat the entire point since it's meant for testing the headstock alignment. This is a fairly normal test you would do on any lathe of this size (albeit often with two 'collars' by relieving the middle somewhat). Besides which the chatter occurs even right next to the chuck so it's nothing to do with the length of the workpiece.

The tool is also irrelevant, it does the same with any type of tool. In the video it's a high back rake HSS tool - about 12 degrees on all sides but about 20 on the back rake, and razor sharp. Same thing happens on carbide inserts and brazed carbide. The exact same tools on my previous lathe cut perfectly. Definitely on center by the way - checked that several times and tried slightly above and below too just out of desperation. I get better performance with really high back rake (like 30+ degrees) but that shouldn't be necessary.

I tried two different chucks too by the way, a 4 jaw and the 3 jaw in the video. Cranked both of them really tight to be sure.

Cheers,
Rich

1 thou up and down on the spindle is miles too much. I think you have a problem with your spindle fitment, borne out by the fact that as above you should be able to bind the spindle with heavy adjustment.

Have you got a photo of the spindle assembly out of the headstock?

loply · « **Reply #24 on:** January 02, 2016, 07:00:49 PM »

PK, I understand what you mean, but no, the spindle is one diameter where the rear bearing is, with no shoulder.

I've just been out and took the chuck off to eliminate the chuck:spindle connection. I can move the spindle up and down by about 0.01mm by pushing hard with my fingers on a 200mm long bar in the spindle taper. Again I don't know whether that's normal or not?

SteveT · « **Reply #25 on:** January 03, 2016, 04:08:27 AM »

In a past post you commented that you dropped the head, if you have a crack in the casting your would be able to set up the bearing okay but under load would get the reported chatter.
Worth checking I think .

Fergus OMore · « **Reply #26 on:** January 03, 2016, 06:50:34 AM »

At the risk of being very wrong, might I pen a few thoughts? Going back to the beginning of getting your Boxford, did you ever test it under power to do precisely what you are doing now? Or did you buy a 'basket case', scrape it or whatever? None of us ( ?) have that information.

It may well be that your spindle/headstock assembly was either worn or incomplete. Could you inform of this, please?

Regards

Norman

hermetic · « **Reply #27 on:** January 03, 2016, 08:22:10 AM »

if you did put a tailstock centre in, and the situation immediately improves, you will have proved it IS the spiundle bearings.

loply · « **Reply #28 on:** January 03, 2016, 11:09:32 AM »

Hi guys,

Fergus - I did test it before I launched my little rebuild, and it was similar to now, ie chattered a lot.

Steve - yup, I'm concious of that, I can't see any cracks but if I do order new bearings I will fit them to the spare head just in case.

Doc - when you say the chuck is 'sprung' what do you mean sorry? Are you referring the the jaws not being parallel?

So I've just been out and done some more tests. I managed to tighten the spindle bearings more by extending the spanners to give me more leverage, I think the rear bearing is too tight a fit on the spindle, as it took a lot of force, but doing so has reduced the end play to half a thou and got rid of the bearing noise. Also, it has introduced a bit of drag and for the first time the bearings are getting warm.... I can still deflect the spindle nose by about 0.01mm by pushing on a 200mm test bar though.

However, I think I've got to the main cause of the issue. The chuck just isn't rigid on the spindle nose.

I confirmed the shoulder on the spindle nose (which the chuck butts up against) is running true, and has no burrs, nor does the back of the chuck where it hits this shoulder, but the chuck body can easily be deflected up and down by several thou just by pushing on a 6" workpiece.

Putting a tailstock centre in makes it turn perfectly, I can suddenly take a 1mm cut on a steel bar and get a good finish.

The issue seems to be therefore that the workpiece is wobbling because the chuck isn't rigid on the spindle.

I checked the chuck was bolted tight to it's back plate, and inspected the spindle threads really carefully, can't see what the problem is though

Surely if the chuck is butted tight up against a true-running shoulder on the spindle, and there are no burrs, it should be tight and rigid? Unless it's just the small amount of deflection in the bearings being amplified?

chipenter · « **Reply #29 on:** January 03, 2016, 11:20:56 AM »

what the problem is though

Surely if the chuck is butted tight up against a true-running shoulder on the spindle, and there are no burrs, it should be tight and rigid? Unless it's just the small amount of deflection in the bearings being amplified? or is it butting up agains't the end of the threads somthing else to check .

SteveT · « **Reply #30 on:** January 03, 2016, 11:28:22 AM »

Sounds like you are getting close to the problem

but I note your comment that the back support bearing is tight on the spindle, in my last post I mentioned cross location i.e the spindle and bearing have no room to expand so preventing free expansion of the bearing arrangement. The back bearing should be a light transition fit on the shaft or the housing, if that back bearing is locked in position you can have a multitude of problems including short bearing life.

philf · « **Reply #31 on:** January 03, 2016, 11:41:04 AM »

Quote from: SteveT on January 03, 2016, 11:28:22 AM

e... in my last post I mentioned cross location i.e the spindle and bearing have no room to expand so preventing free expansion of the bearing arrangement. The back bearing should be a light transition fit on the shaft or the housing...

Steve,

The normal arrangement of two taper rollers is fail-safe in that, as the spindle expands with the heat, the inner races move apart thus increasing clearance.

I agree the rear bearing shouldn't be a tight fit on the spindle.

Phil.

Fergus OMore · « **Reply #32 on:** January 03, 2016, 11:50:03 AM »

Apologies but I may be quoting the obvious but a screwed to spindle chuck does not depend on the thread but to the register- or the backplate if there is no register.

Cheers

Norman

seadog · « **Reply #33 on:** January 03, 2016, 11:56:24 AM »

I was in the middle of posting a reply, but beaten to it by Norman. The regsiter on the spindle must be identical to the opening in the backplate. The thread is just to hold it onto the spindle.

loply · « **Reply #34 on:** January 03, 2016, 12:14:43 PM »

Thanks for all the input guys, few more things to check.

I don't suppose somebody with a similar sized lathe could chuck up a 6 inch bar, put an indicator on the chuck body and see how much the chuck deflects by when pressing by hand on the end of the bar?

John Rudd · « **Reply #35 on:** January 03, 2016, 12:21:16 PM »

Quote from: philf

The normal arrangement of two taper rollers is fail-safe in that, as the spindle expands with the heat, the inner races move apart thus increasing clearance.

I agree the rear bearing shouldn't be a tight fit on the spindle.

Phil.

As Phil says.......
The inner races on both bearings should be a good fit without being too tight else you wont be able to set the bearing pre load correctly

bertie_bassett · « **Reply #36 on:** January 03, 2016, 02:20:13 PM »

Quote from: loply on January 03, 2016, 12:14:43 PM

Thanks for all the input guys, few more things to check.

I don't suppose somebody with a similar sized lathe could chuck up a 6 inch bar, put an indicator on the chuck body and see how much the chuck deflects by when pressing by hand on the end of the bar?

I can see what I get on my viceroy tomorrow if I get a chance, mine needs a lot off attention but does actually turn out fairly good work.

have also got nearly all the drawing for the 4.5 and 5'' lathes, might take some digging to fine the headstock drawings but I'm sure they are there somewhere

loply · « **Reply #37 on:** January 03, 2016, 02:27:47 PM »

Thanks mate, would really appreciate that.

rotorhead · « **Reply #38 on:** January 03, 2016, 09:14:13 PM »

Hi loply,

I helped my son dismantle his Viceroy a long while ago, unfortunately I've forgotten its configuration, but I did download some original files from Denford, I'll include them for you.

If these are helpful I'll see what else I've got..

DavidA · « **Reply #39 on:** January 04, 2016, 07:17:05 AM »

Loply,

Have you joined the Denford machine forum ?

If not, you should. I just registered and there is a whole lot of stuff on all their machines. You could save yourself a lot of grief by going to the people who are using the same machine as you.

I can't think why I didn't do it sooner.

Dave.

p.s. check your PM.

bertie_bassett · « **Reply #40 on:** January 04, 2016, 12:08:40 PM »

with a bit of bar about 6 inches or so hanging out my chuck I can read about 1 thou of deflection on the side of the chuck, if I pull fairly hard toward me. that's on a badly maintained viceroy tds

id second joining the denford forum, loads of info on the site. a member there called dazz did a full strip down of his a few years back including a vsd conversion. pics are still there I think
plus they have all the original drawings

loply · « **Reply #41 on:** January 04, 2016, 04:11:46 PM »

Thanks for that Bertie. I'm getting about 2 thou in the same situation, just pushing hard with the fingers of one hand.

I presume you took the reading off the end of the chuck nearest the tailstock?

I might just go ahead and try some new bearings out of interest as much as anything. Seems about £45 for a pair.

As far as I can tell the bearings fitted aren't high precision or anything, just standard timkens as used on wheels and other things.

bertie_bassett · « **Reply #42 on:** January 05, 2016, 05:23:14 AM »

sorry ment to add a pic of my set up but forgot

as you can hopefully see I was measuring between the headstock casting and the rear end of the chuck. pushing quite hard wit my hand I was getting 1 thou deflection either way.

things to note though: iv never adjusted the preload on this lathe, its got fairly thick grease in it and takes a little while to get up to speed when cold. the chuck jaws are definitely belled out, generally in need of an overhaul.

loply · « **Reply #43 on:** January 05, 2016, 01:55:09 PM »

Success

Thanks for all the advice folks, think I've got this sorted.

I ordered some new spindle bearings which gave me the confidence to go to town on tightening the old ones. As I mentioned earlier, the rear bearing is a stupidly tight fit on the spindle - instead of a sliding fit like my other Viceroy, it's a tight press fit (presumably a factory error?).

I put a 2ft extension bar on the spanner and cranked down on the rear bearing nut... nothing for a while, then crack, it turned an eighth or so... Half expecting that I'd cracked the casting I checked it, ran it for a while, then tried again... Literally giving it all my muscle, in fear of knocking the lathe over if I slipped, it moved another eighth or so. I backed the nut off then snugged it back up hand tight.

End play disappeared completely, and play on the spindle nose came down to about 0.001mm (down by a factor of ten). The bearings are getting pretty hot but I can keep my hand on them (although not by much). The chuck is still deflecting though not quite as much (but it doesn't seem to matter).

On that exact same steel bar from the first video I can now take a 0.4mm deep cut without a single bit of chatter! Turning 100% parallel too... 0.00mm taper in 4 inches.

Couldn't be happier! The lathe is now performing exactly as I'd hoped. Thanks for all the advice everyone.

Video - this is at 1800rpm, 0.4mm DOC -

awemawson · « **Reply #44 on:** January 05, 2016, 02:05:37 PM »

Excellent news

Always good to hear of a satisfactory conclusion to these things

lordedmond · « **Reply #45 on:** January 05, 2016, 02:42:26 PM »

If the bearing get to hot slack the nut off a hair ,with a hide mallet give it a clout on the end opposite the chuck to move the spindle in a little to take off the pre load a little.

But if it was me , but it's your lathe I would take out the spindle and polish the journal so the bearing is a rightish slip fit then you will be able to set it up easier

Anyway glad you have it sorted a cheap laser temp gun is handy look for 20 to 25 degrees C above ambient as a guide

Stuart

Pete. · « **Reply #46 on:** January 05, 2016, 02:46:26 PM »

If the bearings are getting hot that should ease the pre-load though it's not an ideal situation. To release some of the load I would back off the clamp nut until it's loose, spin it up until barely touching and put a piece of soft ally flat across the back of the spindle then give it a good hard crack with a large ball-pein hammer. Either that or extract the spindle and clean up the bearing diameter a bit to ease the fit.

Now you mention it I recall the (floating) rear bearing on my machine was really tight on the spindle too.

DavidA · « **Reply #47 on:** January 05, 2016, 03:34:20 PM »

All this hammering on the bearings sounds rather brutal to me.

Surely best to remove the spindle and fix it properly.

Dave.

John Rudd · « **Reply #48 on:** January 05, 2016, 03:39:51 PM »

Well I did say, the bearing inner races ought to be a tight sliding fit on the spindle

I've changed standard bearings to tapers on several machines....to find I had to polish the journals to ensure a good fit.....no hammer used or big spanners to set pre load....

Excessive tightening will cause the bearings to overheat....but you know that already...

If you have changed a wheel bearing on a car you will know what I mean...

DavidA · « **Reply #49 on:** January 05, 2016, 04:05:27 PM »

John,

The front wheel bearings on rear-wheel drive cars is a good example,

I also have changed many of these taper roller assemblies. Th inner part (inner race) being a light interference fit, and the outer part just slides onto the stub axle.

And just nipped up with a enough force to stop the play on the wheel.

No brutality needed.

Dave.

bertie_bassett · « **Reply #50 on:** January 05, 2016, 04:55:38 PM »

glad you got it all sorted in the end

Pete. · « **Reply #51 on:** January 05, 2016, 05:08:18 PM »

Quote from: DavidA on January 05, 2016, 03:34:20 PM

All this hammering on the bearings sounds rather brutal to me.

Surely best to remove the spindle and fix it properly.

Dave.

You're right it isn't ideal but the bearings have already been run loose and had an awful shock from recent tightening up. I guess the answer is to install the new bearings and make sure they aren't such a tight fit so they adjust properly.

lordedmond · « **Reply #52 on:** January 06, 2016, 02:23:23 AM »

Pete

Bearings are tougher than you think in this case they may be K already , think of the pounding they take on a car / truck etc.

I think it's on the SKF site but may be Barden but they demonstrate fitting AC spindle bearings the a nylon tool and a hammer , yes it only put force on the inner or outer race as needed not both.

In this case the as I posted the spindle should be attended to , but I fear the OP will now have the devil of a job getting it off

Stuart

John Rudd · « **Reply #53 on:** January 06, 2016, 07:17:33 AM »

Quote from: Stuart on January 06, 2016, 02:23:23 AM

In this case the as I posted the spindle should be attended to , but I fear the OP will now have the devil of a job getting it off

Stuart

Where there's a will there's a way......angle grinder ready...

lordedmond · « **Reply #54 on:** January 06, 2016, 10:11:49 AM »

When we had a bad bearing let's say about a 10 inch shaft with it stuck in the cartridge housing ( big electric motors ) we fetched in one of the boiler makers , now I have never seen this done since I left the firm , but he used a normal welding torch not a cutter and manually manipulated the oxy to cut .
He could take of the inner raceway and leave the shaft in marked.

Now these we had to fit using go no gauges and heat to get them on

Those were the days

Stuart

Ps found the fitting guide from SKF with hammer
http://www.skf.com/uk/products/maintenance-products/mechanical-tools-for-mounting-and-dismounting/bearing-fitting-tools/bearing-fitting-tool-kits/index.html

loply · « **Reply #55 on:** January 06, 2016, 10:17:22 AM »

Believe it or not I used a 14lb sledge hammer to remove the spindle on this lathe last time.

That sounds brutal but it's actually not - Rest the smooth head of a smaller hammer against the spindle's rear, and a very slow swing of the 14lber just nudges the spindle out. It's more like a push than a sharp blow.

This is done with the head off the bed of course. Whacking it hard with a light hammer wouldn't work and feels more likely to do damage, but a slow moving unstoppable weight gets it out fairly easily.

Tried a 3 leg puller but I couldn't get the legs to hold on well enough. Obviously a proper press would be better, but needs must...

John Rudd · « **Reply #56 on:** January 06, 2016, 11:05:11 AM »

Respect to you Loply....

I think most folk would have gone ahead and used brute force after attempts with a puller....
Its far easier just to bray something rather than sit down and take stock and think.....

Just to add, my comments re the tightness of the bearings werent meant as a criticism or a ' told you so...' But more to be helpful with constructive comment....

sparky961 · « **Reply #57 on:** January 06, 2016, 11:06:14 AM »

I hate to admit this, for fear of looking less impressive next time I do it... but cleanly cutting one piece of metal off another is easier than it looks. The secret? Get in quick, get lots of localized heat QUICK and as soon as its hot enough, hit it with the O2. Get out as quick as you got in. Takes some balls on really expensive stuff though.

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Author Topic: Any idea why this lathe is chattering? Spindle bearings? (Read 26709 times)

lordedmond

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