Lathe bearing lifetimes?

[Evanism]

Gday all,

A quick sort of question, I hope. I have a Cougar EVS250, which is an absolute cracker of a lathe. Tons of power.

No real issues, but I was turning a large number of spheres for the new family Christmas Tree and noticed a bit of growling coming from the bearings as I held the spheres in place.

I use a fairly simple jig of two chucks, each holding the equivalent of an egg cup. The tailstock one is mounted via a rather interesting doodad sold by Gary Pye (Tailstock Chuck Adaptor). I make it pretty tight to hold the sphere as I rotate it through the three requisite 90-degree machinings. (I love making them, really easy!)

Anyway, it gets away from me..... how long can one expect a set of bearings in the head stock to last? Is it reasonable to assume that they are big meaty thrust style bearings?

Is this something you worry about replacing after a few thousand hours of turning? If they are "groany" after only a short use, is this a cause of complaint/warranty?


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[dai sensei]

After short use, definitely a warrantee issue

[Woodturnerjosh]

Are you sure it's not the bearings in the adaptor for the chuck in the tailstock? I had a cheap live centre that the bearings died on and it made quite a bit of noise....Just a thought.

And no the bearings should last a lot longer than that! The headstock bearings should last for years and years especial if they are are tapered roller (I'm not sure what the cougar uses)

[Evanism]

The Live centre at the time was sold as being the bees knees. I recall the blurb. Having a stare at it shows me it uses 6202 double dust jacketed bearings, the good Japanese ones.(I have plenty in a tube "spare")

Gary Pyes website looks like its on holidays.... Nothing but a skeleton there.

My question was more towards how long I can expect them to last and whether they are regarded as user serviceable....it would seem not.

[oreos40]

It is possible that the center lines of the tailstock and headstock are not in line with each other. even though the points may line up when you check them they could be skewed. this would cause the cups to move slightly and cause a growl or chirp depending on the speed of the lathe.

[Woodturnerjosh]

Although off topic I have been thinking about replacing (if possible) the ball bearings in my live centres with angular contact ones. These would be more able to deal with axial thrust and most (if not all) metal lathe centres I use have this sort of set up for that reason.

Aaaand back to topic.

As I'm not sure what the lathe bearings are I can't comment on life span but my Vicmarc had tapered roller bearings which had a lot of use for a decade and where still fine. In that set up they were user serviceable (to re-grease if you felt the need) and easily replaceable if you have the right tools.

[Ron Rutter]

It is most likely the live center. Replacing with a deep groove ball bearing could be better, but angular misalignment would probably be more critical. Tapered roller bearings are used in pairs ( think car axle ). A 6202 is a small bearing but should stand up. I agree with the misalignment comment as a likely cause. If the bearing ( live center ) moves & feels OK under no load it is probably fine. Ron.

[hughie]

The Live centre at the time was sold as being the bees knees. I recall the blurb. Having a stare at it shows me it uses 6202 double dust jacketed bearings, the good Japanese ones.(I have plenty in a tube "spare")

Gary Pyes website looks like its on holidays.... Nothing but a skeleton there.

My question was more towards how long I can expect them to last and whether they are regarded as user serviceable....it would seem not.

No bearings are not user serviceable, when stuffed you replace them. 6202 if you had to buy are not expensive so dot worry about it. If you have noise somewhere definitely check the live centre, simply rotate it with your finger it be smooth, not grittiness and no sound. Too much side thrust ie massive end thrust will wear out the bearings on your live centre, from memory 6202 are not thrust bearings and that might be your problem, if so change em and dont worry any further.
Head stock bearings should last for years, I mean years and years and usually get replaced after abuse. I would think not many have ever changed headstock bearings on their lathe.

[Woodturnerjosh]

Yes, 6202 are just ball bearings. 7202 are angular contact bearings and are the same dimensions. I've only ever used larger non-sealed version of these in vertical motors so if you are going to try this it would be worth speaking to your bearing supplier.

[issatree]

Hi All,
I bought My " Tough Lathe " back in 1990, nearly always sits on 3000 Revs.
Have never had a problem with either Lathe or 2 T/Stock Live Centres, in all that time, which makes me wonder what some Turners are doing, to have this happen.

Must admit though, that I do remove the 2 plates on the H/S, to take the plastic covers off & use Molykote on the Bearings, but I haven't done it this year, so I had better grease them, just in case.
Also My Lathe has never ever lined up, T/S has always been out to the far side. Height is OK, but it has never worried me in all that time, & my work has alway been well above average.

[Oldgreybeard]

I have just replaced the H/S bearings in my Tehnatool 3000 (20 years old) These are sealed bearings and the problem was cuased by lack of use:oo: That's right, it sat unused for 10 years in a tin shed where temperatures in summer would have reached the high 40s or higher and the grease in the bearings had dried out.

New bearings cost $32.00 for the pair and replacment was quite simple although access to a hydraulic press is required to press out the old and press in the new.

Bob

[issatree]

Hi Bob,
A little different to the" Tough ", as they recommend in changing Bearings, that after removing all Grub Screws, bring up the Tail Stock, remove L/T/Centre, take a block of wood, put it between the Quill & the Spindle & wind the T/S Wheel & it pushes it out.
Not sure how you put it in, as I have never had to do it yet, but as I said in previous thread, I can get to the Bearings very easy , so as to grease them.

[Oldgreybeard]

The bearings were not only pressed in but also held with loctite.

The pressure gauge on the hydraulic press reached close to 15 tonne before the bearings moved when being pressed out - so I wouldn't recommend using the tailstock.

The bearings are sealed bearings and I am not aware of anyway they can be 'serviced'. I would be interested in your technique if you are repacking a sealed bearing.

Bob

[hughie]

The bearings were not only pressed in but also held with loctite.

The pressure gauge on the hydraulic press reached close to 15 tonne before the bearings moved when being pressed out - so I wouldn't recommend using the tailstock.

The bearings are sealed bearings and I am not aware of anyway they can be 'serviced'. I would be interested in your technique if you are repacking a sealed bearing.

Bob

In general terms bearings are packed with grease if they have seals both sides. The amount of grease will last as long as the bearing does. The danger with 'repacking sealed bearings' is too much will cause over heating and so end the life of the bearing. Given the price of bearings it would be smarter to just change the bearing.

Loctite and pressing is usually a indication of an over size bearing housing, hence the need for loctite. Either that or the bearings have been changed before by a previous owner.

[issatree]

Hi Bob,
To release Loctite, all you had to do was to add a bit of heat, say a Hot Air Gun, wood maybe have been the Solution.
Knew of a chap once, super glued the bearings in, but were not in the right place. Used a block of Hardwood & son was swing a 14lb. hammer. Released them after a long time.

[Oldgreybeard]

Hi Bob,
To release Loctite, all you had to do was to add a bit of heat, say a Hot Air Gun, wood maybe have been the Solution.
Knew of a chap once, super glued the bearings in, but were not in the right place. Used a block of Hardwood & son was swing a 14lb. hammer. Released them after a long time.

The above was tried without success using hot air gun at 450C. Bearing housing was not oversized - actually 0.015mm under the size of the bearing. Do not know why loctite was used, but the bearings which were replaced were the original bearings.

A 15min drive to the engineering shop to press the bearings out with the proper equipment vs risking damaging the H/S housing and / or the bearing housings was a "no brainer" so far as i was concerned.

Bob

[Woodturnerjosh]

Loctite stud lock and retaining compounds are very different things to the super glue and are much harder to remove. Having them properly pressed out is the safest option