Linear Profile Bearings - Clatter Noise, Maintenance?

[Tenson]

Hi guys,

I got some second hand 'SBC Linear' profile rails with bearings. Two of the bearings seem to run smoother than the other two. One is a bit worse than all the others. I've posted a video to show this, I hope you can hear the sound. The second bearing I move is the most noisy and I can feel it is a tiny bit less smooth, although mostly it is just sound.

Is there a maintenance procedure for this kind of thing? I don't want to drop all the ball out the bearing by not doing it right!


http://www.youtube.com/watch?v=tlILkqpygcw&feature=youtu.be

[Tenson]

Says 'SBG (S) 15' on the bearings so I think it's these ones - Welcome SBC Linear (http://www.sbclinear.co.kr/eng/s_syst/syst_1_3_1.php)

There is a little screw on one end of each bearing (grub screw looking), could it be adjustable pre-load? Other end looks like a lubrication point.

http://i608.photobucket.com/albums/tt169/tenson_uk/DSCF2077.jpg (http://s608.photobucket.com/user/tenson_uk/media/DSCF2077.jpg.html)

http://i608.photobucket.com/albums/tt169/tenson_uk/DSCF2076.jpg (http://s608.photobucket.com/user/tenson_uk/media/DSCF2076.jpg.html)

[EddyCurrent]

Does sound a bit noisy, I don't have experience of these type yet but with a normal bearing I would wash it out with white spirit or similar then regrease with the correct grease.
Maybe it's something on the end seals, you could remove those easily to see if the noise is still there.
I imagine if one or more balls are missing it could sound like that.

www.jena-tec.co.uk/downloads/linear-guides/sbg-range-linear-rail.pdf

[Tenson]

Oh that's good, how did you find the datasheet? Why does it Say Jena-tec? Is this a standard kind of rail / bearing construction that many people make exactly the same?

[JAZZCNC]

The grub screw is just a Blank for the grease nipple.

I have fitted loads of SBC rails/bearings and they are ok. They do have one little thing that can happen and I'm pretty sure this is what your problems is.?

The bearings have thin steel plates that helps retains the bearings and stops them falling out when off the rail. If not careful when fitting then these can get damaged, often it's because the ends of the rails have not been ground smooth or have sharp edges or just rough handling.
The bearings a have 4 ball runs 2 at top 2 at bottom the Top two runs have thin plate each side and the bottom 2 share a wide plate that sits in the bottom and rides just above the top surface of the rail.
It's this plate that gets damaged and when the balls roll over it makes that sound.

They are easy to strip and clean but do over a container has all the balls will fallout.

To strip remove the 2 tiny screws and the Grease nipple (you can leave the grub screw in) that hold the wiper seal covers, behind these you will find 2 Allen key bolts.
These hold the end caps onto the main bearing block. These end caps hold the thin steel covers in place and all the balls so when you remove all the balls will fall out so make sure your working over a container.
When you pull the end covers off they will have 4 tubes sticking out each cap, these hold the balls and form the circuit. If you carefull pull at them and hold the end cap you'll see they detach from the end cap.

Now you will be able to examine the thin steel plates for damage and clean everything. If you look carefully at the ends of thin steel plates and the inside of the end caps you'll see how the register to each other with slots in the end cap to hold in place.

To reassemble then put one end cap back on full.
Then put the tubes back in the other side but leave end cap off.
Next put the thin plates back into the registers on the fixed end cap.
Now while holding the thin plates roughly in place load the tubes with balls. For the wide thin plate I suggest you lightly grease the back side to help hold.
When tubes are fully loaded you may have a few spare balls, these go into the end caps held in place by grease.
Now put the end cap back on beaing careful to locate with thin plates and not drop a ball.!!! .. . . . Do all this over the conatiner.
Thats the bearing done.

When putting back on rail turn the bearing upside down so you can see the balls and watch that none get pushed out the race by the rail. They shouldn't but if your thin plates are damaged or worn then it can happen.!

Thats it and your back to together.

Will post a short vid when it's loaded up.

[Tenson]

Hi Jazz, thanks very much for the detailed reply. A video would be of great help as I'm no following all your descriptions (perhaps if I take it apart I will then follow better).

Do I just use standard lithium grease?

[JAZZCNC]

Hi Jazz, thanks very much for the detailed reply. A video would be of great help as I'm no following all your descriptions (perhaps if I take it apart I will then follow better).

Do I just use standard lithium grease?

yes just lithium grease will be fine.

Here's Vid SBC - YouTube (http://youtu.be/sWjzTWyck5k)

[Tenson]

Thanks so much :) I'll do it tomorrow in better light.

[EddyCurrent]

Also I suppose you have to wonder why they are second hand, were they knackered and they replaced them or was the equipment using them retired.

[JAZZCNC]

Also I suppose you have to wonder why they are second hand, were they knackered and they replaced them or was the equipment using them retired.

I've bought loads of used rails and mostly they are perfectly fine. Infact the X axis rails on my machine where Second hand 6yrs ago and they are still fine, an trust me i've abused them badly.
The Y & Z axis are SBC fitted new 6yrs ago and again run and abused in some pretty shity conditions and they are still like new with no signs of wear so i'd be very surprised if it's anything other than something simple like the plates.

Also realise These type of rails don't float on air like lots of people think or expect and they have a preload which can give the impression they are sticking or binding. Some noise is not unusual but this does sound like catching plates.

[Tenson]

Oh before I take it apart, do any of you happen to know the number of balls meant to be inside? The blocks measure about 61mm x 47mm.

[JAZZCNC]

Oh before I take it apart, do any of you happen to know the number of balls meant to be inside? The blocks measure about 61mm x 47mm.

Sorry can't help here not got any 15mm at the moment only 20 and they will probably have more balls or larger balls.? I've re-built the bearing now and haven't really got time to strip back down and count balls.

[Tenson]

Okay I took the worst sounding bearing apart, cleaned and re-assembled. Thanks for the help Jazz.

Sadly it seems just the same! I couldn't see any damage to the plates. Interestingly these bearings have no plastic tubes, see the image.

That said, it probably is to do with the plates as they quiet down with some weight on them, presumably pressing the balls onto the main body and keeping them off the plate edge.

http://i608.photobucket.com/albums/tt169/tenson_uk/DSCF2080.jpg (http://s608.photobucket.com/user/tenson_uk/media/DSCF2080.jpg.html)

http://i608.photobucket.com/albums/tt169/tenson_uk/DSCF2081.jpg (http://s608.photobucket.com/user/tenson_uk/media/DSCF2081.jpg.html)

http://i608.photobucket.com/albums/tt169/tenson_uk/DSCF2082.jpg (http://s608.photobucket.com/user/tenson_uk/media/DSCF2082.jpg.html)

[EddyCurrent]

So how many balls ? and did you compare that bearing with one of the other quieter ones ?

[JAZZCNC]

Sadly it seems just the same! I couldn't see any damage to the plates. Interestingly these bearings have no plastic tubes, see the image.

That said, it probably is to do with the plates as they quiet down with some weight on them, presumably pressing the balls onto the main body and keeping them off the plate edge.

Ok well this is not unusual but it does show they are older than 3yrs because for the last 3yrs every one i've used has the tubes. Before that they didn't.! Infact the latest ones the plates are actually fastened using little screws and can be removed without taking the end caps off.

Regards the weight making them quite down then again thats not unusal and they will move more freely also and take that notchy feel away.!

Honestly I wouldn't worry about it put them back together and use.!

[EddyCurrent]

Regards the weight making them quite down then again thats not unusal and they will move more freely also and take that notchy feel away.!

Good idea, if you have a decent set of weighing scales this might show a difference between the one you stripped down and one of the quieter ones.

[Tenson]

Well.. if you want to count the balls they are in that picture! I know it had the correct number because there were an equal number in each track and the gap between them was the same as the other smoother running bearing.

I'm not that worried now I know there is nothing clearly wrong. I'll get to using them.

[JAZZCNC]

Good idea, if you have a decent set of weighing scales this might show a difference between the one you stripped down and one of the quieter ones.

Really not worth the effort has they will be fine and besides there's very little can be done about it if they are worn out because the body will be worn not just the balls.!
Even if they are worn they will still be miles better than the cheap round rail bearings unless completely knackerd which they don't look or sound to me.