Tuning Up Cheap Chinese Linear Bearing 

They should send the components disassembled to save on assembly cost

You have a choice...Either "Cosmoline" to protect it from corrosion and rust...Or it starts rusting as it takes three or so weeks to cross the pond and the salt air permeates the shipping container. It's an easy choice. And truthfully, you should always clean your parts and do a good TI before assembly anyway.

Thanks for taking the time to share your findings. This is archive-grade work which will serve many people for years to come. I am collecting information on how to make a better router - the 8x12” I built a year ago was to get my feet wet, and this is the kind of information I need to achieve the results I’m after.

Lots of good information here. Thanks for the thorough explanation and procedures. It really is night and day when you take the time to thoroughly clean these. One thing that I have noticed works very well with these inexpensive rails is to purchase higher quality ball bearings and swap them out. It's a $5-8 fix that can dramatically tightens up tolerances and spherical geometry.

Thanks for this video. In all my googling for improving Chinese linear rail performance, I've not come accross such a complete video. I'd figured some parts for myself, but tightning the screws on the sweeper AFTER putting the block back on the rail never crossed my mind!

Hiwin rails will have the same kind of drag when you receive them, but they'll wear in and slide easily after running for a bit of time

Remember to not mix carriages between rails and dont take all balls from all cariages at once. It's often happen in cheap guides that balls have diferent sizes depending on tolerance dimention that rail and cariage were made.

People like you make videos that are very useful and educational. Not like the one who wants cheap stuff but complains of quality problems and makes the content drop the manufacturer. If it has been given lubricant then the liener will not be easily shifted by gravity, it is different because of the inherent lubricant properties.

HiWin must be thrilled to see these guys using their company colours.

I dont have any linear rails yet, but when I get them, I'm definitely following your guide. Much appreciated!

i used rubbing alch and a sonic cleaner to get all the metal grit out of a set of these! it worked pretty well

Nicely Done. I Enjoyed the Level of Detail & the Explaination of all the "failure modes" / Things that can be wrong with MGN type bearings. Subscribed.

Another thing to be careful of is the end of the rail where it was cut in the factory. The cheap ones may have sharp edges at the very end where it was cut, so there might be a slight lip right where the bearings slot into. I put one bearing on my rail before removing any sharp edges or burrs at the end of the rail, and that seems to have put a small nick in one of the bearings so it has a small flat causing a lot of noise. I used a wire brush to smooth the edge of the cut, and the 2nd bearing was just fine.

I knew nothing about this subject (linear rails - cleaning linear bearings) before the video, now I know ;) Very helpful, Thanks ;) (3D Printer related interest)

Thanks for sharing. My linear rails slide like a dream now

Thanks! I feel a lot better about going for the cheaper rails now that I know they can work well with a little TLC.

Very very very well done video. Now I know how a linear bearing is supposed to work and how it is made and how to fix it in case.

Cleans components, proceeds to file directly over them.

Thank you good sir for the wonderful video! Got mine running like a champ now!

Thank you for the tip... now I am going to buy linear bearing for my next project :)

Wow! I just bought a Felder Jointer/Planer machine that uses 2 Hiwin Linear rails and blocks; and a number of the balls fell on the floor when I was putting the blocks on the rails. I have spent 2 days trying to find something on this malady. Thank Jesus I found you; and you did a great job of explaining of how to make these work right. So I must purchase some balls and replace them; and of course follow your tips. Thank you so very much kind Sir.

I used brake cleaner to degrease my hiwin bearing. Also works great.

Nice video and interesting comments. Thanks all round.

I try to avoid using magnets with ball bearings and stuff like that, nothing worse than fuzzy balls after you accidentally magnetize em. Probably not a big deal if you don't produce a lot of steel dust but for me at least, its such a pain

This is exactly what I was looking for. Nice concise video.

This is great , i got some super cheap rails on ebay for fun. and they to had nasty shipping grease all over them. but may i suggest instead of using a magnetic tray ( bearing balls can interfere with one another if there magnetized ) lay a towel out on your work bench, this will catch everything without the chance of it rolling away.

"What do you mean, those can move by their own weight alone?" *mind -> blown*

awesome tips, Thank you for sharing

great video, straight to the point and very informative!

Really good video, im just about to try this on a china Special linear rail - thank you

Many thanx, will do the same procedure, and i hope it will works.

Excellent tutorial . Thanks!

Excellent video well explained thanks ….

Great info. I just bought some (supposedly) ultra-high quality HIWIN rails (very expensive), and they were binding exactly like you show here right from the factory. Also covered in grease, just like shown. I'm going to rebuild them today.

this is a very useful video, thanks for sharing. I wish this has been around before I put everything together haha

Excellent helped alot other day at work

10/10 best way to clean your balls. and rail blocks.

Many thanks, useful video and most important for me at the time :)

Thanks this video was really useful, fixed my problem with a set I recently purchased on AliExpress that were a bit crunchy. After cleaning I looked at the bottom of the cleaning solution to find some fine metal particles plus other particles I couldn't identify. I found white spirits did a better cleaning job than alcohol and water.

really nice...now i am not afraid to buy cheap bearings from aliexpress

Amazing description! Very curious about the one i ordered!

Brilliant just what I was looking for I’ve ordered 3 heavy duty sets to make a good CNC may I just say another video a guy measured the bearings and they were all very slightly smaller and as quality bearing are minimal cost he recommender replacing them which I’ll do also

Great detailed instructions. I couldn't figure out how to remove the guides so I put the damn thing back together and blasted it with half can of DW40, blasted it with warm air and then applied a bit of 3in1 Silicon lubricant. So far so good. BTW my rails didn't have that extra plastic problem

Great job and great guide you are right wd40 should only be used for loosening off stuff and nothing else. you did a very good job on these :)

very helpful vid, thank you!

I was an FC 2010 to 2016 just got into 3d printing this year..

Really useful thank you.

Lovely video. Thank you. I just received what may be precisely the same rails. Thing is, I’m not sure the resistance will matter very much. I’d love to see a before and after cleaning print.

always good to clean them no matter where they come from not just from china ones, the reason is they add lubrication is because they dont know when it will be sold or where its going to be stored in and for how long period till it gets sold....so it coats it so that in any condition they have them at who ever bought them to sell well if they have them stored with to much humidity then things wont corrode and rust ....but for sure you need to clean any of those you buy from anywhere and add your own lubrication after the cleaning.

I didn't thought it wouldn't be that of a difference! Espacially just after cleaning them up. How "good" is the tolerance? 🤔

Hooyah brother - great instructional.

Just cleaned up a few after watching this. Cleaning it is key too!

Hi that's great, you know how to revise the end cap for getting smooth movement and saving money on upgrade your 3D printer. 👍

in my HIWIN MGN12 linear rails were total 62 steelballs.

Very good video thank you

i saw these on ebay when i was looking for parts for my diy pcb mill. was curious if they were any good. i think many of the mechanical thingstuffs i get from china all come with packing grease that needs to be stripped off and replaced with something more usable as a lubricant.

Very cool video except I use eucalyptus oil to remove the factory residue.

And if you then want some accuracy in this rails you can change the steelballs into some 2.381 g10 quality balls. they are cheap and absolutly accurate like the hiwin ones! I build myself an mini-mill and my accuracy is about 0.03 mm at aluminium

I was so upset , now I know what should I do thank you

Do this without disassembly: Soak entire assembly in iso solution, then place in sealed container with silica desiccant beads. Basically my go to process for any Chinese oil coated junk.

Very helpful.

Thanks for sharing, looking into getting some 800mm linear guides for my Delta printer. Kind of curious since its been nearly two years. How well are these holding up for you?

Thanks for posting this. I was always afraid to look at the linear bearings that came on my 3D printer but after seeing you reassemble yours I'm confident I'd be able to line up and reinsert the balls if I ever need to :). One observation - the tube of bearing grease that came with my printer is a lot thicker than the oil you're using. It's about the same consistency and stiffness as vaseline. My rails run smooth and are a quieter than the ones you show in the video - could it be that they'd benefit from a thicker lubricant than you're using? I think I hear metal-to-metal contact in your vid (both on the stock and the re-lubed rails). Perhaps the pressure of the balls is breaking through the oil film and making that noise - maybe a thick grease specifically for ball-bearings is a better choice? Sure they run with less resistance with a light oil like you're using - but I believe they'll be noisier and wear out faster. Also, viscous oil adds damping, which helps cancel out vibrations and ringing in the surface of your prints so a thicker oil might improve print quality at high speeds.

Dude this is great

THANK YOU!

Very nice.

it is a great help

What could cause it to still be binding after you've cleaned and put it back together. I had no gaps of any kind between bearings, almost as if there were too many. Mine tried to pop out more than once while putting it back on the bar. Tip of my exact got magnetized sitting in the little tray and that helped put them back in. It's a fiddly thing for sure.

Very descriptive and useful - thanks! @3.55 - you're filing plastics parts down in your cleaned parts cup. I was wondering why you didn't use the magnetic pan/cup with the water/alcohol solution - any specific reason?, the parts ought to stay down there and not easily fall out and dissapear on the floor, and no need to move them around too much - getting (more) finger grease on them when clean, etc.

EDIT: THANKS a lot for this video :) I just tried to do this on the rails I got. They look exactly the same, but even after two cycles of cleaning, bending the guide wires so they don't press the balls too tightly against the race and de- and regreasing, two of my rails are still quite hard to move. did you have success with every pair of rails you ordered? I feel one of mine has just a little bittoo tight tolerances...

Lovely and smooth, makes you wonder why the chinese fill them with so much junk... I watched a similar video using 'skateboard' (radial) bearings.

Just found seven on the floor, thought I was only missing SIX !!!!

Wicked video. my friend shelled out on Hiwin rails because of all the bad reviews on the cheap Chinese rails

For lubrication is great "mobilgrease xph 222".

Excellent video but I was wondering, couldn't you submerge the bearing without disassembly into the alcohol and have it dissolve the gunk? Move it back and forth while submerged for a bit? And could I use acetone in lieu of alcohol? Thanks!

I also ordered some cheap rails and I have one question. Are little scratches on top of rail an issue? Sides where guides/balls should roll look good.

Is disassembling them necessary for cleaning them? I have a similar set on my printer and I got mine oiled with a basic (non-silicone) oil directly on the rails and I've never had any issues.

Nice video, thank you! Just a caveat about WD-40. Don't use it to "lubricate". It is not a "penetrating type lubricant" but actually a degreaser and water displacer.

I do that with my LM8UU linear bearings as well..usually they come with grit/garbage in the small bear bearings and cause issues and alot of noise.. I would bet a drop of non-detergent air compressor oil would go a LONG way in the smoothness of that rail and bearings

A good quality fishing reel oil would work also.

MENTION: the green plastic parts can also be further separated in two parts each and properly cleaned.

Why don't you use mineral spirits or naphtha? That works VERY VERY well. Relube with a lubricant appropriate for your application.

You can also purchase new loose ball bearings with a better grade, G25 or better and make these rails run better.

Be careful when using the water and isopropyl alcohol mixture, it can rust the balls (crappy steel). Happened to me and I had to order new ones to replace the original.

I have bought 2 extra MGN12H blocks because there comes only 1 with the rail. When i place them on the rail, they don't even slide a bit. I need some force to move them over the rail. So, i hope i can fix them, else, i have to trash them.

interesting bud thanks for sharing - although I must admit I think I would feel more comfortable spending the extra money on the quality part if buying them individually.

:starts filing the plastic exactly above the parts he just cleaned for debris ;) anyway thank you for sharing. now i know what to do with my rails and bearings ;)

wtf is with everyone complaining about using wd40? he used slick50.. slick50 is really good stuff!. people need to start paying attention.. Thanks for this video!

Do you think you could just soak the bearings in your solution without disassembling them and still get similar results?

Type of lubrication is dependent on a few factors. Speed is the main one. The faster you want something moving, the lighter the lube must be. (Less resistance) Type of surface is secondary. Two flat plains as in a lathe bedway and anything with ball bearings have different needs. The lathe will use a much thicker lube to keep everything in place. Load plays a slight factor, too. As mentioned, sewing machine oil is great for these tiny, light load linear rails. SAE10 to SAE20 is what I would recommend. Something with no detergents, a.k.a. compressor oil. qurl.org/PnV Engine oils are not recommended. They will suffice for a short while but you will notice a film grow on your components(the soaps being oxidized) and eventually the ball bearings get choppy again.

I bought a used 3D printer with these linear bearings. They worked like garbage so I followed your video. Upon pulling the blocks off I realize that the previous owner must have removed those wire guides. I made new ones out of guitar string (wire). I was able to resurrect 2 of the 3 blocks but the 3rd is probably a lost cause. There may be bearings out of round or something. It works better with less bearings and gets too tight to slide well when the full complement of bearings is on board.

Great mate i like it , have you understand what is the difference between MGN12H and MGN12C ?

Wow nice solid 3D printer base, is it for sale?

Not sure if you're still responding to comments on this, but does it make sense to replace the balls in these with ceramic balls? Obviously that puts you with not cheap rails anymore, but theoretically, you should never have to perform any maintenance again right? No lubrication would be the least amount of drag too if that makes any difference.

Are you still satisfied from those rails on working? Are they performing well on your machine?

sweet!

Do you think you could use contact cleaner to clean this decently without disassembling?

My problem was the size of the balls. I had to measure one by one and take out the big and smaller ones

Please what's the series of the bearing block you're cleaning?

But are the rails nice and true? Is there any play on the bearing housing block? Cause thats the problem with cheap rail bearings, they aren’t true no matter how smoothly they move. I would like to see how far off the rails and the block is when it’s moves along the rails.