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Where to get quality lm8uu linear bearings

Posted by Nikki81 
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Nikki81
Where to get quality lm8uu linear bearings
May 13, 2015 06:23AM
Where is the best place for me to get some quality lm8uu linear bearings. The cheap eBay Chinese ones I have used have already started to fail angry smiley

Thanks Nikki
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milkypostman
Re: Where to get quality lm8uu linear bearings
May 13, 2015 04:10PM
I'd be interested to try something like [www.igus.com] or [www.lulzbot.com]
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milkypostman
Re: Where to get quality lm8uu linear bearings
May 13, 2015 04:11PM
oh, but to answer your question, misumi has those bearings but they get expensive when you're not buying the cheap ones.
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Nikki81
Re: Where to get quality lm8uu linear bearings
May 13, 2015 04:44PM
Thanks they are expensive I'll have to save up and pack the ones I've got with grease till then
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milkypostman
Re: Where to get quality lm8uu linear bearings
May 13, 2015 04:58PM
are you actually having issues with them? I have actually found that while the bearings are cheap and one of my z bearings actually lost a bunch of the actual bearing balls, they run fine. they are a bit noisy to me.

I am wondering if I were to take them off, try to actually remove the balls, if they would run better.

The only thing I am noticing is some ripples in the side, but I actually think that is from my belt not being tight enough.
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Nikki81
Re: Where to get quality lm8uu linear bearings
May 14, 2015 11:23AM
Yes there where making a grinding sound. I stripped one down last night and one of the balls had a flat side on it !
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milkypostman
Re: Where to get quality lm8uu linear bearings
May 14, 2015 01:17PM
sigh, that's probably happening to me as well. i wonder if it would make sense to just open them up and remove the balls altogether. i am having a similar experience.
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gordonendersby
Re: Where to get quality lm8uu linear bearings
May 14, 2015 03:52PM
I also managed to wear grooves into my x-axis smooth rods with cheap lm8uu bearings.
Even using lythium grease from first fitting.

Gordon

Gordon
Currently have a tweaked mendel prusa i2
About to build a P3Steel.
[scratchpad.thisandthose.org]

Printer for hire.
[www.3dhubs.com]

Member of South London Makerspace:
[southlondonmakerspace.org]
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AquaticsLive
Re: Where to get quality lm8uu linear bearings
May 14, 2015 05:33PM
I use some from McMaster-Carr. Little pricey though. LINK
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milkypostman
Re: Where to get quality lm8uu linear bearings
May 14, 2015 05:43PM
tempted to try these: [www.thingiverse.com]
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alan richard
Re: Where to get quality lm8uu linear bearings
May 15, 2015 04:36PM
I think taking the balls out will make them wobble too much.

Take them apart and find a flattened ball - It would be worth just trying to source quality bearing balls. Sure they'd work out cheaper and its the balls that are doing the work.

I'd be dubious of printed ones but I can't say for sure.

This would be a useful thread to keep updated with results. I've had some terrible quality bearing units (but cheap)

-a
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o_lampe
Re: Where to get quality lm8uu linear bearings
May 16, 2015 02:27AM
Maybe the slotted adjustable linear BB is the right answer?

On the bay I could also find HQ balls to replace the crappy chinese ones.
Maybe worth to dig for ceramic balls? They can run without grease and have the lowest friction.

-Olaf
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the_digital_dentist
Re: Where to get quality lm8uu linear bearings
May 16, 2015 06:43AM
Quote
gordonendersby
I also managed to wear grooves into my x-axis smooth rods with cheap lm8uu bearings.
Even using lythium grease from first fitting.

Gordon

If you're wearing grooves into the rods its because the rods are not made for ball bearings. Ball bearings require a hardened surface or they WILL chew grooves into it.

Unfortunately, the market is awash in low quality rods and bearings made for people who are trying to build cheap 3D printers. Here's what appears to be a quality bearing at a reasonable price: [www.ebay.com] and the catalog page on them: [uk.misumi-ec.com] It isn't a drop in replacement for an LM8UU, so you'll probably have to redesign some parts for your printer to make them work, but that's exactly what a 3D printer is good for- customization. They will need hardened rods...
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o_lampe
Re: Where to get quality lm8uu linear bearings
May 16, 2015 11:39AM
Probably it´s a good idea to turn the steel rods a few degrees on regular base? That way they´d last longer, I´d say.

What do you think?
-Olaf
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the_digital_dentist
Re: Where to get quality lm8uu linear bearings
May 16, 2015 01:05PM
I think it would be better to get properly hardened rods. Then the whole thing will live longer than you will.
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Vanbot
Re: Where to get quality lm8uu linear bearings
May 18, 2015 01:58PM
I was planning on greasing mine but then realised that will prevent the balls in the bearing from spinning freely. I used some light oil meant for skate bearings and it has made them much quieter. Tinkerine uses brass bushings in some spots on its printers. Bushings require regular lubrication but they also seem to be much quieter and, on the Tinkerine anyway, certainly don't negatively affect performance.

When I was assembling mine the manual mentioned that linear bearings need to be aligned before they are fixed in place. I didn't know what that referred to at the time but now I've realised it means that you want to rotate the bearing on the smooth shaft so that there are two rows of balls resting on top of the rod. If you don't do this there's a chance it'll sit on just one row which will make it less stable and noisier/rougher. I marked the "top" of my bearings with sharpie so I know how to align them before I tighten the zip ties.
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isolt
Re: Where to get quality lm8uu linear bearings
May 18, 2015 04:42PM
milkypostman
I got some of those Igus ones and the matching extruded rods.
Although they say "Dimensions correspond to the standard for recirculating ball bearings " they aren't talking about LM8UU unfortunately.
So mine are still sitting on the shelf.
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milkypostman
Re: Where to get quality lm8uu linear bearings
May 18, 2015 05:06PM
yes, from the specs, the inside should be 8mm, but the outer radius and the length are off. Outer radius is 15 (lmu) vs 16 (igus) and 24 (lmu) vs 25 (igus).
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CraigMoberg
Re: Where to get quality lm8uu linear bearings
May 28, 2015 04:38AM
Quote
milkypostman
they get expensive when you're not buying the cheap ones.

Didn't Yogi Berra say something like that? winking smiley

Quote
milkypostman
I am wondering if I were to take them off, try to actually remove the balls, if they would run better.

The balls are what make the bearing, as in "ball bearing." They provide the minimum surface contact -- the tangent of a sphere -- rolling rather than sliding across a surface, to drastically reduce friction. That's what lets the carriage move smoothly along the rods. Removing the balls from a cheaply made or defective bearing would be like removing your tire because it's flat, and driving on the rim.
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thetazzbot
Re: Where to get quality lm8uu linear bearings
May 28, 2015 11:58PM
Or something like these

printed lm8uu

Thats my listing btw. Not advertising but just making a suggestion. Anyone here with a working printer can print these, but for folks sourcing bearings for new build, its a cost effective solution. And they work wonders... Btw they take about 3 hours a dozen to print, im using HIPS ar .2mm layer height
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milkypostman
Re: Where to get quality lm8uu linear bearings
May 29, 2015 12:20AM
is there a link to this design to print ourselves? I like the spacing on these. Have you tried with PLA?
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elwood127
Re: Where to get quality lm8uu linear bearings
May 29, 2015 01:59AM
I spent about 2 hours looking for bearings. Some as high as $40.00. Can't just buy them. They want to give quotes. German companies are awesome but pricy. There IS a difference in quality.
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o_lampe
Re: Where to get quality lm8uu linear bearings
May 29, 2015 02:41AM
I printed a few different bearings from thingiverse, but found, they bind too much on the rod. I only have PLA.
I printed rescaled samples in 99, 100, 101% size to see which would work best.
Unfortunately, I have a halfshell bushing that doesn´t support the bearing completely.

Now I´m back to the metall ones. Just bought another dozend and selected "good" from bad.
-Olaf
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Tinpau
Re: Where to get quality lm8uu linear bearings
May 29, 2015 10:41PM
I looked on the Igus site and saw that they would send samples. I ordered some samples in the sizes and types I wanted. I listed that I needed 4 of one size and they sent me 4, So it maybe worth a try to get a sample and try them.
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thetazzbot
Re: Where to get quality lm8uu linear bearings
May 30, 2015 12:41AM
Quote
milkypostman
is there a link to this design to print ourselves? I like the spacing on these. Have you tried with PLA?

If you have a Prusa style cartesian printer, use these for the X and Z axis:

[www.thingiverse.com]

Use these for the Y axis

[www.thingiverse.com]

Use PLA, PET, or HIPS. Don't use ABS. You can use abs but they will wear quickly.

NYLON would be ideal...

Edited 2 time(s). Last edit at 05/30/2015 12:43AM by thetazzbot.
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JamesK
Re: Where to get quality lm8uu linear bearings
May 31, 2015 11:23AM
Has anyone tried the graphite lubed bronze bushings? (e.g. [www.aliexpress.com] )
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epicepee
Re: Where to get quality lm8uu linear bearings
June 09, 2015 12:43AM
I haven't tried the bushings, but Makerbots use them, so they can't be too awful of an idea. One nice thing is that bronze is softer than steel, so at worst the bushing dies -- not the rod.
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madmike8
Re: Where to get quality lm8uu linear bearings
June 09, 2015 10:07AM
I use bronze bushings, and love them... I print an adapter that matches the standard LMxUU bearings dimensions that the bushings press into. I use standard size rods and bushings since im in the U.S. I use 5/16" for 8mm, and 3/8" for 10mm. You can pick up the bushings and rods pretty cheap through Fastenal or Servocity.
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isolt
Re: Where to get quality lm8uu linear bearings
June 24, 2015 04:29PM
Looks like the IGUS bearings are also designed as a press fit. They're pretty sloppy by themselves.

Edited 1 time(s). Last edit at 06/24/2015 04:31PM by isolt.
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691175002
Re: Where to get quality lm8uu linear bearings
June 24, 2015 06:47PM
The standard misumi 8mm bearing is 5$ a pop which really isn't that bad. I'm sure their quality is top notch, everything they sell is pretty good.

You may have to swap out the shafts as well though, linear bearings are very sensitive to shaft diameter and I'm not sure what the tolerances are like on imports.

Edited 1 time(s). Last edit at 06/24/2015 06:47PM by 691175002.
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