eBay linear bearing LM8UU

Hi folks,
something I've been wondering about. I was playing with a spare LM8UU from
eBay the other day and noticed that an inserted M8 shaft would wobble quite
a bit around the axis of the bearing. I went to purchase a "proper" one from
a local bearing supplier to compare but when quoted $60 for one changed my mind.

I was just wondering if anyone who knows a bit about bearings might be able
this wouldn't occur in "genuine" bearings but common to cr*ppy eBay ones.

Just trying to stop the wobble in my X axis carriage.


Many thanks

M8 is noticably smaller than 8mm in diameter.

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[www.bonkers.de]
[merlin-hotend.de]
[www.hackerspace-ffm.de]

Sorry, my mistake.
8mm

I suspect it can be pretty hit and miss. I've had good luck with cheap bearings, but at the price I think you probably need to accept you might get a bad set, or at least a bad example in a set.

I bought flanged bearings from [www.aliexpress.com] and they were good, and I bought 10 SC8UU from [www.aliexpress.com] and one of the ten had some play in it.

The longer ones(45mm) have less deviation, and better quality(smoother).

Edited 1 time(s). Last edit at 04/30/2016 10:05PM by MechaBits.

Its give and take. I have never had a big issue with wobble on them however I have had an issue with the straightness of my 8mm rods. Must consider that if this bearing is moving horizontal with respect to gravity then it should not wobble but slide just fine. If you are not satisfied there are 8mm sliders out there made of copper or brass that have graphite inserts that hold much better, however you can only use on chrome plated rods.

The copper/brass one sound nice. Where do they come from?

I found some linear bearing/way? on eBay but rather pricey.

With the stock stainless I bought, I had to order ten from the supplier
and check them when I picked them up. Gave about half back. Wasn't
a popular customer after that.