Easy RepRap - 12 LM8UU Linear Bearings for 3D Printer. Prusa Mendel, reprap

Pretty hit-or-miss in terms of how many of them will suddenly start feeling like they're full of sand. I slid one along a hardened, chrome steel guide rod one day and it abruptly started wanting to twist in a spiral as it moved. Shortly after that, several bits of bearing, or whatever passes for them, fell out. I'm using them on a 3D printer, where they're not under much load at all. I've had several fail or start dragging really badly at random. They'd be smooth as glass for several days and suddenly seize up solid. I guess you get what you pay for. I'll probably be shopping for something better.

These bearings started out great, but less and 80 hrs later they began to leak and squeak. Still work, but no printing at night while the wife sleeps. Irratic sound seems like an intruder in the house. not appropriate if white noise is not your friend.

These are great bearings. I use them for robotics projects. Initially I had all sorts of issues with them when moving them fast, the balls felt like they were grabbing instead of running smoothly. I researched the web and found a link to how to lubricate linear bearings and that site said use dry lubricant. Let me tell you DO NOT use dry lubricant. That is for linear bearings without the balls.I found a manufacturer's website and they explained why you should use an oil like: 3-in-1 oil. Apply the oil to the inside of the bearing and boy are they smooth.

But not have a good quality plastic, if the steel linear bar is a little little more small than 8mm the bearings jump out of bearing, if choose use it lubricate bearings and not play with this before put in linear bar, the bearings are very fragile

They worked alright but I had several lose ball bearings when installing the rods and they were very noisy. They work for inexpensive bearings but I have since moved on to Igus plastic bushings and the WAF (wife approval factor) went up a lot.

I'm using these with 5/16 stainless steel rod (US replacement for 8mm). These work, however do produce some noise and are not always as smooth as they could be. I'm sure they could be made much better, at probably a much higher cost.

they arent the best bearings, not the worst either...about half of them popped a bearing right away, the others slide decent, only three are what id call great quality.

I needed some shorter linear bearing when I rebuilt by One-Up printer. The extruder carriage is only half as wide as the stock one. These fit the bill. The only difference between this and the stock bearings is that they are half the length.