3D Printer Slider Sliding Block Linear Bearing SCS8UU Motion Ball 4pcs for Prusa i3 DIY Kit Eewolf

Just what I needed minus the bearings. Please offer these with plastic dryliner bearings

The media could not be loaded.  As seen in the video the black plastic bearing is the way they should work. Not too tight, not too loose but just right. The first bearing I move after the plastic one is very loose and the second is very tight. In the images, you can see that one of the bearings was shipped with no black metal piece to hold the bearing in on one side. Each bearing should have two black little metal pieces to keep the bearing inside. Just so everyone knows, I ran the bearings up and down the metal rod about 30 times or more to wear them in and the video shows how they respond afterward.Update (went from 2 to 3 out of 5 stars on the review because I finally have a working set):I just some replacements... Those had issues as well. This time all of them seem to have good bearings and have all the clamps to hold them in the housing. However, some of the new ones were not even threaded all the way through so the screws I had would not work on some of the new ones. It seems getting a WORKING set of these is a big shot in the dark. It's unfortunate though, the ones that are made right work well from what I can tell. My advice, if you need 4 order two packs of four and send back the defective ones. That's what I had to do but it took me over a week to get everything straighten out.

I've used these sliding blocks on my 3D printer and after repeated use I've noticed some of the C rings or retaining rings, however you call them that hold in the bearing, protrude out enough that they scratch the rods they slide on. I can't say for sure that I have them properly aligned, but I would still think the designer should have considered the damage these could cause at slightly off angles.

I did not like that the barrings were louder the the original ones

Initially the pillow blocks looked to be fine, although I had wished they were threaded all the way.As I started to try and use these threaded holes are not machine straight. I had one screw hole that was machined about 10 degrees off. I could deal with crappy bearings if the pillow blocks were ok to good. But these are junk.Thepillow blocks are bad the bearings in them are bad. Only one bearing was in good shape. One has bearings that barely move and the other two the bearing do not seem seem to be touching the smooth rod at all.I had initially gave them only three stars because I thought the Pillow Blocks were ok, but they are not so I am down grading the review to one star.

Linear bearings are supposed to be a precision part. When in use the sliding action should be smooth. These bearings look decent but when in use they bind, jerk and are horrible. How anyone can put a two star rating or more is beyond my understanding. Total waste of time.