Pack of 4pcs 12 mm SC12UU SCS12UU Linear Ball Bearing Slider Slide Bushing Replacement CNC

So, these work, and they are cheap, but just be aware that there is a lot of room for user error on a product like this. The tolerances on getting a sliding linear rail going through two of these are incredibly tight. A quarter of a turn too much on one screw and the system will lock up. You also really want to add some grease or lubricant to these and your shaft. They make a decent amount of noise when the shaft gets moving through them. Taking off a star because I had one bearing that two of the threads were wrong/mis-threaded on.

If all 4 worked as good a 1 of them does then this would be a 4-star purchase. As other have mentioned, not all of the mounting holes were milled properly - it is not that they were not tapped correctly, but rather some of the holes were milled to wide part of the way. Screws still secure them, but the couple of bad holes have less than half the threads. This alone should have been my signal to not buy them.3 of the 4 are junk. They are not smooth when not under a load, can be made to feel better if you press them towards the rod (force aligns the inner bearings), and will bind if you have a fast servo coupled with an equipment plate that is not supported equally across all the bearings.

I used these in a 3-axis arduino CNC build. The most important center-line position and tolerance is accurate with the specs, however, there was no tolerances on any of the less critical dimensions. Following the 5mm bolt hole spacing in the spec sheet, I had no problem bolting these to the plates I machined for them. What I found is that most of the other dimensions of the product are +/- 1mm or perhaps more, so be sure to allow plenty of clarance. Check alignment of critical assembly with an indicator.

decent price, but 3/4 good, that last one is.... questionableI do suggest flushing them out with a cleaner just to get all of the manufacturing coating / etc out of it. and lube it again, and run it through some long runs to break it in.

Bought these to replace the low quality bearings that came with my Anet A8 3D printer. Unfortunately these were not any better than the ones I had. Sent them back.

Thanks guys. It appreciate your job.

Great guides, smooth and built well. No issue supporting my 10lb jig table on my home made wood cnc. Easy to mount using 5mm screws.

Bearings fall out