Review on 🔧 Enhanced Solid Polymer LM12UU Bearing Shaft for Superior Performance by Jared Winebrenner

I used this for the Z axis of my CoreXY 3D printer (custom made). I made sure the linear rods were perfectly parallel. These bearings move normally until I set up the print bed with heater, glass plate, etc. When under cantilever load, it will not slide smoothly. Knit like crazy. I understand they are supposed to be "self-lubricating", meaning they slide without oil or grease. But not in my case. I took them off and installed them a couple of times, making sure the bars were parallel etc, disappointed. If anyone is looking at these for the Z axis I would recommend long one piece linear bearings (LM12LUU) with a flange like those used in Creality Ender or Sainsmart printers.