Traditional bushing 8x15x24mm (LM8UU) with grease trap

thingiverse

Traditional 8mm bushings feature an internal grease trap. Do not use MoS2 grease for printed bushings; it fails miserably. PTFE spray can oil works with PETG bushings if wiped dry after saturation. I have not tested silicon-based or lithium-based lubricants. Initially, I searched for graphite dry lubricant spray as a first choice but couldn't find any locally, so I chose PTFE spray can oil instead and it seems to work when wiped dry after saturation. My initial attempt at greasing the Y-axis involved using MoS2 dark grey grease, which worked sufficiently for linear ball bearings. However, when I used MoS2 dark grey grease on my printed bushings, it didn't work at all; I tried it with PLA and PETG bushings, but they both got stuck to the rods after one day or less due to resistance from the stepper motor. I then created a new batch of PETG bushings and tested them with PTFE spray oil (tens of thousands of PTFE balls per mm2). I ground the bushings to tolerance using a threaded rod while slowly rotating and moving both pieces along the rod, applying pressure. The process involves checking the bushing against the bearing rod after each grind until satisfied with the tolerance. I found that the bushings should slide easily along the rods when dry but stick to the rod when saturated with PTFE spray can oil. I ground the bushings until they just slid easily by gravity on the rods but stuck to the rod when wet. Once satisfied, I saturated both the rods and bushings with PTFE spray can oil and then thoroughly wiped them all dry with toilet paper. When saturated, the bushings do not fall by gravity on the rods; instead, they are sucked into place by viscosity. However, after wiping them clean, they slide easily and quickly along the rods!