LM8UU Bearing Holder Using Single Cable Tie

thingiverse

I built these so that my Tronxy P802E could use plastic bushings on its bed instead of loud ball bearings. Plastic bushings can bind if they are slightly misaligned, causing motor skips and making it a tedious process to get them aligned properly. These holders keep the bushing in place using a single central cable tie which allows for enough flexibility to avoid binding while holding securely enough that there is no extra wobble to the bed. Switching to printed bushings made things much easier for me. What also made the transition to bushings successful was my switch from an acrylic to an aluminum bed carriage. My printers' y-stop switch touches off on the bearing block, so one design has a wall on one end. This gives them a more stable base for printing on edge which provides a smoother saddle for the bushing. I highly recommend replacing your noisy bearings with Igus or printed bearings like Igus. My prints are now extremely smooth! Even when my original bearings were in good condition, it wasn't this nice. I used the printed bearings from https://www.thingiverse.com/thing:1811769 because they have a variety of inner diameters so you can get that perfect fit. I am currently using PLA on my bed and nylon on my x carriage to see how they hold up. Note: These bushings required a bit more force to move than bearings even when well aligned, so I had to adjust my stepper up a bit to avoid skipped steps. Do not lubricate with any oil or grease! I found that lubrication will increase static friction and increase skipping risk. It makes them slide easier once moving, but it will be stickier when starting. - UPDATE Jan 19 2018 I have tried several different materials for printed bushings now for a while and here are my thoughts: - NYLON (Taulmen Bridge) - This has too much "stiction" (static friction). It slides smooth once moving, but is grippy when getting started. This is probably due to its rubbery nature. My motors couldn't provide enough torque to avoid skips. - PLA - This is the easiest gliding filament. Works really well. Only downside is that you don't want to run in a warm environment. I found that even 40C ambient can result in very slight deformations over time (especially if the bed is really hot). And this will eventually cause skips. 35C ambient seems to be very safe though. - PETG - Have been using for a while on my x axis only and it works good so far. Doesn't slide quite as easily as PLA but not that much worse. No obvious stiction. My hope is that it will handle higher ambient temperatures better than PLA, but have not had it above 35C yet as I still have PLA on my bed bushings. Again, I am not lubricating these bushings. All wet lubes dramatically increase stiction. I did try a dry Teflon spray and that did seem to help slightly, but the effect seemed very temporary and would require reapplication every handful of hours of printing. UPDATE May 25 2018 See https://www.thingiverse.com/thing:2929741 for bushings specifically designed for this application. Pla bushings were starting to bind slightly due to slowly deforming under the combination of a heated enclosure and a lot of 110c bed temperature time. So I replaced with petg bushings.