Prusa i3 MK2: V2 holder clips for Y-axis' bearings (LM8UU and igus drylin RJ4JP-01-08)

thingiverse

ATTENTION: Please read the project's update notes at the bottom of this page! I continue to improve the linear system of the Prusa i3 MK2, making it more stable and reliable with each new effort. This time, I've modified the clips for LM8UU ball bearings to make them easier to adjust on ordinary machines like yours. Just like Thing 1837936 (http://www.thingiverse.com/thing:1837936), you can now mount your bearings "pre-aligned" to the Y-carriage using two M3 screws per bearing. A significant advantage of this design is that the bearings are aligned perfectly in the center of the Y-carriages notch, eliminating any risk of misaligning them vertically. Nevertheless, the Y-carriage still has full range of operation because the clips for the side of the carriage with the two bearings are designed to slide into the gap between the frames' corner pieces. However, I'd like to remind you that I haven't tested these clips mounted directly on my machine yet. The reason is that both of my machines use igus RJZM-01-8 bushings and are in heavy use. So, I'm counting on the Thingiverse community to provide feedback on how the clips perform and what improvements can be made. According to nillabean (YouTube Video: VYW1p3T9tKo), the igus drylin RJ4JP-01-08 bearings are excellent, stiff yet affordable linear bearings (not to confuse with the omnipresent RJMP versions). I've tested them myself and received positive feedback from the community. They fit perfectly, making them "officially supported" by these clips! If you're interested in buying igus DryLin RJ4JP-01-08 bearings, please consider purchasing through my affiliate links provided next. No costs for you but it will help me pay my bills. http://amzn.to/2BkMx1h (Amazon Germany) http://amzn.to/2BijLOK (Amazon UK) Thank you! Please also take a look at my other designs, printer parts, and tools. Project Updates: No. 3 Besides the positive feedback that the clips also work with igus drylin RJ4JP-01-08 bearings, I've now tested them myself too. They fit perfectly! Many thanks to igus for sending me the test samples! So this is no longer a "work in progress." No. 2: Version 2 (V2) of the clips is now available online. You'll find the clips as single objects or as a complete set to download and print. Changelog: The clips now hold LM8UU bearings more tightly Bearings are pressed against the Y frame to prevent them from spinning. M3 screw holes are narrower now, providing better grip for their thread. No. 1: I tried different approaches of how to reverse the screw direction as suggested by bret4. The good... 1) I lowered the clearance of both, the bearing hole and the screw holes. This was a good point; they're now much tighter in fit and won't wiggle or get loose anymore. 2) I lowered the surface that faces the Y-carriage frame by 0.2 mm (one layer's height), which again tightens the bearing more by pressing it against the carriage frame. The bad... As shown on the following pictures, reversing the screw direction results in a big problem: The screw-heads crash against the X-Y-metal-frame. My frame is already lower than Prusa Research suggests in its assembly manual because my frame also rests on the table where the printer stands. Every other user who has assembled the frame as suggested by Prusa will obviously have the same trouble. https://dl.dropboxusercontent.com/u/4928832/lm8uuClipsProblems/ZylindricButtonHeadComparison.jpg https://dl.dropboxusercontent.com/u/4928832/lm8uuClipsProblems/ButtonHeadScrew.jpg https://dl.dropboxusercontent.com/u/4928832/lm8uuClipsProblems/ZylindricScrew.jpg https://dl.dropboxusercontent.com/u/4928832/lm8uuClipsProblems/CrashAgainstTheFrame.jpg The ugly... Trying to move the screws more towards the Y-carriage frame to hide the heads inside the clips and prevent them from crashing against the X-Y-frame results in an ugly geometry (with a big hole). This would affect the stability of the clips, and the screw heads would press against the bearings, which could misalign them again. Anyway, I will publish the tighter fitting version later today. The screw-reversal will be held back until I find something that works better.