Reinforced 3 bolt Y axis motor mount for Prusa i3 mk3

thingiverse

Update 7/19/18 - I'm thrilled to finally update this post after multiple members requested that I include end stops in this motor mount, and that's exactly what I've done in the new update (rev 3 file). Along with adding end stops, I also included a slot for tightening up the set screw on the pulley. For anyone who prefers the original rev 2 file, it's still available. Update 3/10/18 - I recently checked the motor mount in a 3D model of the Prusa i3 mk3 with R2 components by jzkmath and was pleased to see that it still works beautifully, correcting any misalignment inherent in the stock mount. I've noticed many comments from people asking if a third screw can be added to the motor mount, so I decided to revisit the model and investigate. After adjusting some bolt lengths and tweaking features on the original motor mount, I was able to easily add this feature. Initially, I didn't want to reprint the motor mount due to the .5mm offset that's standard on the printer, but since I needed to make the mount more rigid and add the third bolt, I figured it was a good opportunity to correct this misalignment in the process. This mount is designed to be used with the stock belt holder only. With this mount, there's no longer any type of misalignment. I also added 1.5mm to the face of the mount so that the motor is moved to the side, placing the motor shaft in the proper location for the pulley to be centered on the shaft. This gives an even amount of side-to-side adjustment of the pulley's location, eliminating issues with belt rubbing due to a lack of pulley adjustment. This pairs nicely with my adjustable belt tensioner (https://www.thingiverse.com/thing:2786671) and, along with the stock belt holder, provides perfect belt parallelism as well as no belt misalignment. Unfortunately, adding the third screw requires replacing some hardware from the stock setup. You'll need two M3 x 30mm socket head cap screws and one M3 x 16mm (longer won't hurt) socket head cap screw. All other hardware remains the same; see the assembly drawing for screw locations. I'd like to extend a big thank you to jweaver for testing as well as providing pictures!