Smooth rod / shaft collar from a drilled out M8 nut

thingiverse

This audit aims to enhance Prusa Mendel stiffness and reliability, with related improvements available at http://www.thingiverse.com/thing:11017, http://www.thingiverse.com/thing:10994, and http://www.thingiverse.com/thing:15606. A design addressing smooth rod slippage via a drilled and tapped M5 nut for pulley securing exists but can't be found currently. This solution addresses the issue of limited pressure under trapped nuts in some Mendel x-end designs by using 4 printed collars, which can also be useful in various situations. To create these collars, you need a drill press, center punch, 8mm and 2.5mm drills, an M3 tap, M8 nuts, M3x6 bolts, and a metal file. Drill the nut's center, apply 5-20 circular file strokes, and punch the center of two nut sides 120 degrees apart. Then, use a 2.5mm drill to drill the nut's sides and tap those holes with an M3 tap. File metal scrapes, adjust collars on rods, and tighten as needed for optimal performance. Note that an optimal solution would involve 90-degree screw placement between collars, while drilling the center of faces 120 degrees apart is a reasonable compromise.