Bunny Science Gear Shaft Cutting Guides

thingiverse

Human: Shaft cutting and flat grinding guides for the Bunny Science geared extruder projects are now consolidated here, making it easier to keep them all up to date in various projects. Links to these guides can be found in each extruder or gearbox project. 3mf files are included to preset Slic3r for best accuracy, ensuring precise results. The guides are named with three numbers indicating the length in mm, total length of shaft / end of pulley flat / start of Bondtech flat. Slide a rod into the end of the guide to see where and approximately how deep to grind flats. The length of the guide is the final length of the shaft. It's now recommended to grind flats all the way to the ends of the shaft to simplify alignment during assembly. The guides are dimensioned to fit snugly with 5 mm rod when printed in PETG at 0.10 mm layer thickness, 0.20 mm bottom layer thickness, 25% gyroid fill, 5 top layers, and 5 bottom layers. Grind the flat to an approximate depth and extent of guide depressions. The depressions for flats should print out as just under 0.4 mm depth with these settings, but may vary depending on your printer and filament. *** Removing and reinserting the rod during grinding may rotate its position and reduce accuracy. To achieve best accuracy, calibrate from base of guide to top of rod before any grinding. Take that measurement and subtract 0.38 mm to obtain your target Bondtech flat measurement. This lets you measure progress without taking the rod out of the guide. Best practice is to check the critical Bondtech flat depth with a caliper during grinding. Grind the Bondtech flat incrementally and verify with a caliper that the depth is 0.38 to 0.4 mm for proper Bondtech set screw engagement. Too shallow, and the set screw will grind against plastic or other drive gear. Too deep, and the set screw will not tighten against the shaft flat. It's recommended to grind flats before cutting the shaft to length. Grinding of flats with a Dremel cutoff wheel won't melt the guide, but cutting through the entire diameter of the rod will. Remove the guide after making an initial nick for cutoff. The Bunny and Bear retrograde shaft is intentionally shorter than the BNBTR retrograde shaft. The Bunny and Bear retrograde extruder places the motor about 3 mm closer to x-axis rods than possible with BNBTR. --- Change History Added 20 mm wide versions Fixed naming issue in Bunny Science MK3S Retro Upgrade guides Removed 10 mm wide versions Tightened rod grid Improved rod inset to be more flush with the top of the guide Thickened guide base by 1 mm Changed recommended print settings Added a guide for the Bunny and Bear "Short Ears" (SE) extruder Increased length of Short Ears shaft by 2 mm to make flat easier to see beyond Bondtech.