Bunny and Bear Geared MK3 Extruder

thingiverse

Note: This project has been surpassed by our advanced "Short Ears" extruders, which feature a shorter moment arm, separately printable hot fins, Mosquito capability, and improved filament sensor systems on the MK3S. For MK3 https://www.thingiverse.com/thing:3606189 For MK3S https://www.thingiverse.com/thing:3621115 Bunny and Bear Retrograde Extruder: This design features a unique pulley gearing system inspired by Skelestruder, with project-specific pulleys and spacers. Materials Needed: 1 x 5 mm shaft rod (58.5 mm long for 2 bearings, or 62.5 mm long for 3 bearings) Grind two flats 0.38 to 0.4 mm deep Bunny and Bear Retrograde: Length: 58.5 mm for 2 bearings (Optional 62.5 mm long if 3 bearings) Pulley Flat: 0 to 9 mm Bondtech Flat: 48 mm to end Bunny and Bear Antegrade Extruder: This design features a shorter length and unique pulley gearing system inspired by Skelestruder, with project-specific pulleys and spacers. Materials Needed: 1 x 5 mm shaft rod (44 mm long for 3 bearings) Grind two flats 0.38 to 0.4 mm deep Bunny and Bear Antegrade: Length: 44 mm (3 bearings) Pulley Flat: 0 to 15 mm Bondtech Flat: 26 mm to end Components: * 1 x continuous loop 140-2GT-6 Timing Belt * 1 x M3 square nut * 1 x M3 set screw * M3 hex nuts & bolts (various lengths from 12 to 30 mm long) * M3 washers * 1 x 16T drive pulley (use one for a 10 mm wide GT2 belt despite the belt being 6 mm wide) Motor: 1.8 degree, STEPPERONLINE Nema 17 Bipolar Stepper Motor 0.7A 13Ncm (18.4oz.in) 17HS10-0704S Wiring Harness for Motor: You MUST also set e-steps by sending g-codes to printer M92 E980 M500 Retrograde Geared Option: https://youtu.be/RBTR8ucOMfA Standard Geared Option: https://youtu.be/4aEE6gMUx9s Pulley gearing inspired by Skelestruder. Project has moved on to its own pulley and spacers. Updates: B04 - Interlocking stubs align motor gear plate to extruder body. B05 - Increased pulley / wall clearance at bottom of gearbox. Strengthened motor mount. B06 - Removed split motor plate gearbox variant. In my judgement, it excessive flexes. Also, I have removed support material enough times from inside the motor plate gearbox that I am you can do it. B06 - Fixed regression blocking idler door clearance. B07 - Fixed motor body interference with front gear plate Fixed incorrect M3 nut hole sizes on gear plate Now recommending 3 bearings instead of just two in front. Easier support material removal with mod settings in 3mf file. Added some build process photos. B08 - Inset motor mounting bolts to help clear bolt heads of x-axis mounts. Added accessory motor plate adapter for use of motors directly (without gearing) while modified extruder is installed. B09 - Added retrograde motor plate option. B10 - Minor motor fitment adjustment of retrograde motor plate Added Bunny Science pulley and spacers. Fixed bunny blocking set screw access. Reorganized 3mf file contents to make each more complete Loosened fit of shaft spacers. Added shaft cutting guides Updated BNB Universal x-carriage to be ready for Short Ears MK3S edition. Intended to avoid future reprinting and re-installation of x-carriage.