Simple Bowden Herringbone Geared Extruder

thingiverse

Edit: April 1st, 2019: I've added V3, which provides better access to two of the stepper motor bolts that were blocked by the large gear in V2. This change alters the ratio to 2.7:1 instead of 4.25:1, depending on how much extra torque you need. Edit: March 29th, 2019: I've added V2, which features an 8mm clearance between the stepper and the extruder. However, this does make it challenging to access two of the stepper bolts due to different sized gears. This is a work in progress, so I'll update later with V3 when I have time. I also recommend placing a washer between the large gear and bearing to ensure the gear doesn't touch the bearing's outer shell. I'll try to add more pictures later as well. I was searching for a simple geared extruder that utilized existing parts. The design only requires 5 printed components, all of which were completed in under 5 hours. The components are designed to mount either direction, accommodating left or right extruders. I have two installed on my aluminum extrusion frame, mounted in opposite directions. They're currently held in place with one bolt and haven't experienced any issues. Adding a right-angle bracket is straightforward if desired. This extruder uses a standard extruder that mounts to a stepper motor and adds gears. I've printed with PLA and ABS materials. I've been using ABS extensively but only recently tested one made with PLA for durability. The extruder has performed well, providing consistent extrusion and significantly increased torque. You'll need the following parts: -Bowden Extruder: I used the affordable Mk8 left and right extruders as depicted. -2 x 508zz bearings -6 x M3 Nuts -6 x M3x8mm allen bolts -1 x M3x10mm allen bolt -2 x M3x25mm allen bolt -1 x M3x20mm allen bolt -1 x M5x45mm allen bolt (edit: changed to 45mm as it's beneficial to have a lock nut due to the high torque applied by this design) I deliberately designed some parts with tight fits, so minor prep work may be necessary for assembly. The gears and bearing bush require running a 5mm drill through them. This ensures precision and accommodates printers that aren't calibrated. On the M5x45 Allen Bolt, I ground down a flat spot on the head for the locking bolt on the large gear to screw against. Also, file a flat spot for the filament drive gear grub screw to secure properly! My Extruders fit perfectly over the 508zz bearing and were simply pressed into place. If any issues arise, a slight sanding may resolve them.