B2D Extruder - Strong and Silent Bowden Extruder

- B2D stands for "Belted Dual Drive". It's a bowden style extruder that has extra grip to filament and is hardly audible during retraction. - Preview the 3D model on Sketchfab: https://sketchfab.com/models/8568dba4796e4a238a1051e965c39b2c FEATURES: - Dual drive gear for improved grip, and prevent grinding filament. Frequent retraction is more reliable - Belt driven motion don't generate any noise itself during retraction. The only noise left from extruder would come from the stepper motor vibrating the frame of printer - 3:1 gear ratio to increase torque - Very durable. No wear on belt and pulley over time comparing to printed gears - Adjustable compression of a strong spring - Modular parts for different combination of drive gear, filament and bowden tube - The bowden connector can slide for 3.5mm. Any diameter of drive gear between 7-12mm is applicable - Quick changeable drive gears. Can use large gear with slower motor speed for silent operation, and small gears with mo