- B2D stands for "Belted Dual Drive". It's a bowden style extruder that has extra grip to filament and is hardly audible during retraction. FEATURES: - Dual drive gear for improved grip, and prevent grinding filament. Frequent retraction is more reliable - Belt driven motion hardly 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 - 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 more torque for super fast extrusion rate. - Operation video recording at: https://www.youtube.com/watch?v=JjQ7FrQe8s4 - Drive force test with E3D Hobb-Goblin gears, max of 9-10kg (max spring compression. NEMA17 48mm long with 0.55N.m torque, rated current of 1.5A running at 1.25A) at: https://www.youtube.com/watch?v=QorkxMkFOio UPDATE: - 26/05/2017 - v2 update. Slightly reduced tension of the belt. Raised the parts that could interfere with set crews which sticks out from the drive gear. - 23/08/2017 - New stronger base plate. - 20/09/2017 - Fixed the Bowden connector for 2.85 being too tight. Adjustable tension for the v3 base plates.