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.

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.

Making Tips

The dimensions in the model are optimised for printing at 0.2mm layer height. Printing at other layer heights such as 0.24 or 0.15 would cause Z dimension inaccuracy.
Print the 48 teeth pulley at 0.1mm height with extremely slow outer wall speed (under 10mm/s). Use glossy material instead of matte.
Retract at all times while printing the frames. Otherwise the filament will ooze during travel and cause under extrusion at perimeters.
No support needed for the three frames and bearing holder.
Print top and base plate of frame at 100% infill. The compression spring apply massive force to the left side of top plate. Make sure it's rigid.
Rub the cylinder pin on hard surface such as concrete or stone to turn it into a D shaft
If printing with high temperature filament such as ABS or PC, scale the model larger in X and Y direction in slicer to compensate for shrinkage. For reference, my experience with UP ABS works with 100.3% scale.
For Ultimaker 2, add a piece of 1mm silicon sheet between the motor and frame as damper. This will reduce the retraction noise of motor vibrating frame
Bill of Materials

Belts & Pulleys
1 x GT2 6mm Socket Pulley 48 Teeth (printed)
1 x GT2 6mm/10mm Pulley 5mm Bore 16 Teeth
3 x GT2 6mm Pulley 5mm Bore 20 Teeth - 16x16mm, M4 set screw
2 x GT2 6mm Belt 65 teeth - 130mm

Bolts & Nuts
2 x M3x16 Flanged Button Head Allen Bolt
5 x M3x12 Flanged Button Head Allen Bolt
4 x M3x30 (Flanged) Button Head Allen Bolt
1 x M3x20 (Flanged) Button Head Allen Bolt
2 x M3x12 Countersunk Socket Allen Bolt
6 X M3 Standard Hex Nut
2 x M4x10 Button Head Allen Bolt
2 x M4x10 Grub Screw Socket Set Flat Point - DIN 916
2 x M4 Standard Hex Nut
1 x M6x16 Countersunk Socket Allen Bolt - DIN 7991
1 x M6 Square Nut - DIN 562

Others
2 x Gear Drive - stright teeth gear for 1.75, Ultimaker gear for 2.85/3.0
2 x Cylinder Pin 5x45
1 x Cylinder Pin 5x30
6 x Bearing 605ZZ 5x14x5
2 x Bearing 624ZZ 4x13x5
1 x Ultimaker 2 Bed Compression Spring 7x9.4x1.2 16mm
1 x 1mm thick Silicone sheet - larger than 42x42mm (optional)
1 x 1.8° NEMA17 Stepper Motor - D Shaft of 5x24mm (optional)
1 x PTFE Bowden Fitting - PC4/PC6 with G1/8 or R1/8 thread for 1.75/3.00, Ultimaker Bowden Coupling for 2.85