(Robo3D) E3D hotend direct drive (geared/non geared) extruder

Direct drive upgrade for the Robo3D or any printer, using a E3D hotend and a MK8 drivegear using a Nema17 stepper motor with or without planetary gearbox. The extruder could be mounted on the standard Robo3D X-carriage, this was the main reason why I created another direct drive extruder. A change in the firmware is required to adapt the new steps per mm value.

Two variants are possible, usage of the standard Nema17 motor or a geared Nema17 with gear ratio ~ 5:1 (http://www.omc-stepperonline.com/gear-ratio-51-planetary-gearbox-with-nema-17-stepper-motor-17hs130404spg5-p-140.html). The geared version offers more torque and a better step resolution, current must be limited to not overheat the motor.

Good performance at printing of flexible filament, the printing speed needs to be reduced, but this is normal for the flexible materials.

Advantages over the stock extruder:

• Less filament jams (at my printer)
• Compact setup
• Less noise
• More constant flowrate (again, at my printer)
• Low cost due to reuse of some stock components

Disadvantages:

• Surface a little bit more rough due to less steps per mm from the stepper

Additional parts:
1 x E3D hotend
1 x MK8 drivegear (7mm effective diameter)
1 x 694 bearing (4x11x4mm)
1 x 30 x 7 mm spring quite strong
1 x M3 x 6 screw (for non geared stepper)
4 x M3 x 10 flathead screw (for geared stepper)
6 x M3 x 12 screws
1 x M3 x 20 screw
2 x M3 x 20 screws (for non geared stepper)
2 x M3 x 30 screws
6 x M3 washers
2 x M3 nuts
1 x M3 nut (for geared stepper)
1 x M4 x 10 screw
1 x 30 x 30 mm fan
(1 x 40 x 40 mm stock fan)
(2 x M4 stock extruder mount screws)
(1 x Nema 17 stock stepper motor)