Creality CR-6 BMG direct drive mount directly on the strain gauge

thingiverse

There are several direct drive mounts for CR10, Orbiter and BMG style extruders available on Thingiverse for the Creality CR-6 SE and CR-6 MAX. These however inherently suffer from interference with the strain gauge when they are mounted to the X-carriage. There are a few examples of other extruder mounts that dont suffer from this like the one from Sebazzz to mount the Biqu H2: https://www.thingiverse.com/thing:4729803. As Sebazzz did for the BIQU H2 I designed one for the BMG extruder.I could have gone 2 ways: use the full BMG extruder and design a mount where it clips on. That did not work out as it was too weak and quickly became wobbly. So I integrated the whole extruder in one printed part in the mount resulting in a sturdy system. That made it necessary to remodel the grabcad model as it was made for injection molding. Adding the necessary tolerances for 3D printing resulted in a working extruder. I salvaged the internals of my BMG clone and installed them in the printed shell. To complete the setup I remixed https://www.thingiverse.com/thing:4657122 to properly mount and fix the cables. The stepper used is a standard 23mm Nema 17 motor. For the one I got I didn't need to invert the rotation as the cable already had inverted wires. The BMG extruder itself weighs 51 g whic is slightly less than the clone I stripped the internals from. The complete system: hot end, fan, extruder and motor weighs 231 g. V1.1 has a few minor changes: (1)On the motor mount an extra cutout is made te ease mounting the large gear (2)The gear has been moved up 0.2 mm to improve compatibility with cheap gears (I had one that very cheap set started to skip). The 0.2 mm move is mirrored in the extruder cover. (3)The seat of the PTFE tube has been made flat to avoid it slipping up and allowing plastic to end up between the nozzle an the PTFE tube (mounting instruction adapted to this as well) (4)The top of the cable mount has been moved forward to ease access with the Allen key to the extruder. (5)A version with 3mm nut mount for the gear lever has been added. Be aware that a shorter spring might be needed to use this version. In some BMG clone sets the screw is rather short. An adapter to mount the Dragon hot end to this extruder is published here: https://www.thingiverse.com/thing:4837641