Filament mixer / dual extrusion / mixing extruder

thingiverse

Updated 11/9/2016 - added versions for M5 and BSP1/8 threaded PTFE coupler, and a holder to prevent the mixer from tilting. Designed to convert any single bowden hotend setup into a dual extruder setup, simply add a second extruder. If using this setup, you won't need to calibrate nozzle offsets as it uses one nozzle for both filaments. To manage filament changes, use some gcode; otherwise, assembling is straightforward: print two copies of the body and assemble with three M5 bowden PTFE couplers. The idea is that when changing filaments, back out the filament into the filament mixer, then push in the second filament, purge, and continue. Note: this setup is designed for 1.75mm filament. GCode used in the tool change script in Simplify3D as follows: T[old_tool] G92 E0 G1 E-30.000 F3600 ; fast initial retract G1 E-50.000 F300 ; slow down the retract to let the filament cool and reduce strings G1 E-120.000 F3600 ; back out the remaining distance to clear the mixer, tuning this length for your setup is recommended G1 X150 Y0 F7200 ; go to purge position to prevent squirting filament everywhere T[new_tool] ; purge new tool G92 E0 G1 E120.000 F900 ; push the new filament into the hotend G1 E130.000 F450 ; slow down the push as it enters the heater block G1 E150.000 F200 ; purge the nozzle, probably more than required G1 E148.000 F1800 ; small retract to encourage the purge to snap off G92 E0