Mini dual Y adapter for E3D V6 style hotend with bowden extruders

thingiverse

Inspired by the Dagnall Y Extruder, a custom pneumatic coupling is created. The coupling stands approximately 4cm tall and directly mounts onto an alu heat sink. A bottom pneumatic coupling has been drilled through to save space. The top part was sawed off. Ridges were added to the hex nut section for better grip on the plastic. It was then heated and press-fitted into place. One millimeter holes are drilled for superglue to secure PTFE tubing and the bottom coupling. A needle is used to help penetrate the glue. To ensure a tight fit, it's recommended that a 4mm drill be used to widen the hole in the alu heat sink and get the PTFE tube down to the heat break barrel. The tube should then be cut to length for a secure fit when screwed into place. A minimum of 8cm retraction is needed for filament switching, but using 10+ will make it easier to avoid headaches. The pneumatic coupling seems very robust and has survived many filament crashes caused by bad gcode or slicing. It's also survived several hard crashes where an angry gorilla was trying to force the filament through when the extruder started grinding plastic - a situation that arises from dual extrusion without a mixing head. Some gcode snippets and hacks have worked for me (11cm retraction, direct drive extruder). The code assumes the second extruder filament is down in the hotend, and the first filament halfway down the pneumatic coupling or at the end of its bowden tube. Startup: T1; Select the second tool, expecting it to be down in the hotend G92 E0; Reset the extruder G1 E-110 F4200; Retract T1 to park position T0; Select the first tool, expecting it to be roughly in the park position and push down into heat block G92 E0; Reset the extruder G1 E90 F3000; Advance T0 G92 E0; Reset the extruder G1 E20 F400; Advance T0 slowly and hope it extrudes some filament... G92 E0; Reset the extruder Slic3r custom tool change gcode: T[previous_extruder] G92 E0 G1 E-110 F4200 G92 E0 T[next_extruder] G92 E0 G1 E110 F4200 G92 E0