Updated: Coupler V3 improved tolerances around bowden tube retainer and screw hole.

The Coupler and Guide are a set of complementary accessories that will help you run a short length of PTFE tube from inside the filament compartment through to the exterior, allowing you to print 3rd party filaments on larger spools without having to leave the compartment door open.

Note: If you'd like to add an external spool holder, I'd recommend doing that first before drilling a hole in your Adventurer 3! Check out my Low Friction Spool Holder.

Optional: Print out and use the guide to help drill a hole in the filament compartment door. I positioned the guide on the door exterior leaving space for an external spool holder. You can secure the guide firmly and temporarily with a thick bead of hot glue around it's perimeter. Use the guide with a 4mm drill bit to drill out a hole.

Print out the coupler and insert a PTFE tube into it. Verify the tube is not deformed in any way i.e. the hole through which the filament passes should look perfectly circular. See the post-processing notes below for more info.

For a good fit I recommend feeding an additional 1-2mm of tube through the coupler before mounting it to the extruder motor housing. I also recommend feeding a length of filament into the PTFE tube through to the extruder motor housing to help you align the coupler. Undo a nearby screw (see picture) and use it to secure the coupler.

Although I did not find it necessary you might run a small bead of hot glue along the neck of the coupler to provide extra rigidity.