Direct Drive extruder for mk8 and 3/8" pneumatic connector

thingiverse

I need an extruder that fits the S-BOX's holes for NEMA 17 so I can mount two of them. I only have couplers in 3/8" to 4mm, so none of the ones I saw would work for me. I took ideas from various people on this site and drew it in Sketchup. The result is working beautifully! I put some PTFE tubes on there to help with 1.75mm filament flow, but I figure you could get away without them if you use 3mm (haven't tried that). My MK polea has a 7mm diameter hobbed bearing. To print the second part, I mirrored it in my slicer. To "tap" the quick disconnect, I heated it up with a blowtorch for a sec. I added the extruder_idler file as a replacement for P2 - all I changed were some heights since the other one was hanging way out over the filament and would occasionally jam. Here is Version 2. After almost 7-8 months of use, two idlers broke under the ruleman's force so I redesigned it using a smaller ruleman (624z) to keep an M4 as the axle instead of the huge M8 that wouldn't even fit in that space! So far all my test runs with the new design went much better than the original. You can find the new STL files and sources online for your convenience. Simple direct drive extruder, mounts on nema17 spacing holes. Version 2 is more durable. Version 3 has a motor spacer which allows the part that guides the filament to be printed closer to the mk8 bearing. It's really simple and I've been using this design (with modifications) for ages now with no issues. If you use the hydraulic connectors that won't let your ptfe tube pass all the way in, I recommend adding some material at the end so you can leave them on without cutting pieces off, worked great even on flexible!