Direct (non-bowden) extruder for Ultimaker

youmagine

Removing the bowden tube and attaching the extruder directly to the head is not just a fun project, but a necessary one to make printing of flexible filaments possible. Filaflex and Ninjaflex are great examples, but this modification can be applied to any filament that struggles with long bowdens. The final print results are astonishing - no underextrusion whatsoever and perfect layer adhesion. Printing at 25mm/min yields good results, but going faster than that makes the heavy head a bit shaky and degrades print quality. For my setup, I have to increase flow in Cura or on the machine to 140% due to the smaller diameter at the teeth of my hobbed screw. You can see it in action: this modification is derived from the famous "Greg's-Wade's-Taylor's-Someone's extruder" and uses the original stepper from the Ultimaker. The whole thing is mounted on top of the moving head, making it easy to swap between direct and original extrusion without having to disconnect the sensor or heater. I still haven't found a place to mount the small ADC board, so I leave it hanging from its wires for now. All you need is a hobbed bar or bolt - I use the excellent Hyena from Arcol.hu, but any 8mm hobbed/knurled bolt with threads on both sides will do just fine. You'll also need three 608 bearings (skateboards/inlines), a small piece of bowden tube (I used a 4x6 aluminum tube, about 70mm long so it doesn't need to be flexible), and some assorted M3 and M4 bolts plus two springs. The rest is printed. To reverse the running direction of the motor, simply swap the cables in each pair or use a custom crossover XLR cable like I do - this way you can disconnect the motor using XLR connectors without needing an extra cable. With the extra cable, the motor will run in the opposite direction, providing the necessary length. I provide the main body with integrated print support to save filament and printing time. Feel free to improve, comment, and share your own experiences! I include the source files (Solidworks 2012) for those who want to make modifications or improvements. Some STL files are not correctly oriented yet, so take an extra look before printing. This modification is easy to install and fully reversible - no changes are made to the original parts. It takes about 15-20 minutes to swap between direct and original extrusion.