Reverse Bowden for Prusa i3

thingiverse

Here's a reverse-Bowden setup for the Prusa I3 MK2 and MK3. It's called "reverse-Bowden" because the extruder doesn't push filament through a PTFE tube into the hot-end. Instead, it pulls the filament through the tube. There are a few advantages (real or imagined) to using a reverse-Bowden setup for the Prusa i3. It allows you to take the heavy filament spool off the frame. It eliminates the need for a filament guide. Also, travel movements of the print head don't cause the filament to un-spool (a real problem with PETG.) In my design, retraction is not affected. The PTFE tube sits, unattached, on top of the extruder and lifts up on retractions instead of having to push the filament back up the tube. (May not be a real problem, but it's one less thing to worry about.) Note that I have, once again, taken Area51's clip design (see http://www.thingiverse.com/thing:1940105) and used it in my own design. I have reverse-engineered it into OpenSCAD to make it easier to fit projects of mine that mount on the Prusa's frame. but the original design is his. This clip-mount makes for easy-on, easy-off and won't break off the ends when you attach or remove it (like I've done with the original Prusa spool holder "clip".) If you're interested, you can find the design for the spool holder (pictured) here: https://www.thingiverse.com/thing:2618257 It works surprisingly well for the two sides not being connected. I just drop a spool on it, wiggle the spool and the two sides line right up.