Prusa i3 "Tweety" Parametric (dual) Compact Extruder

thingiverse

I loved the great design by thinkyhead for a simple geared extruder on a prusa i3. I modded it to fit two extruders (one mirrored) and use a mk8 (rather than mk7) drive gear. To make this work, I made a few notable modifications: I moved the motor over 2mm to make the hobbed gear contact the filament I made the mount holes 30mm apart so it would fit a standard dual carriage that has 30-20-30 spacing. I made the mount holes movable up and down to let you easily tweak the height of the extruder heads and level them I got rid of the extra mounting bolt hole so you don't have to print a special carriage (it's not as stable, but a few zip ties solve this. I removed the cone transition for the entrance of the filament to the hotend from the hobbed gear to reduce the chance of buckling with softer filaments. Finally, I pushed the bore for the j-head mount down slightly because mine fit a little to tight for comfort. I also made mods for the fan mount since I was using a smaller fan. I've included the fan I use and I hate to not reference it's thing#, but I can't remember where I got it. I included the original tweety openscad file for reverence. If you use the 50:1 geared stepper motors from 2engineers.com you'll want to use a heatsink (I found one intended for the PG35L at ultibots.com and you might consider going with that motor and modifying this design for it) I would print everything in ABS since the motor gets pretty warm - I actually deformed the idler when I printed for a while without a heatsink. You'll also need to modify your firmware according to 2engineers.com to prevent damage from acceleration (in addition to enabling dual extrusion). enjoy