Digital Fabrication Maker News Workshop
The Lily pellet extruder on a SmartAlu printer designed by Smartfriendz
This project appears in Make: Vol. 75. Subscribe today for more great projects delivered right to your mailbox.

(Editor’s Note: Check back soon for more of Samer’s Lily testing updates.)

Converting a 3D printer to print directly from pellets requires tradeoffs: you’ll gain the ability to reuse plastic material in exchange for some performance limitations. Done carefully, these modifications will open the door to closed-loop recycling, economical pellet feedstock ($2–$5/kg), custom material blends, colors, and properties — but they could reduce the usable print volume and require slower print speeds due to the toolhead’s weight. Ten things to consider:

1. Can the carriage handle the weight and dimensions of the pellet extruder and hot end? Consult your vendor(s). We mounted the Lily pellet extruder on a SmartAlu printer designed by Smartfriendz.

2. Obtain a copy of the firmware on your printer — you may need to modify it. A lot of modifications can be stored in your slicer profile, but various offsets may have to be changed in firmware.

3. Your Z-axis endstop may have to move if the pellet extruder has a long hot end (the Lily does).

4. If you use a BLTouch or induction sensor for bed leveling, you might have to redesign a new X-carriage to accommodate these elements.

5. If possible, make the conversion on a secondary printer in case you need your main printer to prototype parts.

6. Decide how you will feed the pellet extruder. If you’re using a gravity feeder, the hopper has to be above the printer. The Lily pushes filament through a PTFE tube using air, so the pellets or shreds can be fed from any level.

7. While V-wheels are great, expect wear to increase with the heavier head. Consider upgrading at least the X-axis to use a linear rail.

8. If your kit comes with a MOSFET, use it. Running the pellet extruder may consume more power than your printer’s original design. Make sure your power supply can support the additional load.

9. Once it’s all installed, you’ll want to experiment with different materials to determine optimal print speeds, jerk settings, and retraction rates.

10. Expect to tune your PID values to suit your extruder. Recycl3D provided me with a baseline set of numbers and I tuned accordingly.

Whatever extruder you choose, seek support from your vendor, as this is a non-trivial endeavor. They’ll have complete details — Recycl3D was in close contact throughout my Lily installation over several weeks. Of course, if you’re using a DIY pellet extruder, the same checklist applies, but otherwise you’re on your own. You can find many #pelletextruder sources on YouTube, Thingiverse, and other sites.

Samer Najia

I build, therefore I am. I am serial builder of things with more projects than time (I am a flight instructor and I am building a full size 2-seater airplane in the garage). In addition to flying, I enjoy model rocketry ( I 3D print some of my designs) and the Martial Arts.

View more articles by Samer Najia