Filament Pelletizer

thingiverse

What do I do with scraps of filament and short pieces off the end of the roll? Well, if you have a filament extruder, you can chop them up and toss them into your next extruded batch of filament. I was inspired by the Simple Pelletizer by Sungod3k, but it wore out after a few runs because it's all plastic. So I made a more robust version using parts from my junk boxes that are easily reproduceable. The basic components are simple: Johnson RS-775 Motor, 8x22x7 bearings (608ZZ skateboard bearings), 8mm Drill Bit as the cutter, and various screws to hold everything together. You'll also need two screws to fasten the coupler housing to the front of the motor. I used M4x8mm screws that fit the Johnson motor. A nozzle throat is necessary; I used an old one from my printer spare parts, but a 3mm throat would work too as long as the bottom edge is flat. A speed controller is recommended for the motor to adjust the cutter's speed and feed speed. This allows you to vary the length of the pellets produced. Faster on the feed and slower on the cutter produces longer pellets, while slower feed and faster cutter makes shorter pellets. Assembly is straightforward: attach the Motor Coupler Housing to the front of the motor with two screws, then slide in the shaft coupler and drill bit. Tighten the set screws on the coupler through the side slots. Install the bearing into the bearing support and attach it to the front of the coupler housing with four M3x10mm screws. For the Exit Chute, most of the length of the bit can clear off and drop bits into it. I tried smaller chutes but found that small chips would ride up the bit and wedge in. The front end isn't a clog hazard because of the twist drills flutes pulling anything back from that end. I also built a feeder consisting of a Nema 17 stepper motor, an old plastic spring-loaded filament drive, and a simple 555 timer circuit to generate pulses for an A4988 stepper driver. This setup works perfectly!