Although distributed additive manufacturing can provide high returns on investment, the current markup on commercial filament over base polymers limits deployment. These cost barriers can be surmounted by eliminating the entire process of fusing filament by three-dimensional (3-D) printing products directly from polymer granules. Fused granular fabrication (FGF) (or fused particle fabrication (FPF)) is being held back in part by the accessibility of low-cost pelletizers and choppers. An open-source 3-D printable invention disclosed here allows for precisely controlled pelletizing of both single thermopolymers as well as composites for 3-D printing. The system is designed, built, and tested for its ability to provide high-tolerance thermopolymer pellets with a number of sizes capable of being used in an FGF printer. In addition, the chopping pelletizer is tested for its ability to chop multi-materials simultaneously for color mixing and composite fabrication as well as precise fractional measuring back to filament. The US$185 open-source 3-D printable pelletizer chopper system was successfully fabricated and has a 0.5 kg/h throughput with one motor, and 1.0 kg/h throughput with two motors using only 0.24 kWh/kg during the chopping process. Pellets were successfully printed directly via FGF as well as indirectly after being converted into high-tolerance filament in a recyclebot.
