Group 5 – ReFilament

Team Members

Clara Summerford, Emilie Pursel, Mauricio Navarro, Victer Qiu, Nathan Berner, and Sungsoo Kim


ReFilament is a filament recycler that converts 3D-printed PLA scrap into a spool of fresh filament. The scrap material gets grounded up and extruded into filament that gets pelletized, re-extruded, and wound up at final filament diameter of 1.75 mm ± 3%. The grinder process involves two separate grinders that convert the scrap into coarse grounds then fine grounds. The fine grounds are then input into a hopper and automatically feed into a custom-machined extruder screw. The expanding core diameter of the extruder screw raises the shearing rate of the filament material, which generates enough viscous heating to melt and extrude the filament at the target PLA extrusion temperature. The filament is then screened by proximity sensors and enters a pair of drive rollers whose speed is controlled using closed-loop feedback. The drive roller speed is adjusted to refine the diameter into tolerance via tension control. A traverse mechanism driven by a 3D-printed self-reversing screw ensures that the filament is evenly distributed as it gets wound on a spool. The pelletizer is a custom 2D-cut cutter gear that uses orthogonal cutting to chop the filament into segments of 3-5 mm in length. ReFilament was designed to produce recycled PLA filament at a rate of over 800 g/hour while meeting a hoop stress factor of safety of 3.5 to prevent catastrophic extruder pipe bursting. The material cost, OTS parts cost, and manufacturing and assembly labor cost for the machine totals $4,700

Pitch Video

3D Interactive Product Model

The following is an interactive 3D model of the product design. You can view and rotate the product assembly in different orientations and views, including an exploded view to see the various parts that make up the assembly.