Our Process

Shredder Design

Before we could start designing a shredder, we had to determine how best to shred the plastic. We first tried shredding it by hand, but it was much too inefficient. We then tried various other methods of shredding, including a paper shredder, a blender, and a food processor. We discovered that the paper shredder gave us the most evenly-sized pieces, but they weren't small enough to work well in the extruder. The paper shredder also jammed a lot if we didn't load the plastic in just right, and the bottles had to be cut into strips before we could feed them in. The blender and food processor worked alright for plastic near the bottom, but the pieces weren't very uniform, and anything near the top of the blender didn't get cut at all. 
From these results, we determined that the best idea for a shredder would be similar to a paper shredder, but heavier-duty, could make smaller pieces, and could load whole bottles into it.

Extruder Design

The extruder will take the shredded plastic bottles and melt them into a filament for our printer to use. The plastics shreds will be poured into the tube through the ovular hole on the top. The ovular shape prevents plastic bits from getting stuck in corners, and so makes the process cleaner. Then, the corkscrew carries the plastic shreds through the metal tube, where they will be melted. Finally, the melted plastic will be extruded through a nozzle at the end of the tube, where it will come out at a very specific size that works in our 3D printer.