PET Bottle Extruder

Our aim with the PET bottle extruder+slicer is to repurpose plastic bottle waste into PET filament for 3D printing. Given its abundance (90% of plastic bottles are made of PET) and food safe properties, we believe this to be a valuable resource for the students at Cooper. Our extruder follows the PETamentor model and consists of a motor, nozzle, heater, and various other components that work together to slice PET bottles into long, uniform strips that are then fed into a repurposed 3D printer hot end. The result is a 1.75mm filament that is ready for use in 3D printing.

To achieve this, we have developed a process that starts with the proper preparation of bottles. The bottles must be made of PETG and have their caps removed. They must be washed thoroughly to remove any food waste and have their labels peeled off. Ideally, any adhesive should also be wiped away. The uneven bottom of the bottle should be cut off to create a uniform circle.

If the bottle is misshapen, a heat gun can be used to gently smooth out the surface, but it must have its cap screwed on and no other holes. This process may result in the bottle bursting, so please be careful when doing this.
The next step involves the slicing process, which employs a slicer made of two ball bearings placed diagonally with edges that are sanded down until they are sharp. This configuration is designed to slice a sheet of material into thin strips, and by mounting a bottle at an angle, a continuous strip can be achieved.

The final step is the extrusion process. The PET strip is cut diagonally and fed into the hot end when it reaches the required temperature. By pulling out the extruded material using pliers, a uniform filament is produced, ready to be attached to the motorized spool for automated processing.

With this approach, we hope to contribute to the reduction of plastic waste while simultaneously providing a sustainable source of material for 3D printing, especially for students at Cooper.