If you know that most soda bottles are made from PET plastic, you’ve probably thought about how you could make filament from them and have an endless supply of cheap printing material. [Mr3DPrint] says he has a method and shares a few videos that make it look easy. We wonder if the quality of the filament is up to par with commercial products, but assuming the videos are accurate, it appears that the resulting filament gets the job done.
The details are a little sketchy, but it looks simple enough. THe first step is to get any indentations out of the bottle. He has several demonstrations of this some using pressurized air in the bottle and some without. In each case, though, a drill holds the bottle through the cap and spins it over a flame until the surface is smooth.
Once mostly smoothed out, he cuts the bottom off the bottle and uses a mounted razor blade to cut the bottle into a thin strip. The next jig is a standard hot end with a 1.75mm nozzle mounted horizontally. We assume he drilled out a standard nozzle with a 1.75mm hole or, accounting for die swell, maybe a bit smaller hole.
Presumably, the razor produced strips narrow enough to fit the top of the nozzle. He pushes the plastic through and uses a printer heat break to tie it to a string and a little machine pulls the rest through while winding it up on a takeup spool.
Our guess is the diameter of the filament is all over the place and we wondered if placing the filament vertically or horizontally would give the best results. However, this seems like it would be an easy thing to cobble together if you wanted to try it. In the comments, [Mr3DPrint] mentions some temperature ranges to get you started, but we didn’t find any reference for the designs of the machines. On the other hand, they seemed simple enough to build, especially if you have a 3D printer.