Good starting filament printer?

[homebrewed]

I'm not saying it's impossible but your filament making idea may be more challenging than you think. Melting down a bunch of cut-up plastic bottles will introduce lots of bubbles that will be difficult to eliminate. The resultant filament will have varying density, which in turn will result in erratic delivery rates of hot plastic and subsequent poor printing results -- so it's really important to get rid of bubbles. It might be possible to de-air the precursor by using a vacuum system but it depends a lot on the viscosity of the melt. Raising the temperature will make it more fluid but that might cause it to break down & alter its printing characteristics.

You need to look into the molding techniques used to make plastic bottles. The precursor probably is in pellet form, pretty similar to what you will have, yet the molded bottles have few (but not zero) bubbles.

Another thought. A centrifuge loaded with the plastic, then heated to the melting point, could expel the bubbles. There are a number of build logs for centrifuges (centrifugii??) that clean up used cooking oil for bio-diesel that could be a starting point. Since all you want is to de-air the plastic you don't have to worry about the sludge. Unless your bottles have PSA-attached labels on them.

 

[Lex_Peacekeeper]

so the plastic is not being fully melted down, its getting to the glass point so it can be reformed,
heres a video on one of these units running, though its pretty short

 

[homebrewed]

so the plastic is not being fully melted down, its getting to the glass point so it can be reformed,
heres a video on one of these units running, though its pretty short

Interesting gadget. Sort of a 3D printer in reverse.

Thanks for the video clip.