Making 3D print filament with HDPE

Hi Precious Plastic community!

I have been looking through the forums to see if this is already being discussed but was unable to find a recent topic so sorry if this is a repost….

I am working to recycle HDPE plastic into filament and have been able to successfully print with the filament but some issues with a consistent diameter and bumps in the filament (see picture). Has anyone had success with HPDE extrusion that is willing to share some advice? Thank you in advance for your help!

inconsistency of diameter can be solved using the puller-roller assembly as ahown in the beta filament maker. i don’t know if or not you hve made and used it.
bumps was a surprise. theoretical it shouldn’t happen. i guess you should shredder plastic in even smaller pieces, i guess i don’t know the exact reason for it to happen

Can you please tell the specifications? It is looking interesting.

Impurities/contaminated material?