Building on the post I made today: http://forums.reprap.org/read.php?171,34188
What about using a meat grinder? Something that worked in progressive stages, so that large objects to be recycled and something like a tree shredder cuts them down to smallish chunks।
I was thinking along the same lines as you with the meat grinder along with the reuse of a few other kitchen tools। I put some time into the idea of using a "dumpling pan" and further a "pasta maker"। http://probersideas.blogspot.com/2009/11/view-to-extrude-2.html.
Attacking it with a milling bit gives fine powder of course।
I ruled this out a long time ago। KISS, this is the key IMHO The problem with cutting HDPE is it is one of those plastics that gets stronger when you stretch it until it is incredibly strong and very very thin.
Use as a starting point various temps, within progressive stages to reshape and reuse the plastics for infill। The device would operate kinda like how they crush cars down to a chunk। For our purposes, the plunger will push the plastic into an extruder to “reform” the plastic into tootsie roll size, or the preferred filament size rewound into a spindle।
If I had the time would build it:?
Some possible Crusher plunger mechanisms
Both the French fry cutter, and Can Crusher mechanisms are similar. Might be great as candidates to quickly prototype a working recycler.