UPDATE - this is working REALLY well - the pressure adjustment SUCKS but otherwise - I literally only have to adjust it if I'm changing filaments (which means they change diameter slightly) I'm working on a replacement assembly for the filament extruder body - will post pictures when it's closer to done. My main goal is to minimize EVERYTHING! pathways, plastic used, size, etc... can't wait to share!

OK - the theory was sound.

In practice? - yay, it works!

The following is a rigged up kinda like the paxtruder teflon idler not-a-wheel, wheel.

Prototype version - (note there are actually 3 pieces of scrap PTFE tubing, 2 for stabilizing, and 1 pressing against the filament - and this only worked for a while before the tubing started slipping)

Above is the current and PERFECTLY working version - a relatively simple retrofit of the MK4 Plastruder. The tensioning mechanism leaves a bit to be desired, however I have yet to have to adjust it and it's going on 2+ weeks of good printing (basically it's 7/3 right now and whenever I first posted the original post... ) --- also note the makeshift needle that shows if my motor is turning... it's just one of the little cone/piles of filament popped into the bearing hole. works like a charm.

Basically I flattened a piece of scrap PTFE tubing from the stuff I'm using to line the heater barrel. WOW this works - um... 100,000,000X better than the idler wheel IMHO.

the piece of flattened PTFE tubing on the near side (and another one on the back) prevent the idler from getting pushed to one side by the filament... and yeah that's a printed (failed) IDLER wheel.

Above and below here are the mocked-up extruder with PTFE lining.

• 5/16"-18 threaded hollow steel pipe (3/16" ID, and right now it's 5" long... TOO long. I need to shorten the actual "hot zone", but this proved a point.
• 3/16" OD, 1/8" ID (3.125 mm) PTFE tubing... with about 0.002-0.005" shaved off the outside to allow it to slip inside the hollow tubing without having to FORCE it in - which doesn't work when it's net fit.
• the rest is just for mocking up the extruder (the wooden blocks actually work really well over the metal - they insulate and really don't get THAT hot. (of course it's wood - so if you use wood on a heater barrel - do so at your own risk, as I didn't build your heater barrel, I don't know it's risks.

Yeah, I KNOW WAY too much plastic - but at the time it was better than NO plastic :D