What are the parts you need such a printer for?
Forgot to tag in +Peter van der Walt on the previous Openbuilds team tag
@Alex_Krause The concrete bit I started with had rather shallow flutes. I hand ground the flutes progressively deeper towards the start of the feed.
When printing that large, I wonder if you could use built supports covered with PTFE, to support large flat bridges? Might need some glue stick. 
The auger bit is going to give you poor flow rate control compared to a proper extrusion screw, but depending on what you’re trying to do, that may be ok.
may i ask of what size of bead or regrind can used with this or do the plastic have grind fine like coffee grown… ricklanden@juno.com / makerspace 757 of hampton roads virginia usa
Are there other open designs out there? I’ll build em all to try!
@Zviad_Sulaberidze Well done! I was working on a pellet extruder last year, but I got side-tracked with other projects. Are you planing on releasing the design?
yes, as soon as I get it working, I will put design
Where can we follow progress on this build very interesting
here, probably, I will put a progress here, time to times
@Robert_Rapplean1 screw speed versus nozzle backpressure. For a particular nozzle size, material, and temp, you can associate screw RPM with a particular flow rate. It’s actually much like the old RPM-based DC motor extruders before 5D was a thing. Or you can ignore all that and just treat the screw like an extruder with a wacky e-steps value, but you typically end up with crap volume control if you do that. (There’s a reason why non-spiral-vase hobbyist pellet prints usually look crummy.)