Hi guys!
I made extruder by Dave instructions. But now I have problem with this machine. Plastic pieces don’t go to the front of tube. Everytime get stuck at behind.
If I clean tube and screw, it happens again. 
Pieces are PET (shreded by Dave shredder).
See my video with problem
I don’t know where can be problem. Please help.
Thank you very much!
It says video not available. (tip: if you just put the youtube link in your post it should automatically embed it) PET is a tough one to start of with. It’s either not molten or burned, you need to have your melting temperature very accurate. I’d suggest to give it a few runs first with PP or HDPE to understand your machine and later move on to PET
Good luck! 
Oh really? I thought, it must move forward without heaters… Now I’m smarter.
Thank you and have a nice day!
Ah you haven’t heated it up yet? The material will move forward once it starts to melt inside. No worries, just keep building 
Maybe now, video would be functional.
I try PET and HDPE (without heating elements). But every material get stuck on the start of tube.
PS
Thank you Dave for your impressive ideas. Your machines are great!