I ordered some carbon fiber filament and hardend nozzels for when I get my big box, but I already have a low end printer. To make a long story short the hardend nozzel is the same size and thred so I figured I would give carbon fiber a try. I layed down the first layer for a single walled print, looked like it would be fine but then it started under extruding, I don't think it was skipping steps it didn't hear the characteristic thump when it slips on the filament but maybe. The tried regular PLA and that is struggling too. I took out the nozzel found a metal flake that feel off the threads, thinking that may have been blocking the flow I put it back together but I still same results. I can push the filiment by hand just fine, can it be the hardend nozzel having differnt characteristics or something else? I can't even print regular PLA now, going to take the whole extruder part and put the old nozzel on when I get home.