mhackney wrote:So this might be helpful to some and purely conjecture on my part until I experience it again...
I printed ProtoPasta CF PLA filament for about 2 weeks solid, 8 hrs a day to make the parts for my fly fishing reel kits. My big event was this past weekend. I shut the printer down before I left. I did not print all day Thursday, Fri, Sat, Sun or Monday. On Tuesday I ran into all sorts of problems with filament starving. The layers would go down with large gaps where filament did not extrude. Almost like there was grease or something on the PEI print surface. I suspected the extruder and/or hobbed gear. I tore them apart and things seamed better for 1/2 a print and then failed again. I ended up having to tear down my Kraken hot end. Inside I found a rock hard, black blob stuck to the side wall that took up most of the passage. There was enough space for some molten filament to get by but not a lot. I used a 2mm drill and carefully removed the plug by hand. It looked like the CF PLA. I shut down each night with the everything "loaded". I am wondering if maybe the CF PLA thermoset to create that blockage, it really was rock hard. Once cleared, I'm back to printing nirvana.
I have experienced the same thing - blobs inside the nozzle. I now have run about 2Kg through my machines (my own personal Rostock V2 and a Leapfrog Creatr at work) and both print great but occasionally jam with a blob. As a precaution, I now always push filament through the nozzle by hand once it gets to temperature and before actually trying to print. If it flows out easily I know there's no blob. Otherwise most all the time pulling the filament out and pushing it back in (again all by hand) will clear the blockage and pushing it by hand lets you feel whether it's partially clogged. The ProtoPasta CF really prints great!!