September 7th, 2013  I mounted the extruders, turned on the heaters and attempted to run some filament through them, only to find that the barrels were getting hot enough to melt the filament causing it to clog. A little research revealed that this is a common problem with the QU-BD extruders. This lead me to make the following mods... Replace the QU-BD delrin feed block with the spring-bearing tensioner (I printed one set, then mirrored the STL and printed another)...