Yesterday I was running a lot of ReCube parts. The first run was the shipping caps which are simple 2-wall extrusions. Meters and meters of filament just oozing perfectly in sync with the motion. Next I ran the pin protectors and noticed they were a bit 'thin'. Functional but off if you get my drift.

This morning I disassembled the recently maintained B2B nozzle and nothing out of the ordinary in the extruder itself but the tube did have a tell-tale anomaly. I don't have a coined 3D printing term for this, but it is related to a 'donut aperture' which I've tried to explain before. Basically it is a large melt zone (diameter 3mm or so for Cube3) right at the tip of the end of the tube, beginning of the extruder nozzle. This happens when a PTFE tube is too short. What happens is that the melt hardens at the edges and essentially the filament material becomes the 'tube'. The inside diameter of this tube varies based on temperature and flow (the ability for the heater to keep up). There are other terms for this but we'll stick with this one.

Yesterday's failure was along these same lines. There was no gap to fill at the end of the tube but the long continuous printing of all wall had somehow started a similar 'tube-like' non-melt zone about 1/4" long along the very end of the nozzle PTFE tube. I am certain this is a quality of the filament itself as well which is 3D Solutech Real White PLA in this case. Basically, this non-melt 1/4" long PLA 'tube' became a restriction in the prints.

This is an odd one and not something I've experienced 'knowingly'. But I have seen similar conditions as described earlier. Therefore, if you see thin prints, give you extruder a little maintenance and backtrack how you got there. This tip might just get you past a particularly frustrating anomaly.

Happy Printing!