Is the end of the PTFE perfectly flat and without an internal taper? You haven't taken a drill bit to the end of it have you? I can see an external one...
Yeah it's perfectly flat, and no i haven't taken a drill bit to it. I've tried a flat end and tapered end. I've just stripped, cleaned and reassembled again making sure the nozzle is tightened properly against the heat break, and again it blocked. It's a shame because i know from the i3 MK2 they work very well.
Just a long shot, but try putting your nozzle size down to 0.35mm, set your extrusion width down to manual, 0.43, as a quick and dirty test that doesn't need too many changes. Also check your extruder steps/mm - do an extruder calibration.
I am having a similar experience. E3D V6 on delta. Worked fine for nearly a year and now it jams. Mine seems to jam at the upper end of the heat break. So somehow the heat is getting up into the heat break. I have all authentic components, stock fan, etc. I have changed out all the parts so one would think it has to do with my settings. Higher temps tend to make it happen faster. So far no luck in finding the root cause.
I can only suggest at this point that you look at a) making sure that the heatsink is clean (not dusty or clogged as this will affect the cooling effect of the stock fan), b) that the fan is not working at reduced speed (it needs the full 12v) or the bearings are dry or sticky c) The fan shroud has not come loose and the fan is not being as effective as it could be d) the heatbreak might need disassembling from the heatsink, cleaning, and reassembling with some new thermal paste, and making sure it is tight. Poor thermal connectivity between heatbreak and heatsink will definitely mean that heat gets to the top of the heatbreak. Hope this helps to some extent Edit: I should have thought of this earlier -doh!! How long are your retractions? Is there the possibility that you might be pulling hot plastic back up into the top of the heatbreak where it cools rapidly and jams? Prompted by your comment that higher temps make it happen faster - possibly because the filament is still molten longer, and retraction settings that worked before may need some tweaking to compensate. The only things I can think of are shorter retractions or lower the retraction speed Please forgive me if I am preaching to the converted here
I have been working on this problem for around three months. The V6 was working great for nearly a year and then it seemed suddenly to not be able to work at all. Last night I ran with no retractions and I still developed a clog. Then I set my nozzle size to .35 (from .4), still clogged. So now, since it is not making sense, I am looking at my extruder. I have been using the EZR extruder that came with my SeeMeCnc Rostock max. It seems it might not be providing enough force to push the filament. When I pull the filament from the bowden tube, the gear marks are very shallow, less than I remember. Just for fun I did another experiment. I made a small deflector that directed most of the fan air to the lower part of the heat sink. Since that is the part that needs the most cooling. I figured air at the top of the heatsink was less useful. It did not solve my problem even though the lowest fin on the heat sink was cooler to the touch.
Just a long shot, I assume the printer has a Bowden tube feed from the extruder to the hotend, so what is the internal diameter of the tube, is it a close or loose fit with the filament, because if it is loose the filament will behave like a spring inside the tube and cause unpredictable extruder control such as producing larger retractions or retractions even if you did not set retractions. Ideally, the internal diameter (ID) needs to be very close to 2mm leaving about 0.25mm of slack; some Bowden tubing can have a much larger ID but with the same OD and can create problems especially with flexible filaments.
