well it was 2.5mm @ 6mm speed, tried a bunch of different retraction amounts, if I hit 1 it would jam after only a few layers, if I went more, it would eat the filament with the hob bolt. 1.5-2.8 worked on the budda, and it used to work on this one, I have printed LOTS of nylon with it, but that was at a much higher temp, and jams were rare, delamination and print warping were the problem with nylon.
On the E3D forums I found that the “temporary” solution was to oil the extruder tube, but that would only last for a short while, cusomers saying only 1 print.
I noticed that the filament would jam at approximately the same duration depending upon the retraction, temp and speed of the retraction, but the result was the same in all cases, the end of the filament would get stuck somehow and upon retraction, would form a hard pill that became wider than the throat leading to the heater block, and the filament would get crooked and then the hob bolt would strip.
The filastruder rep tried to blame rapid, multiple retractions in an email, but also stated that the oil fix wouldn’t last long either. I found that the rapid retractions on pillar supports generated by Meshmixer caused some jam and strips, but the most recent wave of failures were on continuous flow prints that at first would go a while (2-4 hours) but if the head was already hot, and it stripped, the amount of time till another failure was shorter and shorter which fits with what I was pulling out of the extruder body, a filament with a crooked zigg-zag from the extruder motor pushing and it not going anywhere with a large bit of filament like a ball on the end, while on others it was a separated bit that seemed to stay jammed in the head, while the filament pulled away from it, which lead to a jam in a few more retractions, 1-3.
Either way it looks like the design is flawed, I hope the reprap one uses wider fins and a bigger fan, I’m thinking about trying that one next and in the meantime going back to my Buddaschnozzle with it’s PTFE guide tube. I found this on the forums which looks specifically at the 3mm E3DV6 and an issue with the feed tube diameter.
The forum link is: http://forum.e3d-online.com/viewtopic.php?f=13&t=177&start=90
it looks like a manufacturing problem they may have made the end of the tube too small, the fix would be: enlarging it to 3.3mm all the way through and removing a small step that remained from machining.