@Chris_Smith 's printer finally prints for the first time down at the hackerspace. Been working on this for a little while along with @Mark_Hindess and Chris.
Thought it had Z lift for a while then noticed it’s actually pulling the nozzle toward the extruder on retract. Not sure how it’s doing that yet, I’m sure it’s all tightly mounted, it might be that it’s mounted on its heatsink and that is flexing.
http://www.youtube.com/watch?v=CZl32pjQjJ8
That used to happen to me when my extruder wasn’t bolted down firmly to my x carriage. The extruder can exert quite a bit of torque, so you really have to make sure things are tight.
Is that the Eckertech hot end? It typically bolts firmly to carriage - I’d expect to see no movement of the thermal barrier/plate.
The only time I had that issue was two hot ends ago when I had a PTFE based hot end that softened and was getting pushed/pulled by the extruder pressure.
Actually - watching that print, I wonder if that would be a viable feature to design into a hot end? It would give the same effect as z-lift but right at the nozzle…
@Rob_Antonishen I was thinking it could be rather desirable, if it didn’t fatigue the alu heatsink. Maybe a spring loaded hod end would be good, might make the retract more persistent too…
I ran two big bolts through the extruder, the carriage and down through new holes in the heat-sink. I think the nut compressing the extruder and carriage has come loose.
We did have the Eckerteck extruder and carriage before, but they had issues so we replaced it with a Greg’s.