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My prints have been going fine until recently when the filament has started getting mangled in the extruder at the very end of a print. Once this happens filament stops going through the extruder and the very end of the print fails. I'm not sure why this is happening and why it is happening at the very end of the print. My best guess would be that the extruder is both hot at this point and maybe the fact that it is extruding slower makes it more susceptible.

This is pretty maddening because I'm doing 7 to 13 hour prints for my wife to use in programming for children. I still have some time to tinker but I'd like for them to have good stuff to work with. Does anyone have any suggestions?

One last thought I had was that it's the end of the roll and the tight winds at the end might be increasing the resistance for the extruder and magnifying the problem?

What material?
What temperature?
What speed?
What make motor is on the extruder (Wantai, or Kysan)?

I found my extruder motor was getting hot enough to soften the filament. Pointing a fan at it fixed the problem.

Here's how I fixed it: http://repables.com/r/453/

(Dunno if that's your same problem or not, but could be.)

I've been playing with it and might have fixed it. The PTFE tubing wasnt all the way down in the hot end and I think I was getting some jamming. There was a lot of pressure that seemed to be applied when I was running the filament through. I disassembled the hot end and cleaned it out then reassembled it and made sure the ptfe was all the way down and locked in place.

So far that seemed to fix it.

BenTheRighteous, where did you pick up power for the fan, and is it controlled or on full time? I'm guessing that some leads from the power supply could be used but I'm not sure if it should run all the time or not? I've been having issues with filament tangling, and this last time it happened I almost burned my fingers on the stepper motor.

I spliced the wires that run to the peek fan, so the new "extruder fan" runs whenever the nozzle is hot. That seemed to be the easiest solution and hasn't noticeably impacted the performance of the peek fan.