hotend entrance keeps getting plugged

Im having trouble in between prints with the top of the hotend getting plugged then on the subsequent print not feeding. I only ever print PLA. I don't understand why this is happening - my guess is that the filament is getting warm and somehow spreading into this void at the top of the hotend. It then firms up and stops new filament from entering.



How to fix permanently? I did wonder if there was a missing part such as an o-ring or piece of ptfe that is supposed to go between here and the extruder body?

Hi,

Are you leaving the extruder heater enabled for long periods between prints with the cooling fan disabled?

The only explanation I can think of is excessive heat-creep occurring under those conditions. Your end GCode should disable both heated bed and extruder heater at the completion of the print.

Another possibility would be printing at very low speed with lots of retract operations again without the cooling fan enabled.

Operating the printer under recommended conditions should not allow this to happen. It is something I have never experienced.

Regards,
Neil Darlow

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I try to write with consideration for all nationalities. Please let me know if something is unclear.
Printing with Mendel90 from fedora 25 using Cura, FreeCAD, MeshLab, OpenSCAD, Skeinforge and Slic3r tools.

Hi,

Is it an original J-Head? I had the same problem, after i replaced my broken original with a chinese clone. If the printing time was longer than about an hour I had the problem in the same place, but only by using PLA, not with ABS.
My solution is, that i use a piece of teflon inliner betwen the wades block an and the screw in the J-Head. Additional i mounted a little fan on the J-Head, to blow on the top of the extruder, similar to the E3D extruder. This fan is controlled by gcode. Now I have no more problems and the print quality is the same as before with the original.