Hello everyone,
I have been printing in PLA for about a week now and everything was running well other than the extruder occasionally slipping a millimeter or so until last night during a very long print when the hot end jammed and it stopped extruding,
I unblocked it and tried again but it jammed again after about half a layer. This process has repeated a number of times now, with the temperature set at different levels between 185 - 205C. I have tried to push filament through by hand and it starts off easy but after 10 minutes it become impossible to move in or out. The hot end was cleared by pushing a small allan key in the top and very thin wire in the bottom.
I fear it may be side-effect of using a J-head clone from 3d printerczar that i believe is not built to specification in a few aspects but is generally close. Any ideas on what to do to get the current hot end working?
Thanks in advance.

On long prints heat can travel up the nozzle through the heat break, cause the filament to expand an jam at any contraction lower down. Pointing a fan above the heat break helps.

You can tell if this is your problem by pulling the filament all the way out after a jam and visually inspecting for swelling of the filament.

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