Printer stop extruding after one hour

I'm printing with PLA, 210 ° x 1.75 filament.

Print start without problems, but after one hour of printing extruder stop extrude and thE hobbed bolt "knocked" the filament.



I set slic3r several times with new settings, like temperatures, step per unit ecc ecc..

When I stop the printer and manually extrude I have to "help" the filament pushing it down because it's like blocked into extruder..

If I wait some minutes filament "turn on" and start working perfectly...... but if I start printing after some minutes extruder stop extruding! After some attempt with manually extrusion, filament doesn't make (not eaven) the first layer.

I'm using a bowden extruder E3D Chimera, I have the same configuration in other printer and works perfecly.

Help me!!!

(PS Filament is 1.75 but if measured is 1.6)

Try to reduce the retraction length or even print once without retraction.
Seems to me, you pull the filament into the cold zone of the hotend, where it jams.
Perhaps you also have cooling issues, because it only happens when the heat creeps up in the heatsink.
-Olaf

I tried with retraction..E3D docs talking about 2mm max and I'm working with retraction disabled.

When I have changed thermal paste on my hotend heat-break I've used a old one I think exipred...it's possible this paste is causing that?

Thank you

Overheating extruder stepper motor driver perhaps?

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Quote
dc42
Overheating extruder stepper motor driver perhaps?

I turn tripmot to min position and re-setted it for reach the correct force of the stepper motor..

I changed the thermal paste with a new one..look better!!