freaky printhead jam

[Geertjan]

That looks exactly like my printhead jam. I still don't know what caused the jam.
But the base plate of the printhead was also deformed as a result of the heat.
I am still don't know what caused the extruder to fail. One probable cause is that the cooling stopped. In combination with an extruder jam, which usually results in filing of the filament, the filament became warm enough to deform and crumple up.

[satoer]

Maybe a solution: implement a second thermistor. If the temperature difference between them is more than 30 degrees the firmware will disable the heater. this shouldn't be hard to implement I think.

I've been hacking into the firmware... turns out this option is already available in the latest Marlin firmware:
https://github.com/ErikZalm/Marlin

In configuration.h:

Code: Select all

// This makes temp sensor 1 a redundant sensor for sensor 0. If the temperatures difference between these sensors is to high the print will be aborted.
//#define TEMP_SENSOR_1_AS_REDUNDANT
#define MAX_REDUNDANT_TEMP_SENSOR_DIFF 10