Thermocouple and overheating problems

[evaldas 0]

Hello everyone

I have been printing with ultimaker for cuople of weeks, until I've tried printing with ABS plastic. But ABS plastic always came out underextruded, as I figured it out the problem was jamming in hot end issolator tube ant nozzle. So Ive unscrewd hot end, cleaned everything and tried printint with PLA. At first it was ok, but after few minutes plastic started flowing in liquid shape. I stop printing to examine the problem, immediately after that smoke started flowing from nozzle and couple dripplets of burned plastic.

After that Ive noticed that thermocouple looks damaged.

 

So I think the problem is that thermocouple is'nt showing accurate results of temperature, causing hot end to constantly raise temperature, though inner wires doesn't look damaged and cura shows temperature I've entered at the begging ~220

 

Has anyone had problem like this? Is it fixable? Could there be another problem aside thermocouple?

 

[gr5 2,237]

Find out at what temp your heat block boils water. Set it to 90C, then increase by 5C until it boils. It should boil around 95C to 105C. If outside that range something is wrong with your temperature measurement system. It could be the wiring, it could be the small electronics board on you print head. It's usually not the thermocouple - but sometimes even that can go bad.

If the print head is just always 20C hotter than you could live with it and always print at 180C instead of 200C. If you go any lower than 180C you will occasionally go below 170C which halts the movement of the extruder.

Note that there is a spare cable for the temperature measurement. You can just switch to the other connector (at both ends - the print head and the board underneath).