Extrusion stops melting filament

My 3d printer was working well, and just yesterday my prints have been incomplete. I suspect the extruder cools down and stops melting the filament. After the first layer is laid down, the ant fill becomes random and when I manually use the extruder, the filament stops and when I pull it out some of it is melted and some are not–the extruder stops melting even though the temperature measured by Repetier is still at 190-200 degrees celcius? It is hotter yesterday in California so I thought that had something to do with it. My question is, do I need to replace the thermometer and how do I check if it needs replacement? Any other ideas what is going on with my machine?

Hi cheapcoconut,

from the temperatures that you mention you’re using PLA, right?

You can use any other thermometer capable of > 200 °C (or > 400 °F), e.g. one with a type K thermocouple. Heat resistant tape like Kapton can be useful for fixing the thermometer to the heater block. This kind of tape can also be used to cover the thermistor, so that it is less affected by airflow (A/C blowing towards the printer?).

If the hotend did, for whatever reason, heat up too much, it is possible that the nozzle is blocked by some PLA residue. Did you notice small black dots in the extruded material? Is the extrusion better (if only for a few seconds) when you clean the nozzle with a piece of wire or a suitably small drill?

About the thermistor, you can check its resistance (unplugged from the board) to assess whether it’s ok or not. At 25 °C, it should be 100 kΩ. If your room temperature is higher (lower), the resistance should be lower (higher).


Thank you for your response, it was quite useful. My printer’s thermometer is fine and the heaters are also doing what they are supposed to. I will post further printer problems still occurring.