Testing Extruder Temperature
Hi
I've had to replace pretty much all of the extruder and have replaced the heater cartridge and thermistor, but the filament is still having issues going through the extruder. I just wonder if there is a way to test the temperature of the hotend to prove that the thermistor is working correctly? How do I check I have the correct one thermistor? The heater cartridge has it engraved on it, but there's nothing on the thermistor.
Thanks
Steve
Re: Testing Extruder Temperature
Hi Steve,
The thermistor changes its resistance with temperature (the resistance falls as the temperature goes higher). The RAMBO board reads the resistance and converts this into a temperature reading. Different thermistors have (significantly) different resistances for the same temperature. From memory the E3D uses a thermistor that is around 100,000 ohms at room temperature (25 degrees usually). Different thermistors will have different resistances at the same temperature, for example the next 'range' thermistor has a resistance of 10,000 ohms at 25 degrees.
The upshot is if you get a room temperature reading when the hot end is at room temperature the chances are the thermistor is ok.
To double check leave an independent thermometer on the printer and leave the printer off for a while (say over night). Now the hot end, heat bed and the thermometer will all be at approximately the same temperature. Turn the printer on and the main LCD display will show the current temperature readings from the thermistors in the hot end and heat bed. If these are within a degree or so of the independent thermometer the chances are your hot end thermistor is OK as if it was the wrong type the value indicated on the display would be wildly out.
Hope this helps
Re: Testing Extruder Temperature
Thanks that's great, I'll try the room temperature trick and see what happens.
Steve