Thermistor readings are way off

I have realized that my thermistor readings are wayyyy off.

I printed for or five "test" cubs today, gradually increasing the tempature, all the way up to 275c and each time the print quality improved...

e3d says that Semitec 104GT2 thermistor is the thermistor I have, and i am using marlin, so I changed my thermistor to 5 but it is still way off....

any ideas?


pps, at room temature, they seem to read correctly....

You could try PID autotune.

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Newbie with Folgertech 2020 i3.

from what I understand, that just affects how quickly the heating element heats up and its duty cycle, not the actual reading of the thermistor, unless I am wrong?

Quote
Qdeathstar
from what I understand, that just affects how quickly the heating element heats up and its duty cycle, not the actual reading of the thermistor, unless I am wrong?

Yes, you are correct. That wouldn't fix your issue.

You can do three things:
1. Get another thermistor supported by the firmware and see if that fixes the problem
2. Get a thermo couple and digital volt meter that has a temperature function and compare the thermistor readings with the DVMs. You can change the thermistor table until it matches the thermocouple
3. Get a thermo couple board and thermo couple, change the firmware to use the correct thermo couple board. Readings will be within 2 degrees C accuracy.

I think i will try option two.. I wonder why the thermistors aren't correct though....

Where should I measure from? It seems like I get a different reading depending on where I measure... Like a 10c difference.


What's going on with these prints?

I would stick the thermo couple through the top all the way down to the nozzle. Clean out the filament first That's the most reliable and sensible place to measure the temperature.

As for the print, I think it's related to anything on the path of the filament, from roll like entanglement, through the extruder, check idler tightness, hobbed bolt properly aligned, nut, gear slipping, wrong temperature? Temperature not stable? nozzle partly blocked, dust or debris on the filament, particles in the filament, and finally what size nozzle? Below 0.4mm tend to block more often.

Edited 1 time(s). Last edit at 10/21/2015 12:47PM by imqqmi.

I am using hatch box filament, which has good ratings, and a .4 nozzle size.

I think I was extruding too low, so I fixed that problem and print quality improved some what, still some more work to do, I think those problems might be slicer settings though, from what I've read.