Thermistor readings are way off
October 12, 2015 10:52PM
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....
Re: Thermistor readings are way off
October 12, 2015 11:17PM
You could try PID autotune.


Newbie with Folgertech 2020 i3.
Re: Thermistor readings are way off
October 12, 2015 11:57PM
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?
Re: Thermistor readings are way off
October 13, 2015 12:20PM
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.
Re: Thermistor readings are way off
October 13, 2015 05:26PM
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.
Re: Thermistor readings are way off
October 13, 2015 06:12PM
I think i will try option two.. I wonder why the thermistors aren't correct though....
Re: Thermistor readings are way off
October 20, 2015 09:59PM
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?



Re: Thermistor readings are way off
October 21, 2015 12:46PM
I would stick the thermo couple through the top all the way down to the nozzle. Clean out the filament first smiling smiley 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.
Re: Thermistor readings are way off
October 21, 2015 01:07PM
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.
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