I measured the offset between bed thermistor and print surface at various temperatures so I can define a linear or parabolic formula to scale the readings to obtain the “real” temperature.
Clearly the goal is to have the set temperature to also be the real one, without having to remember the offset, even more so when multiple printers are in use and each one has a different offset.
However, it’s not clear to me, after reading the docs about thermistors, how to do it, if it’s even possible.
I am aware of the Dual loop PID, but that’s a new feature based on two thermistors and which won’t likely make into mainline, the pull req has been closed already.
I hoped there was a way correct a single thermistor.
I remember from maybe 3 years ago that Octoprint offered some offset correction (I think), so I was looking for the same feature.
I guess I will have to manually calculate new thermistor coefficients to be put into a new custom thermistor, which in theory should work.
I would not mutilate the characteristic of the sensor.
Typically the offset is stable at a given bed temperature. E.g. on one of my printers, the offset is 13°C at 80°C → Need 93°C to reach 80°C on the bed surface, so I just work with this offset.
Personally I do not use a lot of different bed temperatures since the relevant bed mesh is also taken at the given temperature, so it was quite easy to define these static offsets.