Insight on how heat absorption is calculated  

Insight on how heat absorption is calculated

Hey folks - not sure if this was posted before, but I have seen tons of posts about why it does this, as well as some incorrect methodologies of just measuring the top via an IR camera.  I was poking around in the firmware source trying to find a way to fix the Extruder 1 heating when loading filament in another head, and ran across this code:

uint32_t BedPreheat::required_preheat_time() {
    if (thermalManager.degTargetBed() < minimal_preheat_temp) {
        return 0;
    } else {
        int32_t time = (180 + (thermalManager.degTargetBed() - 60) * (12 * 60 / 50)) * 1000;
        return time > 0 ? time : 0;
    }
}

As you can see, the heat absorption time is calculated from the target temp only and not the current temp. So while I could be misreading this, it does appear that the time is not based on the current temperature, which is interesting.  The 60/50 conversion is also interesting, as I can't think of why you would do that unless you were trying to convert from US power grid at 60Hz to EU power grid at 50Hz which should be irrelevant for this.