Hello,
I've got a 1000mmx1400mm aluminum bed in an enclosed chamber with a 4400 watt heater on a Duet 2 WiFi running RRF 3.4.0.
I've noticed that when running autotune (M303 H0 S100), the first few measurement cycles take significantly longer to oscillate between 95 and 100 when compared to later cycles (which can take advantage of a 20C increase in chamber temperature, just based on how long the heater has been active) which are much shorter. As a result, when the tuning completes, it warns me that heater performance has been inconsistent and provides the new tuning values. When I apply those tuning values and run a print from a cold bed, it always throws a heater fault, presumably because those tuning values are favoring the later heating cycles during the autotune, which are taking advantage of much warmer ambient temperatures when compared to the beginning of the cycle, and thus the firmware is expecting it to act as if ambient is 20C warmer than it actually is.
My question is this - what is the technically correct way to account for this during the tuning process? I have had some success just leaving all of the doors on the enclosure open to allow the heat to dissipate during tuning, but it seems like there should be a more elegant solution.
Any tips are appreciated,
TIA!