Heater Temp Falls down during print
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Heater 1 model: gain 472.2, time constant 252.2, dead time 7.7, max PWM 1.00, mode: PID
Computed PID parameters for setpoint change: P12.4, I0.049, D66.7
Computed PID parameters for load change: P12.4, I0.588, D66.724V 40W Heater
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https://www.dropbox.com/s/5tmygl7doud4fum/01.png?dl=0
what does this temp graph mean ?
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If the temperature shows regular oscillation while the hot end is heated but idle, increase the dead time (D parameter in the M307 command for that heater) slightly. If it only fluctuates when printing, that's normal if the fluctuations are small.
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Fitting a silicone sock to my heatblock stopped similar small variations I noticed, it's probably worth trying one (or kapton tape layers) to rule out stray drafts etc that can make temps wobble.
And remember that PID is a feedback system; so it will wobble slightly in response to changing demands (say moving from a big area of constant rate wall/top printing to suddenly printing a lot of support with more travel than print moves), or moving from the cold side of the heatbed to the side out of the drafts, etc.
Each time the load on the heatblock changes you will see a small fluctuation before the controller brings it back to stable, and tuning PID's is a compromise between getting the fastest possible response, but without overshooting and possible oscillating around the set temperature without stabilizing.
