Survey, How well does your bed temperature regulation work?

[ChrisA]

I'm looking at the code and docs related to AC mains-powered bed heaters. I see some room to improve the control algorithm but first I'd like some data. My bed heater uses DC and the control is nearly perfect so if you could tell me about the performance of your AC-powered system I'd appreciate it.

What size is the bed? How many Watts is the heater, is is 110 or 220 volts? 50Hz or 60Hz. and do you see ANY fluctuation in temperature? Does the fluctuation depend on the temperature setting? In other words, is higher better or worse than lower? Have you adjusted the PWM frequency?

What percent power does the bed run at? Are you maintaining 80C at 20% power or at 60% power? Does the percent power remain constant?

What I am looking for is sflow oscillation where the bed runs over or under the set point by 0.3 or so degrees.

I suspect that Voron printers have very stable bed temperatures because they use very thick and massive aluminum plates.

But I look at the design and think the worst case is a high-wattage heater set to low PLA printing temperatures with the panels open to allow exchange with room air. How does this work for you?

 

[NoGuru]

I was just doing some testing so here is a SS of my bed as it heat soaks

 

[ChrisA]

I was just doing some testing so here is a SS of my bed as it heat soaks

So it takes 37% to hold the bed at 105C. What size bed and what heater are you using? I assume it is a 110 volt Does it stay right on 37%

 

[NoGuru]

So it takes 37% to hold the bed at 105C. What size bed and what heater are you using? I assume it is a 110 volt Does it stay right on 37%

It's a 350mm. Yes 110 volts, and I think its a 750w heater.
And No, it does not stay at 37%. That changes a bit since airflow and probably from heat loss out of the chamber but if I had to guess I would say it stays within a few degrees or cycle of that.

I have not done a bed PID tune in maybe a year or two and I am not sure there is any loss in performance since the first PID tune. Maybe I will run one this weekend to see If I notice any changes.