Thermal Runaway?


If the printer does not recognize, that the temperature doesn’t rise in a predefined time, it’s called thermal runaway.

Marlin and other firmwares on the market do recognize, if the temperature doesn’t rise in an amount of time. So why bambu not?

Did you miss this part or do you just disagree with their logic?

"Why do we set it to 3 minutes instead of 3 seconds?

Because a very sophisticated thermal mode in the MCU is challenging, and it is difficult for the system to understand external uncertainties. Perhaps the silicon sock has been temporarily pulled off, or the user is tinkering with the hotend, maybe trying to unclog it with some metal tools which drain heat from the hotend. Since the system is safe and there is no fire hazard, we set the protection to 3 minutes to avoid false alarms ruining a print."


Maybe you want to read my response here:


I think 3 minutes are way too long.
On the german facebook group one guy pulled out the thermistor of the toolboard, the temperaturereading dropped to zero, the hotend fan turned of, but no error in a couple of seconds.
I think after 5 seconds of this hard temperature drop, the printer should display an error.
And by the way, it shouldn’t turn of the hotend fan!

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Agreed that 3 minutes us definitely too long.

In addition, can you verify that there is sufficient thermal runaway for the heat bed? It’s hooked up to mains and this would be a much worse issue if not implemented


Is it still work in progress, or has BL reduced the 3 min detection time down to a smaller number, like maybe 20 seconds, or possibly even less?

Thermal runaway can happen for a host of different reasons, but the main one is probably your temperature sensor within the thermal label printer, the thermistor, is misaligned.