Thermal Runaway on Heated Bed

[jslick_007]

I'm getting a Thermal Runaway on the Heated Bed when I try printing at 110C on the heatbed. It'll go up to 97C without issue, but after about an hour of printing at 110C, the whole thing shuts down. The OctoPrint interface shows disconnected, but pulling up the terminal, I get "Error: Thermal Runaway, system stopped! Heater_ID: bed". Is there something I can check before sending the unit back to MakerGear? In the middle of a major customer print, so really trying to avoid having to send back if possible.

EDIT: I tried on my other MakerGear M3ID purchased around the same time, albeit from different resellers and it gets to 110C no problem, so it seems to be specific only to one of them.

[insta]

My suspicion is a loose plug. Make sure everything is snug.

Second suspicion is drafts. Upturn a large moving box over the printer and see if it still does it.

[ednisley]

"Error: Thermal Runaway, system stopped! Heater_ID: bed"

Marlin's default "runaway" hysteresis seem awfully tight at 2 C and, if the platform heater can't keep up with cool drafts. The heaters are on, but the temperature isn't tracking, so the firmware concludes the thermistor has gone bad.

That's a reasonable assumption, except when winter sets in and my Basement Laboratory cools down.

If the platform temperature graph looks erratic, then the thermistor may be going bad. If it's steady and slightly declining, then it's a cool breeze over the platform.

Bumping the runaway hysteresis to 6 C helped, as did increasing the time delay to 40 s. You must recompile the firmware to change those values, though, which may make cranking up the room thermostat look downright attractive.

Search for "runaway" to find the appropriate lines:
https://softsolder.com/2016/04/14/maker ... 1-1-0-rc5/