Thermal Runaway Protection
So i know that Marlin firmware has the capability for thermal runaway protection, but after looking through the latest code on github ( https://github.com/prusa3d/Prusa-Firmware/tree/MK2/Firmware ) it appears to be commented out in the configuration.h file.
I did a quick search on the forum for thermal runaway and saw that at least one person seems to have experienced this issue (which is very scary to me). He even mentioned that it happened with the thermistor reading a very low temperature (under 30 degrees) which should be easily preventable with the right firmware.
Are there any plans to implement this feature in future releases of the Prusa firmware? If not, could you look into doing this? It will really help me sleep easier at night 😀 😀 😀
Re: Thermal Runaway Protection
The thermal runaway for the extruder is included in the variants file. https://github.com/prusa3d/Prusa-Firmware/blob/MK2/Firmware/variants/1_75mm_MK2-RAMBo13a-E3Dv6full.h
For some reason the bed thermal runaway protection is disabled in both.
Re: Thermal Runaway Protection
oh nice! I'm assuming that this configuration was used to generate the similarly named .hex files that come pre-compiled?
I was mostly worried about the extruder, so this is good to see. I could see the bed thermistor being damaged at some point, but i would think it would either fail open or closed - not simply become disconnected but still function. Is there protection in place for a damaged bed thermistor? I suppose i could go unplug it and find out 😀
Re: Thermal Runaway Protection
Kevin
The latest firmware (3.0.5RC) does have thermal runaway protection for the extruder at least as witnessed by Curtis (I think and one other user) on a thread he created.
However, the source code on Github for 3.0.5 is certainly different (when I last looked) from the hex file that was released and that version is currently being developed further according to Vojtech in one of his posts.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Thermal Runaway Protection
My first print with ColorFabb XT (240°/90°) on my MK2 resulted in a "THERMAL RUNAWAY" error on screen and the printer stopped and went into cool down... this is with 3.0.3 firmware... It was because the print fan only came on when it got to printing the top layer over the infill (bridging)... Once I turned of the bridging fan as well it worked perfectly...
Re: Thermal Runaway Protection
I can also confirm that thermal runaway protection is active and working. When changing my nozzle to a hardened steel unit recently, I heated the hot end per the instructions on the E3D website. When I put the wrench (spanner) on the heating block to hold it while I unscrewed the nozzle, the temperature started dropping due to the sudden large increase in thermal mass and the heating element just couldn't keep up. After a short period, "THERMAL RUNAWAY" was displayed on the LCD and the heating element turned off.
Roger
Re: Thermal Runaway Protection
Cold part of the hotend shouldn't exceed 55C I think. I'd stuff a bimetal thermal limit switch in there to cut power to the heater.
Same goes for the bed, but with a different trip temperature.
Trusting the firmware is neat and all, but... yeah.