Thermal runaway, printer keeps "printing"
Hello all,
I just tried printing with NylonX and was surprised at how easy it was, despite all the warnings that it took some time to get it dialed in.
I started out at 260/70 and everything was going fine until the 55 minute mark, where I had a thermal runaway error. The hotend shut down and started cooling, but the printer kept going like nothing happened. I only realized that something was wrong when I saw the camera feed was showing some problems. When I got down to the printer in the basement, the nozzle was about 3-4mm above the model surface, so it had been going for a while after the error tripped. Is this normal behavior?
Anyway, I thought it was a fluke, never having had this before, but it happened again at 55minutes. I've attached a screen grab of the temp graph from Octoprint of the event plus the few minutes leading up to it.
Printing in an enclosure (temp ~25c). For the first error, I had the enclosure door closed; for the second, I left the door open.
I flashed firmware 3.9.0 for MK3S a couple days ago, as well as 1.0.6 for the MMU2S. Would really like to troubleshoot this without wasting a ton of the NylonX at $100/kg.
_Erik
RE: Thermal runaway, printer keeps "printing"
Have you tried a PID calibration at the higher temperature that Nylon needs?
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: Thermal runaway, printer keeps "printing"
Have you tried a PID calibration at the higher temperature that Nylon needs?
regards Joan
No, I have not. I haven't done a PID cal since months ago.
I'll try that and post my results.
_Erik
RE: Thermal runaway, printer keeps "printing"
Okay, I did a PID calibration at 260, and tried to print the nylon model again.
About the same situation: every 5-7 minutes the temp would warble by +/-2c. Twice it dropped down -20c and recovered. The final time, it dropped down to 238c and stayed there for about 10-15 seconds then threw a thermal runaway failure and shut down the hotend. For the 5 or so minutes between warbles, it was rock-solid at 260, +/- 0.2c.
First pic is the first 30 minutes of the print, second pic is the last 30 minutes; there's some overlap, as the entire print took ~45 minutes. The initial drop at the beginning of the first pic is the temp shutoff as the filament failed to load with the MMU.
RE: Thermal runaway, printer keeps "printing"
Can't upload two pics in a single post, so here's the second
RE: Thermal runaway, printer keeps "printing"
Okay, I tried again, printing off the SD card to eliminate Octoprint issues. I don't have a fancy graph, but watching the printer, I can identify when it happens before the temperature drops. The temp looks like it's holding steady at 260, then all of a sudden, the cooling fan spins up big time, and the temperature plummets. It's actually pretty impressive how it can drop the temp 20c in a couple of seconds. So as the graphs show, there's no rise to provoke the fan coming on as hard as it does, but even if it did, the thermistor is reporting a rapid drop in hotend temp and the fan keeps screaming anyway.
Would really like to get this sorted.
_Erik
Oh, and the fact that the print kept running after the thermal shutdown is on Octoprint. When printing from the SD card, the printer killed the print immediately. I'll raise that part of the issue on the Octoprint forum.