Thermal Runaway as Specific Layers...Why?
I was printing a 8 hour print (PLA) and about 2 hours in I experienced a Thermal Runaway. This is on a I3 MK2.5S. The second image shows where that occurred. I started the print again and kept checking it and when the same layer started, the nozzle temperature began to drop. I wiggled the wires with no results. I paused the print and reheated. I restarted and again the temperature immediately began to drop. This time I dropped the set point from 210 to 190 and watched. The temperature stabilized at about 187 and everything kept going fine. I slowly began to raise the temperature setpoint a couple degrees and watched to see if the feedback would change. Slowly it started to climb up. I was eventually able to get back to 210 and let it run. The first image was at about 7 hours in and another Thermal Runaway occurred. Unfortunately I was unable to catch it and lost the print. Hopefully you can see in the two images that the print was at the point of creating the first base layer on top of the infill. I had my nozzle fan set at 10% min and 20% max because I've had a lot of failures due to over cooling. I also turned off, or left the field blank, for full speed fan after XX number of layers. I've torn my printer down several times and never been able to find a compromised wire. I don't know if there's another setting in Prusa Slicer that I can change to prevent this. I sure wish the thing would alarm before faulting! At least I could pause the print and reheat before continuing. Also, I'm several versions of firmware old. I loaded the latest firmware and had lots of issues trying to print. I had to go back several versions to get one that would allow me to print at all. Any ideas what's going on? This is killing my print time!
RE: Thermal Runaway as Specific Layers...Why?
Well, in case someone else reads this with a similar issue, I figured out the problem. In Prusa Slicer, under the <Filaments> tab, there is a setting for <Bridges fan speed>. After studying all the settings for a while, I discovered that this setting was at 100%. I dropped it to 20% and no more issue! I've had a lot of issues with cooling over the years and done a lot of experimenting. I cannot run with the default fan speeds. I always change them to Min 10% and Max 20%, but that doesn't account for the bridges. So now that I understand what was happening, and I know there's a setting for it, I think I shouldn't have any more issues! Good luck to anyone that has temperature issues. Message me if needed and I'll look at my settings to see what might be causing your issue.