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False thermal runaway on wide, flat print  

Active Member
False thermal runaway on wide, flat print

Hi all, I have a Prusa i3 MK3S and I'm running into a strange issue where the printer throws a thermal runaway error on a specific print in a specific spot. The print in question is very wide and flat, and the error occurs about 1/3 of the way into the second layer, where I imagine there is some sort of temperature transition that causes the printer to think there is a thermal runaway. I've tried re-slicing, but I get the same result in the same spot. I'm pretty sure there is nothing physically wrong with my printer, since this is the only time this error occurs. I've been able to successfully print several other objects with no problems.

Has anyone else every run into this problem? Is there a solution?

Posted : 13/05/2022 5:16 pm
Famed Member
RE: False thermal runaway on wide, flat print

Firstly it’s likely caused by the nozzle temp dipping when the fan kicks in after the first layer (assuming you are printing with a default pla profile). The air gets kicked back up and cools it down. 
The simplest method is to fit a silicone sock on the hot end. That insulates it from the blow back. It also has the side benefit of helping with blob issues and general clean up. 
You can also tweak the temps and fan speed settings on the filament settings but the sock is a much better method. 

Posted : 13/05/2022 6:49 pm