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False thermal runaway on wide, flat print  

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Alexi
(@alexi)
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?

Best Answer by Neophyl:

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 5:16 pm
Neophyl
(@neophyl)
Illustrious 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
Alexi
(@alexi)
Active Member
Topic starter answered:
RE: False thermal runaway on wide, flat print

 

Posted by: @neophyl

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. 

Thanks, just got my silicone sock and that solved the issue. Really seems like this is something that could be fixed in firmware, and now that I know what to look for, it seems like it's been an issue for a while now. Odd that it hasn't been solved.

Posted : 25/05/2022 12:37 am
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