Thermal runaway layer 2
Hi,
I have a strange thermal runaway :
It prints the first layer perfectly, and as soon as it starts layer 2, the nozzle temp starts to drop until the printer stops and indicates "thermal runway".
I have done several prints, and it is always the case. When layer 2 starts, i tried to adjust manually the nozzle temperature, but it ignores it and keep dropping.
If it was the thermistor i guess it would not work for layer 1 as well, so i'm a bit lost here,
Any idea ?
Happy print !
RE: Thermal runaway layer 2
Sounds like the part fan kicking in at layer 2 is causing the heater to cool too rapidly. The simplest fix is to fit a silicone sock. If you dont have one they are a good idea to fit anyway as they can potentially help if you have a detached print resulting in a blob of doom'(tm) 🙂 They also stop the rapid cooling.
Another alternative if you are using slicer 2.3.x is to change the cooling settings under your filament profile. Theres a new option for Full fan at Layer x. That ramps the speed up gradually. Set it to something like 3 or 5 and try a print. The sock is a better option though.
RE: Thermal runaway layer 2
@neophyl
You are correct. Searching, i found a note from Prusa about it. I don't print PLA usually so i don't use fan or 10/20%. And this time i tried to print with PLA (and 100% fan)...If fan is OFF, it is fine.
But i can't say this is FINE. The printer is a MK2.5S. I will try a sock.
Have a nice day !
RE: Thermal runaway layer 2
What kind of temperature drop are you getting ?
is it just a few degrees and then it rises again or does it just go down without recovering back to target temps ?
i have been printing with pla quite alot, and i have seen dips (a degree of 2 to 4) when the fan kicks on, but then in the span of a few seconds it goes back to target temps. i have not seen the thermal runaway error yet.
a sock does help it stabilize, but if it can't catch up it might be another issue.
if you are using octoprint you have a nice tempgraph, it might illustrate your point better.