"Thermal Runaway" error after 1st layer, every time, after MK3s upgrade
 
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"Thermal Runaway" error after 1st layer, every time, after MK3s upgrade  

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Carol
(@carol)
New Member
"Thermal Runaway" error after 1st layer, every time, after MK3s upgrade

So the MK3 to MK3S upgrade went fine on my first one, but I wasn't so lucky with the second printer.  I get at "Thermal Runaway" error a couple of minutes in...it's always just after the first layer finishes.  The side (hotend) fan starts up and the temperature drops rapidly (from 215 down to 160-ish) and then slowly starts to climb, but it only goes up a little bit before the error hits and everything stops.

Here's what I've tried so far:
Upgraded to the latest firmware (actually, I've tried all of the 3 most recent versions)
Checked all connections...they're good.
Set the temperatures for the first layer and the rest of the print to be the same (210; I'm using PLA)
Ensured that the several gcode files I tried worked fine on the other MK3S (they do)
Re-ran the calibration wizard...everything checks out fine.

 What's going on here?  I see over on the GitHub forums that there are a lot of people having this same issue.

Posted : 15/05/2019 8:38 am
peter.l22
(@peter-l22)
Honorable Member
RE: "Thermal Runaway" error after 1st layer, every time, after MK3s upgrade
Posted by: carol.t2

 What's going on here?  I see over on the GitHub forums that there are a lot of people having this same issue.

What's going on is that there's enough cooling air hitting the build plate that the heater can't keep up. This triggers the thermal runaway because the same symptoms (i.e. heater on full blast and the plate not getting warmer) can also be caused by a faulty sensor or a broken wire to the heater.

The solution is to adjust your filament settings to disable cooling for more layers; or turn down the max fan speed to something like 50%. That will keep the cooling fan from blasting air right at the build plate.

Posted : 15/05/2019 3:57 pm
tj
 tj
(@tj-2)
Trusted Member
RE: "Thermal Runaway" error after 1st layer, every time, after MK3s upgrade

i had the exact same problem with my mk3s
my workaround in the beginning was to reduce the fan speed to around maximum of 70%

i also had problems sometimes getting first and second layer to stick, probably due to beginning of second layer when fan comes on and temp drops a lot the layers don't stick well together.
so my workaround for that was a bit of after layer change gcode to wait for temperature to stabilize before continuing with second layer.

but once i got one of those blue silicone sockets to put over the hotend all my problems went away.
hotend temp is much more stable when fan turns on and i have no more issues with flex material bridging (high temp + fan suddenly turning on = thermal runaway)

one of these:
https://e3d-online.com/v6-silicone-socks-pack-of-3

Posted : 16/05/2019 9:27 am
nrth3rnlb
(@nrth3rnlb)
Active Member
RE: "Thermal Runaway" error after 1st layer, every time, after MK3s upgrade

I use Kapton Tape instead of Silicone Block.

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Posted : 31/05/2019 1:32 pm
Nikolai
(@nikolai)
Noble Member
RE: "Thermal Runaway" error after 1st layer, every time, after MK3s upgrade

High speed second layer together with 100% fan and cool environment can cause this.

+1 for silicone sock and the issue should be gone.

Often linked posts:
Going small with MMU2
Real Multi Material
My prints on Instagram...
Posted : 31/05/2019 10:18 pm
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