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Thermal Runaway issue after upgrading Mk2 to Mk2.5  

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alasdair.m2
(@alasdair-m2)
New Member
Thermal Runaway issue after upgrading Mk2 to Mk2.5

If you see a drop by 5°C - 10°C when the fan is switched on (especially when the printer transitions from the 1st to the 2nd layer), it's normal. That being said, mine dropped just over 10°C and then slowly dropped until the THERMAL RUNAWAY kicked in. Is this just due to what appears to be the fan speed being at 255 and dropping. If there are any other solutions please let me know or confirm my thoughts. Thanks

Posted : 19/11/2018 3:12 pm
JoanTabb
(@joantabb)
Veteran Member Moderator
Re: Thermal Runaway issue after upgrading Mk2 to Mk2.5

Hi Alasdair,

is your e3dV6 installed in the correct location?

in the picture above, you can see the circular aluminium heatsink is level with the plastic housing,

does your heatsink prodrude further than this?if so, the top of the heatsink is probably not properly installed

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 19/11/2018 5:56 pm
alasdair.m
(@alasdair-m)
New Member
Re: Thermal Runaway issue after upgrading Mk2 to Mk2.5

I've just upgraded two i3 mk2 printers both with the previous incarnation of thermistor, both had been working fine before the upgrade and only one has the issue after hence my puzzlement. Both are running the same g-code so I have reduced the variables. I was going to re-seat the thermistor as my next step in trying to solve the issue, would you agree?

Posted : 20/11/2018 12:09 pm
Carl A
(@carl-a)
Estimable Member
Re: Thermal Runaway issue after upgrading Mk2 to Mk2.5

My heatsink ( hot end) is about half way below the plastic part. So how do I change that? I was getting leaks above it so secured the ribbed part tighter into the hot end block. Maybe that is why I have been having problems bringing temps up to the settings. Also some other problems but having plastic ooz out where the ribbed part screws into the hot end is not a good thing either. Help!!

Posted : 13/12/2018 12:11 am
Carl A
(@carl-a)
Estimable Member
Re: Thermal Runaway issue after upgrading Mk2 to Mk2.5

Note, did not make clear that the hot end and the ribbed part are as snug as possible so do not see how I can raise the hot end any ferther.

Posted : 13/12/2018 12:12 am
Carl A
(@carl-a)
Estimable Member
Temperature drift after upgrading Mk2 to Mk2.5

Joan, My temp is set to 215 for the first layer and it is stable at that temp. Then when the printer goes to next and above layers the tem, which is set to 210 for PLA will drop to 200 +- 2 degrees. A tech at Prusa said drop the fan speed but that seems to be a fix that should not be necessary

My hot end block is setting so that the mid point of hot end block is even with bottom of plastic part holding PINDA - about 1mm gap between the top of the block and the bottom of heat sink

I just looked at the picture above and read what you said and the bottom of the heat sink is correct on mine so I guess that is OK. What I wonder about is where the hot end is placed. Up tight with the heat sink (1mm gap) or with a wider gap. A wider gap would lower the hot end and may resolve the problem I am having with reaching the set temperature without adjusting the fan to a lower speed as directed by the Tech. It would move the hot end to a different position in the air stream of the hot end fan.

Appreciate your advice.

Posted : 13/12/2018 5:33 am
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