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Overshooting temps causing thermal runaway  

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Mike C
(@mike-c-2)
Eminent Member
Overshooting temps causing thermal runaway

Seems my temps are overshooting causing thermal runaway, what would cause this.

PLA

with ABS, did not error

Posted : 22/04/2017 1:58 am
Mike C
(@mike-c-2)
Eminent Member
Topic starter answered:
Re: Overshooting temps causing thermal runaway

When printing PLA, the fans kicks in and the temp will not get past 187, I lowered the fan speed to 152 and it would get to 198. Raise it back to 255 and the temps drop again. Any ideas?

Posted : 22/04/2017 3:21 am
OldCoder
(@oldcoder)
Trusted Member
Re: Overshooting temps causing thermal runaway

On my printer, this was caused by a failed print head fan, or failed wiring. I replaced the print head fan (small 30 mm square fan), and the problem went away.

Chris Shaker

Posted : 24/04/2017 2:28 am
PJR
 PJR
(@pjr)
Antient Member Moderator
Re: Overshooting temps causing thermal runaway

There's a couple of things you can try:

Change the fan nozzle: http://www.thingiverse.com/thing:1947953/#files
Wrap the heater block in kapton tape
Install the E3D sock

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…

Posted : 24/04/2017 3:54 pm
Mike C
(@mike-c-2)
Eminent Member
Topic starter answered:
Re: Overshooting temps causing thermal runaway

Thanks for the responses, I will recheck my wiring again and try a different fan shroud.

addditional info

when printing with PLA @ 200 degrees with no fan for the first layer, then turning on the fan on the second layer the temp would drop by at least 10 degrees and go into Thermal Runaway. If I manually turn the extruder on to 200 degrees, then turn on the fan the temps are stable. I have also tried while moving the motors all around and with a heated bed, manually there is no change.

Posted : 25/04/2017 12:14 am
Mike C
(@mike-c-2)
Eminent Member
Topic starter answered:
Re: Overshooting temps causing thermal runaway

Working with support we found that if I took the extruder cover off temps were right where they were supposed to be, with the cover on the temps would drop. I finally went back to the original MK2 extruder cover and everything is working correctly now.

Posted : 27/04/2017 6:21 am
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