What should i do with this horible temperature variation?

3D Printing
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What should i do with this horible temperature variation? If anybody knows please tell me

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thermal compound on sensor and heater - check cable, maybe replace sensor.

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after the same problem i used some thin teflon/ptfe tubing to “clamp” it in so it will get pushed against the metal of the hotend - the crimping/solder of the thermocouple could also be loose

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Your nozzle can’t be changing temperature that fast. If the thermistor is loose and a fan is blowing on it, that can show wild swings. Make sure it’s secured in the heat block, and make sure a fan isn’t blowing on the nozzle.

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Thanks for sugestions, tomorow after finishes printing (bad quality and spongy) i will check everything

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@Petruse_Mihai what board is in that model? Looks similar to the wanhao case and one of their boards needed better grounding of a few pins to fix a similar issue.

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checklist : 1 thermistor secure . 2 pid calibration done with fan on 3 heater block covered with a insulation ( not that necessary ) 4 heater wattage not too low/loose in the block

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@Geoffrey_Forest you can put thermal paste on the thermistor, inside the block? I didn’t think about that but won’t the paste dry out quickly at high temps? Or do you use a high temp paste? I only have PC thermal paste laying around and I don’t think it’s rated for 200c temps.

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I did open it because it sounded very bad, like it is going to fall appart, and the heater and the screw from termistor was loose. Ps. is cr-10

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Now the temperature is stady. Thank you all for good advice

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@Kevin_Danger_Powers you’re right! It would probably dry out and get hard (it would still work, just might be impossible to remove). I was thinking about the thermistor in my heated bed, I used thermal paste there. My hotend has a screw-in type of thermistor, so that keeps it in good contact. I’ll edit my comment above.

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@Petruse_Mihai if it is now steady - there might be a broken cable/contact, so resistance is changing…

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The temperature is the one that it should be, it works fine. Ps. The screw from termistor was loos to but i did not see it because it was wraped

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I set for 215,PLA, and it stay there not fluctuating

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There is a known issue with one of the capacitors on one of Creality boards that causes temperature instability of hot end

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Why did your firmware not cancel the print when this happened? This is a huge fire safety hazard.

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Last time I saw apparent temperature swings like that, it turned out I had the wrong thermistor table selected, and was operating above the range of useful values included in it (the table in question was obviously only intended to be used for platform heaters). @Kevin_Lease 's explanation seems more likely in this case, though.

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Make sure to check your wiring to ensure continuous a resistance as the cable is moved along with the print head. If the wire resistance changes with movement this could be why you’re seeing temperature fluctuations.

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the real problem was here, bad connection
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