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Temperature fluctuations... is this normal?

I'm not ready to "ask for help" yet. I recently changed from whatever stock f/w came on my Sidewinder X1 to Marlin 2.0.8.1. I ran the PID tune and printed. No problems, in particular (prints aren't the greatest yet), but wondering if the attached chart looks normal. Printing started at the green arrow.

I can't say I recall seeing fluctuations like this before. Nothing that caught my eye anyway.

Thanks.
Screenshot 2022-04-07 181842

update: it REALLY smoothed out shortly after the walls finished.
Screenshot 2022-04-07 182322

You may check the thermistor cables and also that the thermistor is well fixed to the heater block.

Whatever it was, it sure has calmed down:

Screenshot 2022-04-07 202236

The sharp drops and rises look like thermistor problems because it is physically impossible for the hot end temperature to change so quickly. You can see the realistic rise and fall rates at the start of the first graph when full power is supplied or it is turned completely off.

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May I ask what happened here? Bildschirmfoto vom 2022-04-08 17-34-12
Did you try things on the temperature control? There is a short drop of the target bed temperature to 0.
Also which Octoprint version are you using?

That was just me cancelling the print (just as it was about to start) and restarting shortly after. I noticed the filament was coiled improperly and would cause a problem.

Octoprint 1.7.3

Do these variations happen all the time, or only while the printer is autolevelling ?
Your firmware could have PROBING_HEATERS_OFF activated ; this option gives such variations while probing.

I don't have any sort of auto leveling.

I had similar erratic temps under 2 different conditions.

  1. I had to replace the heater and with a 24v system I inadvertently replaced it with a 12v heater. The extra high heat in the heater caused temps to overshoot the settings. That was fixed by installing a proper heater and using thermal compound inside the heat block so there was 100% contact and thermal transfer between the heater and the block.

  2. With the default installation the thermister was only inserted into the block with the potential for it to move slightly and not make contact 100% of the time. This was also fixed by adding thermal compound so there was no air and no loss of contact between the thermister and the block.

Since I made both those changes my extruder temps have remained rock solid, usually within 1 to 1.5 degrees of the setting