Nozzle Temperature drops mid print

  • Ive been having problems with a certain print getting to the second layer and for some reason just cant maintain setpoint. In my case the nozzle temperature is 205 for all layers, and it happily prints layer one without any problem. The temperature trend looks normal with a slight dither. Layer two starts, and and the temperature drops (not the setpoint, but the actual) to around 195 and flatlines (no dither) I lowered the speed to 20% to make sure it wasnt just running too fast, but even super slow it cant keep up.

    I dont see anything in the G-code out of place where the second layer starts, so im flummoxed. I am slicing with Cura 4.2.1
    It seems ive had this problem before, and I at the time I think I just resliced from scratch using a previous known good print, and the problem stopped. I think 😞

    It just somehow seems to be print dependent, though I cant fathom any reason why.

    Any thoughts appreciated....Henry

  • @HenryDara The usual cause of that is the part cooling fan coming on and blowing cold air over the nozzle. It's normal for slicers to turn off the part cooling fan for the first n layers. Check the gcode to see if there is an M106 which coincides with the point where the temperature drops.
    If that is the case, then your options are to fit a silicone sock or redesign the fan ducting. If you fit a silicone sock, you should retune the heater PID.

  • @deckingman That makes perfect sense. The times it worked best are the times I was printing Ultrafuse which doesnt run the fan at all. Son of a gun. 🙂

    Thank you for your help!!

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