Anycubic I3 Mega - temperature drops while printing



I was referred to this forum with my problem. Installation and connection of Octoprint (Version 1.3.6) to Anycubic I3 Mega (Version 3, 8bit Board, frimware 1.1.0) worked w/o problems. Also uploading of gcode files and start printing is ok. After a while (> 20 minutes) the temperature of extruder and bed drops suddenly. Console just shows that cold extrusion was prevented, but I guess this is just a reaction to the temperature drop. I never had such problems while printing from SD. With octoprint all attempts failed for the same reason. I have no idea what triggers the printer to reduce both temperatures.

I haven't found a similar issue in the issue list yet. Any idea or even advice how to solve this issue? As the printer works perfectly in stand-alone mode I do not see the problem related with the hardware. For me it seems something in Octoprint forces the printer lower the temparature.

Thanks in advance, Thomas


Hi Thomas, any news on your problem? Got the same issue here.

I tried a different power supply (2.5A) for the Pi but problem remains. I now go for a 3A PSU, ´cause I red about, that this may be a problem of non-consistent power. I will see...

Apx after 45 min, the temp of the hotend drops from 205°C to 170°C, goes up again nearly to 220°C followed by next drop below 180°C and again and again...
Rising temp from 205°C to, let´s say 215°C only gives effect, that drops are "only" down to 180°C but they still repeat.

Would be nice, if you git any news on this issue. I will report, if the new PSU gives an effect.



I'd be very surprised if the PSU for the Pi would make a difference here. It's the job of the printer or rather its firmware to maintain temperature, all OctoPrint does in that scenario is tell it "hey, please heat to X degrees, thanks". I'd rather look into the printer's PSU, its temperature calibration, PID tuning etc.


u´r right and that was I thought too but I was told, that an inconsistent power supply of the Pi can affect silly things.

By the way: connected to my Tevo Tarantula or BW printers, theres is no problem with this. They maintain temp for hours within +/- 1°C...

So this is worth a try if there are no more ideas... The i3 maintains temp as well, when printing from SD


So. I got the "original" Pi 3 PSU - no effect. Temp drops still remain after apx. 45 Min.

Made another testprint with same file but from SD Card (Pi turned of) - no problem. Temp stays stable around 205°C.

So this maybe a communication bug between Octoprint and Anycubic i3 mega...


I suggest you approach Anycubic about this then. Considering that temperature control is completely the responsibility of the firmware on the printer, if it's not able to hold temperature when a serial host is connected, but it is able to hold temperature when not, something's broken inside that firmware. Wouldn't be the only thing broken about it either.