Hotend doesn't maintain temperature
My ~1 month old MK3S doesn't seem to be able to maintain temperature properly. At first I had what appeared to be a mid-print clog about half way through a ~6 hour print. But now it slowly stop extruding filament a minute or so into any new print jobs. I've done the usual stuff to clear the nozzle and tried a couple different spools of filament. They didn't help.
I pre-heated to 210 degrees, and manually extruded filament slowly while checking the temperature of the hot end with a laser heat sensor. After about a minute, the filament wouldn't manually extrude and the external temperature of the heat block had dropped from ~190 degrees to ~140 degrees. The LCD display still claimed that the temperature was 210 degrees.
I tried running a test print while checking the temperature of the hot end, and observed similar results. When the filament stops extruding, it's because the temperature of the hot end has gone down by 50 or so degrees. Manually increasing the temperature helps in the short term, but the hot end just cools off again after a minute or two and the filament stops extruding, but the LCD still says the temperature hasn't changed.
Has anyone seen this before? I couldn't find any forum posts that sounded like the same issue. Is this maybe a thermistor problem?
Re: Hotend doesn't maintain temperature
8.1 PID tuning for Hotend (Optional)
If you are experiencing wide swings in temperatures of your nozzle (e.g +/- 5 C°), you shall do PID tuning on your printer. If you are experiencing major temperature fluctuations higher than that, first check that your hotend thermistor is properly seated in the heater block and plugged into your EINSY board.
You can find this feature in LCD Menu - Calibration - PID calibration. In this menu, you have the option to choose the temperature for which the PID will be run. Set the temperature with which you print the most as it will tune itself ideally for the selected temperature. However, the general stability will improve for all temperatures (PLA/ABS/PETG). After that, the nozzle will heat up to the set temperature in 5 cycles. During the cycles it is mastering
the amount of power needed to reach the temperature and maintain it.
Do not touch the nozzle during this process until the process is fully finished as it will reach high temperatures!
Be aware that PID tuning is not a solution to all of the temperature fluctuation issues. Always make sure that your printer is located in a room with stable ambient temperatures; more information can be found at Thermal Runaway and Temperature Drops at help.prusa3d.com.