Print failure due to heater inconsistency

Question

After encountering an issue where the original heater cartridge (~40 W) for my generic MK6 hotend was unable to reach/maintain stable temperature at ~260 °C (for PETG) I replaced it with a higher wattage heater (60 W). The new heater heats up faster and can maintain temperature, but I noticed that if I try to print too fast it will become unstable and the printer stops with a heater error, even with a lower temperature of 250 °C. This can be seen in the temperature plot below.

I have performed PID tuning (see the nicely flat spots on the temperature plot), so I don't think that's the issue. The thermistor is well-secured to the block.

I am using a BTT SKR Pico V1.0 control board with Klipper over UART to a Raspberry Pi A3. Does anyone have experience with an issue like this? Could it be that the SKR Pico is not supplying sufficient power while also running the motors and heated bed?

Answer 1

This is very similar to what I recently experienced in the question Diagnosing sudden problem with hotend temperature, where the root cause seems to have been a bad thermistor - internal conductors probably broken in a way that they intermittently make reduced contact during toolhead motion. But I didn't have a problem while heating like your graph shows, only during motion, so it's also plausible that the wiring to the heater is bad. Since these aren't expensive components it might make sense to just replace the thermistor, heater cartridge, and any asssociated wiring if you don't want to spend time fighting with the problem.