The printer worked normally, until during a 14 hrs print, it shutdown midway with the warning of “Heater extruder not heating at expected rate”. I found the hotend fan blowing on the heatblock causing it struggle to keep temp up, so I sealed the leakage, and thought it’s done. Then I try to reprint, twice, both failed with the same reason. But I dont see any temp problem in the log for the later two case.
Wasted 800g ASA, really scratching my head for the cause, any help wanted!
Interesting that your extruder has a single 1-star review from three months ago that mentions this specific issue. The reviewer hypothesizes that the heater is simply too weak. Try slowing your print down and see if that helps.
The resolution in the graph does not allow judging it.
Noteworthy is the area around 21:00 where you suddenly have high PWM values. “Something” happened here forcing Klipper to push more power into it.
Klipper is not able to reach a stable temperature.
Some things you could try:
Use a stronger heating cartridge. If you only have these 40W variants, you will not have much fun at these temperatures
Insulate your hotend with a silicone sock
Perform PID tuning at this temperature with fan on. Most likely in your current configuration Klipper will fail to perform the PID tuning as the disturbances are too large for the heaters power
Possible but not recommended: desensitize the settings via verify_heater
hotend comes with a silicone sock.
I have done PID tuning with 100% fan at 15C room temp.
I already set verify_heater like this before log 9:
[verify_heater extruder]
max_error: 120
check_gain_time: 20
hysteresis: 5
heating_gain: 2
Should I try to increase hysteresis even more?
Rather than the heating power, the small thermal mass might be the cause of fluctuation, which makes PID control overshoot. I have seem someone discussing improve PID algorithm by utilizing trapezoidal rule on github before.
I upgraded heating cartridge to 80w, recalibrated PID, reprint, and failed again. klippy (10).zip (1.9 MB)
The temp drop is filament change. printer.cfg (14.4 KB)
@woodencliff can you try to reproduce the error and immediately after it issue the M112 command?
This will output additional debug information. Maybe it is good for nothing, maybe it helps. Absolutely possible that I’m dramatically missing something obvious, but currently I’m dumbfounded.
Your config shows non-standard values in the extruder section:
pwm_cycle_time: 0.01
smooth_time: 0.1
Where are those values from?
Maybe with this small smooth time there are some artefacts steadily increasing the max_error parameter of the verify_heater check.
See the description of smooth_time:
A time value (in seconds) over which temperature measurements will
be smoothed to reduce the impact of measurement noise.
Even the small pwm_cycle_time might cause some unnecessary peaks.
If you can reproduce the error quite easily stick to the defaults (comment out those two lines) and verify it after a restart.
Excellent observation @LifeOfBrian
Personally, I would think that indeed such parameters could be the cause but IMO they would cause unstable temperature readings and in my view the readings are OK.
What do you think?
In any case: @woodencliff comment out both parameters to force their default values and try again please.
I bet on that horse…
If I’m not wrong the standard smooth time averages/smooths the temperature readings and hides unwanted peaks.
Like on Digital filters with averaging or reduced FFTs.
With this short time those peaks can come out of the dark and make trouble.
And doesn’t klippy.log logs the stats only every second maybe hiding stuff inbetween as well?