Heating error on heater 1



  • I keep getting the following error, which spoils a print.

    Error: heating fault on heater 1, temperature rising much more slowly than the expected 0.3°C/sec
    Warning: Tool 0 was not driven because its heater temperatures were not high enough or it has a heater fault

    This happens when the cooling fan speed is increased, causing the nozzle temperature to drop dramatically, it then take a long time to recover or it faults.

    How can I resolve this?
    I am using firmware 1.15c
    WiFi Server 1.02
    Web Interface 1.12



  • What hotend are you using?
    Have you used M303 for PID tuning?



  • I had this problem, too, until I lowered the fan speed to 75%.


  • administrators

    Once the target temperature has been reached, the rate of temperature rise should not matter. All that should matter is that the temperature remains within 10C of the target.

    Do you have an extruder temperature change at the same time that the layer fan speed is increased? How much does the temperature drop when the fan speed is increased?



  • Using PID tuning.
    Perhaps I need to lower the fan speed but I would prefer the heating system to recover the set temperature more quickly.


  • administrators

    Yes it should recover quickly, that is one of the things I changed in the C revision of 1.15. I have this down as an issue to investigate for the 1.16 firmware version.



  • I was actually just coming here to post on this. Many things are very polished on the Duet Wifi's firmware but the temperature system has given me the most problems.

    I can usually do a print without a temperature fault on heater 1, even with my massively oversized fan blowing at full speed on my heater block. (I have a 12V fan and 24V system. It turns out you can't regulate speed through a buck converter. I'll be gettting a new fan soon). Basically, I believe my autotuned with M303 hot end to be pretty well tuned.

    However, I can fault the heater about 80% of the time by letting the hot end cool half way back to room temperature and then re-enabling the hot end to go back to temp.

    Is it possible to relax these checks with M codes? I appreciate the intent but this shouldn't happen so often that I created a reset heaters gcode!

    On a similar note, I tried to see if I could do better with manual PID tuning but it's impossible to tune a PID loop if the heater faults every time you exceed 10 degrees of the setpoint!



  • @dc42:

    Yes it should recover quickly, that is one of the things I changed in the C revision of 1.15. I have this down as an issue to investigate for the 1.16 firmware version.

    Mine is taking too long to recover, even with the fan set to 50%.

    Does it make any difference with tuning at 0.45 or 0.2 as an example to the way the heater will recover?

    Do I need to re tune using different parameters?


  • administrators

    The PWM factor you use when tuning should not make much difference to the heater model it deduces, or to how fast the temperature recovers.

    Don't forget that you can revert to manual PWM parameters if you think that temperature control worked better for you in firmware versions 1.14 and earlier. Leave the M307 command in config.g but put a M301 command after it with your chosen PWM parameters.



  • Another thing to try, turn on the fan to 100% and then run a M303.



  • At this point, 2/3 of my prints are failing because of hot end heater errors. I know my heater is over powered and autotune doesn't handle this situation all that well. However, I couldn't even manually tune because the heaters fault out while trying to tune.

    Currently, it faults out when heating up, it faults out when the fan kicks in, it even can fault out mid print.

    I get that the firmware is setup for maximum safety but is there a user configurable way to widen the safety margin or disable it until the tuning tools get to where they can handle my setup?

    (In case I come across as too complainy here, I do appreciate the development effort!)



  • @LeonMF:

    At this point, 2/3 of my prints are failing because of hot end heater errors. I know my heater is over powered and autotune doesn't handle this situation all that well. However, I couldn't even manually tune because the heaters fault out while trying to tune.

    Currently, it faults out when heating up, it faults out when the fan kicks in, it even can fault out mid print.

    I get that the firmware is setup for maximum safety but is there a user configurable way to widen the safety margin or disable it until the tuning tools get to where they can handle my setup?

    (In case I come across as too complainy here, I do appreciate the development effort!)

    Can you revert to a version of RRF before the heating changes were made, so you can use the legacy PID?


  • administrators

    @LeonMF:

    At this point, 2/3 of my prints are failing because of hot end heater errors. I know my heater is over powered and autotune doesn't handle this situation all that well. However, I couldn't even manually tune because the heaters fault out while trying to tune.

    Currently, it faults out when heating up, it faults out when the fan kicks in, it even can fault out mid print.

    I get that the firmware is setup for maximum safety but is there a user configurable way to widen the safety margin or disable it until the tuning tools get to where they can handle my setup?

    (In case I come across as too complainy here, I do appreciate the development effort!)

    Leon, if your heater faults when heating up, that should be easy to fix by increasing the dead time and/or reducing the gain in the M307 parameters.

    To auto tune an over-powerful heater, you currently need to use a low P parameter in the M303 command, perhaps as low as 0.1.

    If it faults when the print cooling fan comes on, that means the temperature has dropped by more than 10C. I am considering making this figure configurable in a future firmware version; but isn't a temperature drop of that size going to cause extrusion problems anyway?

    HTH David



  • The problem is that the last 3 prints have failed due to heater faults whether the fan was on or not! Currently, my temperature hovers right at temperature but then there will be a quick excursion that immediately return to temperature. Honestly, I'm not sure why it has gone downhill so badly. I'm going to double check my wiring and try retuning tonight.

    There are three things I'd like to see, which would dramatically help people like me:
    1. User configurable temperature band.
    2. User configurable time out of band. I will make the argument that a brief excursion should not fault the heater. A web console warning wouldn't be a bad idea, though.
    3. When the heater faults, kill the print. It's not doing me any good running if it isn't extruding.

    Thanks!


  • administrators

    A brief temperature excursion does not fault the heater. The error has to be maintained for more than 5 seconds before a fault is registered.



  • Interesting… I've never been able to catch it. I'll investigate and report back if I get a better understanding.


  • administrators

    If you do manage to catch it, p!ease report the text of the initial heater fault message if you can.



  • The log says "Temperature Excursion too large".

    It turns out that this problem, at least was due to a noisy thermistor. Probably from me zip tying the thermistor to the heater cartridge without enough slack for strain relief. Thanks for all your help!

    I'll know later tonight if this fixed it.



  • I've also had a few issues with this. My heater is over-powered, but it was intentional in the hope that I could print fast and be able to reach higher temperatures (300C). The auto-tune worked brilliantly and it prints with no errors so long as the print temperature is below 220. If I increase it to 260 (or higher), it will fault mid print usually with the temperature going too high.

    At higher temperatures, I think the thermal inertia is such that an excursion can last more than 5 sec. This usually happens on fiddly bits where the material flow reduces.

    If it were possible to relax the thermal fault detection (perhaps with a strongly worded warning about fire, death & destruction?) I think it might help this.

    On the fire front, I have a DIY thermal fuse. A short length of solder mounted a couple of cm above the heater. Even at 300C, it does not melt the solder - but either a flame or a temperature above 400 will. It required a bit of experimentation to get the separation right - but it seems to work. If the solder link breaks, it kills the mains via a SSR.

    I suspect that an off the shelf thermal fuse with poor thermal contact to the heater would do just as well.

    Si




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