Assistance with hotend deadtime/faulting under heavy load?



  • I am experiencing heater faults when rapidly printing ABS with a 1.2mm nozzle on a Slice Mosquito Magnum hot end. I am over-setting my temp to 280c to compensate, but it is struggling to sustain that temp while melting so much filament.. it can sustain 270-275c, but it lays down smoother at a bit higher temp. So, for this use case, it appears I may be forced to leave the heater enabled the entire time - or slow everything down (boo!) so it can sustain 280c.

    How have others combated against this? I can increase deadtime, but what if it never quite stabilizes at 280c?



  • Try logging periodically with M573 to see what PWM the heater is running at under full load. This should give you an idea of whether you can tune the control values up.

    For example, if it's constantly running a PWM of 1 (full power) then you are just running too fast for your heater power. At that point your decisions will be either print slower, substitute a more powerful heater, tune the voltage up as high as possible if you have adjustable output, or cut wasted heat by insulating better or something like that.

    If it's running a lower PWM value, say 80-90%, or it oscillates around, then you should still be able to tune it up, maybe by aggressively increasing the gain? I prefer just using overpowered heaters, although there's some safety things to consider here.



  • @nhof this helps.. thanks!



  • Excellent advice from @nhof.
    I could add use a silicone "sock" if you aren't already doing so. I guess you will have discovered already that large nozzles put down a lot of plastic which takes a lot of cooling to prevent parts from sagging. That aggressive air flow can cool the nozzle if it isn't well directed (and it's almost impossible to eliminate cooling air being deflected onto the nozzle from the part being printed of the build platform).



  • @deckingman we learned a lot from a big print we just completed.. but I want to go bigger this weekend, however I do believe we are near the maximum a 50w heater can go..

    Check out the photos we just posted! https://forum.duet3d.com/topic/18485/oozebot-ele-gant/38



  • @oozeBot said in Assistance with hotend deadtime/faulting under heavy load?:

    ..............I do believe we are near the maximum a 50w heater can go..

    That's more then likely. I'm using 80 watts on my experimental 6 input hot end - but the melt/mixing chamber is probably a lot larger volume than a volcano.


  • Moderator

    @oozeBot said in Assistance with hotend deadtime/faulting under heavy load?:

    however I do believe we are near the maximum a 50w heater can go..

    I'm curious to see what results you'd get for max volumetric flow rate using this test.

    https://duet3d.dozuki.com/Guide/Ender+3+Pro+and+Duet+Maestro+Guide+Part+4:+Calibration/40#s177


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