Heater faults with numerous different heaters and thermistors

  • I've been building a HEVO, using a DuetWifi as the control board, on and off for some time now and am so close I can taste it. However I am getting heater faults after a few minutes of printing no matter what I do. I'm running a 24v PSU and have tried all manner of heater cartridges and thermisters from god awful cheap Chinese to expensive versions. Always using autotune to get the correct settings. My current setup is uses a 40w heater cartridge, E3d block in a E3D Thermistor Cartridge. I've checked and double checked wiring and all connections are good, i've also tried numerous different types of connectors with no luck.

    I'm now at my wits end - either i have something set wrong or there is an issue with my DuetWifi

    Haven't quite figured out how to add picture, here are my main configs

    Firmware Name: RepRapFirmware for Duet 2 WiFi/Ethernet
    Firmware Electronics: Duet WiFi 1.02 or later
    Firmware Version: 2.0(RTOS) (2018-06-05b3)
    WiFi Server Version: 1.21
    Web Interface Version: 1.22.3

    Any pointers would be greatly appreciated - thanks in advance

    ; This is a system-generated file - do not edit
    ; Heater model parameters
    M307 H0 A93.7 C333.1 D0.2 S1.00 V24.5 B0
    M307 H1 A322.4 C188.4 D4.3 S0.75 V24.4 B0
    M307 H2 A340.0 C140.0 D5.5 S1.00 V0.0 B0
    M307 H3 A340.0 C140.0 D5.5 S1.00 V0.0 B0
    M307 H4 A340.0 C140.0 D5.5 S1.00 V0.0 B0
    M307 H5 A340.0 C140.0 D5.5 S1.00 V0.0 B0
    M307 H6 A340.0 C140.0 D5.5 S1.00 V0.0 B0
    M307 H7 A340.0 C140.0 D5.5 S1.00 V0.0 B0

    ; General preferences
    M667 S1

    ; Network
    M550 P<--WIP-->
    M551 xxxxxx
    M552 S1
    M587 S"xxx" P"xxx"
    M586 P0 S1
    M586 P1 S0
    M586 P2 S0

    ; Drives
    M569 P0 S0
    M569 P1 S0
    M569 P2 S0
    M569 P3 S1
    M350 X16 Y16 Z16 E16 I0
    M92 X80 Y80 Z400 E420
    M566 X900 Y900 Z24 E100
    M203 X6000 Y6000 Z400 E1000
    M201 X500 Y500 Z100 E250
    M906 X800 Y800 Z800 E800 I30
    M84 S30

    ; Axis Limits
    M208 X0 Y0 Z0 S1
    M208 X290 Y270 Z300 S0

    ; Endstops
    M574 X1 S1
    M574 Y1 S0

    ; Z-Probe
    ; Precision Piezo Orion
    M574 Z1 S2
    M558 P8 I1 R0.8 F600 X0 Y0 Z1 H5 T6000
    G31 X0 Y0 Z-0.05 P100
    M557 X20:290 Y20:270 S20

    ; Heaters
    M307 H0 B0 S1.00
    M305 P0 T100000 B4725 C0 R4700
    M143 H0 S120
    M305 P1 T100000 B4725 C7.060000e-8 R4700
    M143 H1 S280

    ; Fans
    ;Fan 0-Bed, 1-Hotend
    M106 P0 H-1
    M106 P1 T45 H1

    ; Tools
    M563 P0 D0 H1
    G10 P0 X0 Y0 Z0
    G10 P0 R0 S0

    ; Automatic power saving
    M911 S10 R11 P"M913 X0 Y0 G91 M83 G1 Z3 E-5 F1000"

    ; Custom settings are not configured

    ; Miscellaneous

  • @foden The most common cause of heater faults occurring a few minutes into a print is the part cooling fan coming on and blowing cold air over the nozzle. Try turning off or disabling the fan temporarily to see if that fixes it.

  • administrators

    As well as making sure that the part cooling fan blows on the print not on the heater block, you can put a silicone sock over the heater block if it doesn't already have one. You will need to re-tune the heater.

  • @deckingman Thanks deckingman, had'nt thought of that and it does fit the pattern as it's off initially., Will test out later today

  • @dc42 Thanks dc42, I forgot to mention it has a silicon sock on the block. I will try deckinman's idea of turning off the fan. Hopefully that's it and i just need to work out a better cooling fan assembly

  • @foden screenshots are here https://imgur.com/a/UDpWWIV
    looking at the temp chart its pretty stable until it fails, so could indeed be the fan kicking in. Have included a shot of what the fan looks like, it should blow air onto the part but could also be bouncing back onto the hot end

  • administrators

    Unless you have configured your slicer for the fan to turn on later, the print cooling fan normally turns on at the start of the second layer. But it looks like you printed 10 layers before the problem occurred.

  • @foden It's fairly common for the air flow to be directed back off of the build plate or the printed part itself, onto the nozzle. A silicon sock usually helps though. But until you test with the fan off, all else is just speculation.

    If turning the fan off cures the problem, then simplest thing to do might be just to limit the fan speed to (say) 50% using the X parameter in M106 https://duet3d.dozuki.com/Wiki/GCode#Section_M106_Fan_On

    Edit. That's good timing - DC42 and I both posted at exactly the same time.

  • @dc42 Currently cooling settings are

    1 0%
    3 50%
    5 75%
    7 100%

    so by layer 10 it may be at the tipping point temp wise

  • @deckingman Hopefully that's it and I can start to grow my hair back ;o) will no later today

  • Not conclusive, as I haven't had chance to do a long test print. However, after 15 mins with the fan on 50% the printer is 'as happy as Larry' - and so am I. Hopefully I will have chance to do a full test tomorrow evening. Feel a little dumb for not seeing the correlation between cooling fan and the issue...facepalm 🖐

    Regardless THANK YOU both VERY much indeed for pointing me in the right direction!!!

    Hopefully will be able to update fully late tomorrow

  • Now it's conclusive - 100% fan back-blow was the issue. Anything above 8% and it would create a heater fault. Have to look to a different fan duct as the semi-circular one I'm using seems to make it worse. Without a fan at all you eventually get a large mass of filament and no print :o(

    Thank you both so much for your pointers. I can now move on to the next hurdle, what ever that will be ;o)

    OK, so where were the plans for the better fan.....

    Thanks guys!

  • @foden Ahhh Nutz!

    Not completely solved, even on 5% fan i get heater failure after about 15mins. Just ran another text with no fan duct, so air goes straight onto the bed behind the hotend. Fan was at 5% and i didn't use any filament. Heater fault at 1 hr 1 min 14 seconds, will repeat with the fan off and see what happens

  • administrators

    Does the temperature graph show a gradual deviation from the set temperature, or a sudden change?

  • @dc42 Hi dc42, it was a sudden change - currnelty into the test, 52 mins, with no fan or filament

  • @foden This is what it looks like so far https://imgur.com/a/ycVP0K4. When the fan is on there is a very slight tremor/wave in the hot end temp line

  • @foden Now past where it failed last time, will leave it until the end or it fails 32% to go yet

    The hot end I'm using has a e3d v6 block and thermistor, with the thermistor at the back nearest the fan. I may tril rotating the unit 180o to see what that does

  • @foden completed print run without issue

  • Silicone sock?

  • @phaedrux Yes, there's a silicone sock on the heater block

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