E3D Thermistor Beta Setting?

  • When T3P3Tony replied to different question of mine; I noticed, when I visited the E3D wiki as result of his good advice, I noticed that the E3D thermistor Beta number is different from that generated by the config.g wizard. Up to this time, the E3D-V6 Hot-End and the cartridge thermistor (via auto-temp tuning) was working properly. The bed temp matter is a bit dicey, its workable, but something is screwy in it and it needs resolution at some future juncture.

    So I changed the Beta number for the E3D thermistor and re-ran auto-tune. Now, my hot-end errors out by not attaining any set target temperature. I fiddled around with the tuning for many hours the first time around and was able to finally to get it running properly. But now things are not working again. I suspect that my current matter is a procedural problem rather than being hardware or software. Perhaps something is stored that is interfering with the auto-tuning or something needs be commented out in the config.g file or something akin to that, before re-running auto-tune.

    The config.g file is written:

    ============== begin temp code chunk ===============
    ; hot-end 'E3D V6' heater
    ;M303 H1 P0.8 S240 ; send via g-console hot-end auto-tune cmd, when complt read: M307 H1, store: M500

    M301 H1 P22.2 I0.672 D66.7 ; hot-end PID determined by H1 AutoTune
    M307 H1 A473.6 C252.7 D4.3 S0.80 V11.4 B0 ; set Htr 1 (hot-end), g(A)in, Time Const, Dead Time, limit PWM=80%,
    ; CalVolts= 11.4, PID=0/Bang=1 (via M303 AutoTune)
    ; temp sensor for hotend ------------
    M305 P1 T100000 B4267 C0 R4700 ; Hot-End: Set thermistor (E3D says B=4267K, Semitec 104-GT2, not 4138K)
    ; + ADC parameters for heater 1, R4700 is series resistance
    M143 H1 S280 ; Set max temp limit for heater 1 to 280°C

    ============== end temp auto-tune chunk ===========

    thanks in advance


  • administrators

    The best values to use for temperatures around 200 to 250C are
    M305 P1 B4725 C7.060000e-8 as given at https://e3d-online.dozuki.com/Guide/V6+RepRap+Firmware+Configuration/26?lang=en. The B values quoted by thermistor manufacturers are usually for temperatures of 100C or less, so ok to use for a bed heater thermistor but not for a hot end.

  • @dc42

    Hah! Just what I was looking for. How do you know where to find these perls of info? I looked around, maybe I'm just getting too old, --all the young folks seem to know how to find it all?



  • administrators

    I started from the resistance vs temperature table and used an online calculator out what B and C values fitted the values at three temperatures of interest - I forget what I used, but something like 25C, 180C and 250C.