Temp woes continue ...



  • Just installed a PT1000 temp sensor on my CR-10S Maestro.

    Ran a PID Tune and all ran well. I ran: M303 H1 S250 then saved with M500.

    Resulting in this config-override.g

    ; Heater model parameters
    M307 H0 A90.0 C700.0 D10.0 S1.00 V0.0 B0
    M307 H1 A267.5 C148.7 D3.6 S1.00 V12.1 B0
    M307 H2 A340.0 C140.0 D5.5 S1.00 V0.0 B0
    G10 L2 P1 X0.00 Y0.00 Z0.00
    G10 L2 P2 X0.00 Y0.00 Z0.00
    G10 L2 P3 X0.00 Y0.00 Z0.00
    G10 L2 P4 X0.00 Y0.00 Z0.00
    G10 L2 P5 X0.00 Y0.00 Z0.00
    G10 L2 P6 X0.00 Y0.00 Z0.00
    G10 L2 P7 X0.00 Y0.00 Z0.00
    G10 L2 P8 X0.00 Y0.00 Z0.00
    G10 L2 P9 X0.00 Y0.00 Z0.00

    But when I went to extrude the feed was very sluggish like the temp was low. I'm extruding FlexSolid which runs from 240-250°C normally. Being a flex I can't run it hard, but it was barely coming out of the nozzle.

    Pulled it and cleaned nozzle thoroughly with eSun cleaning filament, did several cold pulls and used a .4 needle to check my hardened nozzle was clear. The cleaning filament seemed sluggish too, I've used it a number of times. At 250 it runs easily, not this time.

    Suspecting PT1000 sensor was reading low (but measured OK) I pulled it back a bit in the E3D copper plated block and inserted a K thermocouple reading it on my bench DVM. It's fully inside and in good contact.

    When Duet reads 255°C the thermocouple reads 230°C

    Here's the temp chart (turned heater off):
    0_1551891946926_Temp Chart.JPG

    Here's the config.g heater section:

    ; Heaters
    M307 H0 B0 S1.00 ; Disable bang-bang mode for the bed heater and set PWM limit
    M305 P0 T100000 B4388 C7.060000e-8 R2200 ; Set thermistor + ADC parameters for heater 0
    M143 H0 S120 ; Set temperature limit for heater 0 to 120C
    M305 P1 X501 R2200 ; Set thermistor + ADC parameters for heater 1
    M143 H1 S305 ; Set temperature limit for heater 1 to 305C

    What could be wrong here?



  • @puterpro said in Temp woes continue ...:

    M305 P1 X501 R2200

    How did you determine your R value?

    Are you using any extenders on the PT1000 wires?

    The graph looks pretty wavy. Try rerunning the PID tuning at a lower temp. Say 220c.



  • before heatup is the temperature of the pt1000 the same as your bed?


  • administrators

    @phaedrux said in Temp woes continue ...:

    The graph looks pretty wavy. Try rerunning the PID tuning at a lower temp. Say 220c.

    Alternatively, don't re-tune but try increasing the D parameter in the M307 H1 command by about 30%.



  • @Phaedrux - Thanks for the quick reply! The R value was put in originally by RRF Config Tool, it's a Maestro so it has a 2200Ω resistor onboard (unlike the other Duets which have 4700Ω), so I just left it in when I changed the line for the PT1000.

    Extenders - used the original extensions.

    Re-run at lower - well, I intend to do a lot of hotter stuff so I wanted it to be tuned a bit north of normal.

    However - re-ran at 240° , To my amazement and delight the stupid damn thing straightened out, nearly flat now. Duh. Should have tried before posting (hindsight and all, LOL).

    What threw me was the large temp difference I was observing / measuring. I understood the PID tune to adjust ramp up, overshoot and dwell, not change the total (or "top") temp. Am I misunderstanding this?

    @dc42 - Thx, as always! Well, after re-tune it ended at M307 H1 A425.6 C235.0 D5.3 S1.00 V12.2 B0
    Completely different C & D values, with D way up . Smooth as silk now. Who knows what evil was at work I think sometimes these machines screw with us just for fun (insert machiney chuckle).

    Thanks guys! Running it now and all appears well (well, minor fan issue but separate post going up)
    Cheers!


 

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