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Extruder temperature not stable,changing in a range about 14 °C

raymondraymond
in Extruder & Bed
Hope somebody could help with this. Firmware version is 0.92.9; Power is 24v ;extruder heater 24v 40w. I have tried different Temperature manager,different Dead time lag from 2 sencond to 9 second,and different Max PWM value,and 3 different heater from different supplier too,but I got no luck,the temperature changed from about 5 °C lower to 8°C then the target temperature.

Comments

  • RepetierRepetier
    So you mean it swings with a range of 14°C.

    1. Use PID and autotune it with M303
    2. You might reduce max pwm. I think you are so overpowered that a small push causes a big overshoot.
    3. Test on target temperature not on low temperatures. The result differs since you need much less power in lower temp. range.
  • raymondraymond
    Thanks for the advice. I reduce the max pwm to 80,run M303 and the autotune finished . 00:35:32.802 : Info:PID Autotune start 00:37:29.424 : bias: 73 d: 73 min: 147.37 max: 157.95 00:37:59.859 : bias: 68 d: 68 min: 146.98 max: 153.69 00:38:29.851 : bias: 67 d: 67 min: 147.17 max: 153.24 00:38:29.851 : Ku: 14.06 Tu: 29.98 00:38:29.851 : Classic PID 00:38:29.851 : Kp: 8.44 00:38:29.851 : Ki: 0.56 00:38:29.851 : Kd: 31.61 00:38:59.622 : bias: 66 d: 66 min: 147.27 max: 153.18 00:38:59.622 : Ku: 14.21 Tu: 29.77 00:38:59.622 : Classic PID 00:38:59.622 : Kp: 8.53 00:38:59.622 : Ki: 0.57 00:38:59.622 : Kd: 31.73 00:39:29.460 : bias: 66 d: 66 min: 147.27 max: 153.01 00:39:29.460 : Ku: 14.63 Tu: 29.77 00:39:29.460 : Classic PID 00:39:29.460 : Kp: 8.78 00:39:29.460 : Ki: 0.59 00:39:29.460 : Kd: 32.67 00:39:29.460 : Info:PID Autotune finished ! Place the Kp, Ki and Kd constants in the Configuration.h or EEPROM Then I restarted the printer,set the target temperature to 180 °C,but it still swings from 177°C to 186 °C
  • raymondraymond
    i reduced max pwm to 115 and it's now only 1 °C higher then target temperature,but it's about 4 °C lower then the target temperature before it rises again,any advice for that?
  • RepetierRepetier
    Can you still go up to 200°C? Sounds a bit a sit has problems getting over 180 with that max pwm making it hard to control. Also note that the first swing always goes too high and it should get better with each following swing. But I do not optimize it so often that I can say this parameter is responsible for it. I value has to converge to required PWM so you might need to reduce it a bit to make it converge more stable.

  • raymondraymond
    I get a perfect result with dead time control now,Max PWM value 125,and Dead time lag 9. now it only swings 2 °C lower and 1 °C higher.
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