M303 PID autotune

[lele66]

Hi folks!

I am assembling a M301 printer... and I'm pretty close to start printing.... I used an infrared termometer to check differences between heatbed's real termperature and setpoint shown on the machine lcd. I found the real temperature 30 Celsius lesser than the setpoint... Would like to change the sensor position but probably it would require a change in regulator PID constants. Does the M303 code work on this printer?

Thanks for every suggestion

Bye from Italy

[William]

First, you need to tell me what is the target temperature you set for the heat bed in Rostock 301? If this is the reason for the hardware structure, the temperature of the heat bed cannot be adjusted via changing the PID constants.

[lele66]

Hi,

I set 100 °C target temperature for the heatbed.... it's the suggested temperature for ABS printing. The lcd screen shows a pretty fast reaching of the target but in practice the MEASURED temperature of the hb is about 30 °C lower than the expected value. I asked how to adjust PID just in case of sensor placing change.

Any suggestions?

Thanks in advance

[William]

You should check whether heat bed resistance, thermistor is normal, PID regulation ability is limited, only to adjust the deviation within 5C

[lele66]

Hi

I don't know what's the right value of the heatbed resistance but I'll let you know what I measure. I asked for the M303 feature in order to avoid instability of the system targeting heatbed setpoint after a change in sensor placement. I know it's the last resource - I'll try to increase thermal isolation by adding a cork layer under the heatbed.

Thanks in advance for any suggestion