Tronxy X3A Extruder Temperature

The extruder temperature on my Tronxy X3A likes to run about 1.5 degrees below the setpoint.  I don't know how much effect that has on the quality of my prints, but I do know that until the temperature difference gets less than 1 degree, the print won't proceed if the M109 code has been used in the program.

As a workaround, I just blocked the airflow to the extruder fan with a card, the temperature went up slightly, and the test print proceeded.

But now I want to fix it so it works properly.  I think I want to do an autotune cycle.

I did an autotune by following the procedures on Using Repetier Host with my Tronxy X3A.

PID Constants from Autotune

Here are the results of the autotune:

Kp = 17.44
Ki = 1.19
Kd = 63.71

After entering these values from Repetier host, the temperature control is perfect.

Entering PID Constants

Now that I have the constants, they need to be installed in the printer.  This is done by the following:

1. Send an M205 to the printer.  This will display a list of all the EEPROM settings.

2. In the list, find the PID settings for the extruder.  On my printer, they are  as follows:

EPR:3 218 17.4400 Extr.1 PID P-gain/dead-time
EPR:3 222 1.1900 Extr.1 PID I-gain
EPR:3 226 63.6996 Extr.1 PID D-gain

The first number following EPR is the type.  All are type 3 (float).
The second number following EPR is the position in EEPROM.  218 for Kp, 222 for Ki, 226 for Kd.
The third number is the value (17.44 for Kp, 1.19 for Ki, 63.6996 for Kd).

3. Set values by sending an M206 command to the printer.  The M206 command to set Kp to 17.5 would be as follows:

M206 T3 P218 X17.5

Note that the T parameter is the type, the P parameter is the position,  and the X parameter is the value to be stored in that position
4. Once you have set all 3 values, you should have the new PID constants set.