For those who have done Marlin's PID auto-tune on the stock hotend, how close and how stable have you been able to get the temperatures?
I'm following the instructions from here:
Even when letting it run for 25 cycles, it seems as though I still have a rather large range over which it oscillates. For example, here is the output from the end of my last run. With a target of 200 degrees, starting from cold, it initially has a considerable overshoot (~212 I think?), then quickly settles in to this sinusoidal range from 197-203 degrees.
bias: 68 d: 68 min: 197.24 max: 203.37 Ku: 28.28 Tu: 36.37
Kp: 16.97 Ki: 0.93 Kd: 77.14
bias: 67 d: 67 min: 197.36 max: 203.54 Ku: 27.59 Tu: 38.99
Kp: 16.55 Ki: 0.85 Kd: 80.69
bias: 68 d: 68 min: 197.02 max: 202.88 Ku: 29.52 Tu: 36.37
Kp: 17.71 Ki: 0.97 Kd: 80.54
bias: 68 d: 68 min: 197.27 max: 203.65 Ku: 27.17 Tu: 37.19
Kp: 16.30 Ki: 0.88 Kd: 75.79
PID Autotune finished! Put the last Kp, Ki and Kd constants from below into Configuration.h
#define DEFAULT_Kp 16.30
#define DEFAULT_Ki 0.88
#define DEFAULT_Kd 75.79
Is that normal to have a six degree oscillation of the temperature after tuning, or should it stabilize better than that?
This is on Marlin 1.1.8, for what it's worth.
Thanks in advance.