PID auto tune assistance

[Bredmond]

Good morning all,

I just switched over to a new hot end, the Prometheus V2, and I am having some issues with tuning the PID of the thermistor.

I am having large swings I the hot end temp @240 for printing ABS, down to as low as 227 and as high as 251. On the original hexagon hot end that came with the machine I didn't notice more than an occasional 1 or 2 degree difference, right now the temp is constantly swinging through the range of ~227 -~250.

Using pronterface I've run the M303 (M303 S240 C10) command several times, and I seem to come up with different results ever time I run it. My current settings are:

P: 11.32
I: 0.52
D: 62.10

Does it matter what temp the nozzle is t when you start auto tune?

What at about different temps? If I autotune at the default, just using M303, at 150 will that be a bad setting for printing ABS @ 240?

I'm running a print right now, but afterwards I will let the hot end cool and rerun autotune and post those results also.

Thanks for any advice!

Bill

[Bredmond]

Here is what I got when running from a cold start:

PID Autotune start bias: 127 d: 127 min: 234.53 max: 241.67
bias: 115 d: 115 min: 236.25 max: 245.00
bias: 132 d: 122 min: 233.75 max: 248.33
Ku: 21.30 Tu: 28.84
Clasic PID
Kp: 12.78
Ki: 0.89
Kd: 46.07
bias: 102 d: 102 min: 235.00 max: 248.33
Ku: 19.48 Tu: 29.10
Clasic PID
Kp: 11.69
Ki: 0.80
Kd: 42.51
bias: 119 d: 119 min: 228.75 max: 248.33
Ku: 15.47 Tu: 42.07
Clasic PID
Kp: 9.28
Ki: 0.44
Kd: 48.83
bias: 126 d: 126 min: 229.00 max: 248.33
Ku: 16.60 Tu: 40.50
Clasic PID
Kp: 9.96
Ki: 0.49
Kd: 50.41
bias: 136 d: 118 min: 231.25 max: 246.67
Ku: 19.49 Tu: 29.49
Clasic PID
Kp: 11.69
Ki: 0.79
Kd: 43.11
bias: 120 d: 120 min: 229.75 max: 252.92
Ku: 13.19 Tu: 39.45
Clasic PID
Kp: 7.91
Ki: 0.40
Kd: 39.03
bias: 132 d: 122 min: 229.00 max: 246.67
Ku: 17.59 Tu: 31.06
Clasic PID
Kp: 10.55
Ki: 0.68
Kd: 40.97
bias: 117 d: 117 min: 233.52 max: 255.00
Ku: 13.87 Tu: 40.11
Clasic PID
Kp: 8.32
Ki: 0.41
Kd: 41.72

Note the differences in the results from a hot start and a cold start:

Hot start:
m301 p11.32 i.52 d62.1


Cold start:
M301 p8.32 i.41 d41.72

Now going to see if this holds temp any better at 240 with these new values.

Bill