Huge swings in extruder temperature

have you auto PID tuned again for the new cartridge?

I have no idea how to do that.  How do I go about doing that?

Nevermind, I search and found the Wiki on PID tuning.

Ok, so it seems that no matter what I do, I can't run the Autotune command without getting the "Temperature too high" error. 

It doesn't matter if I try to autotune it to 200°, or 100°.  I also tried a variety of solutions offered elsewhere like adding the E-0 to the command line to specify the extruder instead of the bed, whether I had the extruder heater off or on when I started the Autotune. 

End result:  "PID Autotune failed! Temperature too high"

So I decided to do some trial and error settings, and this is what I came up with this far:

I started with some arbitrary numbers in the neighborhood of the original PID settings. This shows a swing of about 10°C, 5° above and 5° below the primary target.  P is set to 20, I is zeroed out and D is set to 120

Then I decreased P to half, and got a much flatter response (in fact it's less than 1° after about 10 minutes).  But you'll notice that the average temperature is now 5° below the target, at 185°C.

Increasing the I to 1.00 brought the average temperature up to 195°,and also introduced a wild swing of almost 15°C, so I backed the number down incrementally, until I got to 0.1.  The average temperature is now 190° (target), and the oscillations are about 1°

But no matter what I do, I can't seem to get rid of the huge overshoot on the first cycle, when I turn on the heater.  Even if the heater was turned off for only a minute, on the initial heatup, it overshoots the target by at least 10°.  According to some of the documents I read, increasing the value of P, should reduce the overshoot, but for me, it has the opposite effect, and it introduces the wild oscillations.

For now, I can live with the current settings, but any insights on how to reduce the overshoot, or anything else for that matter, would be appreciated.

Hi all.

I found that the PID tuning works great to keep the temperature stabilized. What temp do you guys run at for ABS? I find that 205c I get the best layer adhesion (If I go much lower the layers don't stick together as good) but when printing tall but narrow parts, the heat it gives off seem to burn the layers and darken the color or my orange ABS.

I finally had a chance to get back to this, and found the solution.  The problem I had with autotune triggering MAXTEMP was solved by reducing PID_MAX from 255 to 190.  This reduces the maximum current sent to the heater during PID.

Now I was able to run the PID autotune command and get some numbers.  The autotune values were very close to the numbers I had stumbled on manually.  But what made a difference was the current reduction using the PID_MAX. 

While I was at it, I also enabled and ran a PID on the bed, and saved the values.

While the bed is functioning flawlessly, the extruder heater still has the overshoot, but it no longer goes near the 220° mark.  I will try to reduce the PID_MAX value further and see if that reduces the overshoot.

It's in the configuration.h file. 

I downloaded this Solidoodle/Arduino file, and modified it's configuration.h file to reflect the changes I needed.  Then built and uploaded the new firmware.

http://download1897.mediafire.com/4fasn … indows.zip

Download the file, extracted to a working directory (needs about 260MB), then run the Arduino executable.    Load the Solidoodle sketch ("File/Example/SolidoodleMarlin"), then on the configuration.h tab make the necessary changes.  Then either build the new hex file or upload it to the printer directly.  make sure you select the correct board and COM port.

Hope this helps.