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My PEEK fan wasn't spinning so I replaced it. Afterward, my hot end couldn't get up to temperature because the fan was cooling it down too much. SO, I figured I needed to re-run autotune but that didn't fix the problem. If I set the temperature to 235C then it'll get to 232C and then start cutting back the power to the hot end and so it never reaches 235C. My "fix" is to put my finger on the fan to stop it until it makes it up those last 3 degrees. What is the right way to fix the problem?

What is the max PID value set to in the EEPROM?

jetpad,

How are you finding out your true hot end temperature? What kind of device do you use?

Polygonhell wrote:What is the max PID value set to in the EEPROM?

I've got EEPROM disabled but in the source

P is 71.31
I is 8.23
D is 154.51

and EXT0_PID_MAX is 255

inventabuild wrote:jetpad,

How are you finding out your true hot end temperature? What kind of device do you use?

I was trying to use a kitchen digital thermometer but wasn't successful. So I haven't really used anything yet. I've got http://www.amazon.com/gp/product/B0084JQL1Q on order.

You can try manually increasing P and decreasing D.

Polygonhell wrote:You can try manually increasing P and decreasing D.

Thanks. I wasn't sure how those worked.

I have a similar issue when attempting to reach temperatures over 215C. Reduce the fan slider to 50% and it should work alright. If you are printing at that temperature you're probably not using PLA, which means PEEK temperature is not quite as important.

I had this exact symptom when I installed my peek fan. For a while I was just setting the temp a 3 degrees higher than I actually wanted. Then I insulated the heater block with that ceramic tape & kapton tape. Now I can reach temp, although it's oscillating back and forth in a 6 degree range about once minute. I reran autotune a few times, but not sure what else to do.


P = 34.5
I = 3.13
D = 95.05

Generally you want to set PIDMAX to as low as you can and still have it reach temperature relatively quickly. This alone will probably fix the oscillation.
If it's still oscillating too much, generally reduce I and increase D.
There are a lot of descriptions of PID tuning, autotune isn't always great.

OK well I reran autotune at a higher setpoint (M303 S225) over the weekend and picked new values based on that. It seems to have worked because it's staying between 232.5 and 231.5. I'm not at the printer now, so I don't have the actual values handy. I remember P was in the 20s.

My pidmax is still 255.