MakerGear Forum

morganfree wrote:What could be that issue?

That's a PID loop with a bit too much P or I gain, so it oscillates.

Run a firmware PID auto-tune, store the results in EEPROM, and the temperature should be stable.

Thanks Ed!
Well, I did the PID auto-tune but it seems that the T continues unstable... it seems a little bit less, but not as stable as I use to see it.

Should be the heater again? I just replace it...
Should I do the process more than once?

I'm printing just fine, but those variations are noticeable at part's exterior surface, especialy with PLA.

Any other idea?

Thanks a lot!

morganfree wrote:Should I do the process more than once?

Once is enough: the numbers represent the best fit for a given set of conditions.

However, if you did the tuning from a room-temperature start, you may get better results by manually preheating the extruder to about 200 C before auto-tuning.

Remember to store the final results in EEPROM! If you don't, then the new values Go Away when you turn the power off. Next time, the firmware will fetch the old values from the EEPROM, just as if you did nothing.

I see, I'll do the tune again with the manually preheating.

Yes, I'm storing the results with the M500 code ( M500 P**** I**** D****). I guess it's ok.

I'll let you know later about the new setup.

Thanks

morganfree wrote:M500 P**** I**** D****

I think you don't need the PID parameters, just the M500, but, given the number of Marlin variations in the wild, there's absolutely no way to tell.

If you can look at the console log when you turn it on, you should see a dump of the parameters the firmware is using: it's the the only way to be sure.

You aren't saving the PID properly.

It's something like M301 P** I** D** to change the values in RAM, then a single M500 afterwards to commit all the firmware values to EEPROM.

insta wrote:change the values in RAM

Huh. Yet Another Marlin Variation.

At least some Marlins update their in-RAM variables as part of the auto-tune sequence, so they're ready for the store-to-EEPROM step.

Definitely check the serial log to see what emerges when the thing starts up ...

hahahaha it finally works as insta said.

M301 bla bla bla to upload the values
M500 to save them to EEPROM

Thanks a lot. T steady as hell!!!

Regards!

The more "I told you so" tiffs Ed and I get into, the better the community is as a whole

insta wrote:The more "I told you so" tiffs Ed and I get into

Damn straight!

We need a sticky thread of ITYS gotchas ...