Page 1 of 1

Jittery temps

Posted: Fri May 17, 2019 2:39 pm
by jsc
I'm getting my first temp issues after many years. One of my extruders exhibits jittery temps when heating up and cooling down, spikes of several degrees up and down. I'm guessing this is an incipient thermistor failure? What else might it be?

Oh, and look at that, I just received "Error: 1: Extruder switched off. MINTEMP triggered !" while extruder 1 was cold. Must be?

Re: Jittery temps

Posted: Fri May 17, 2019 5:56 pm
by airscapes
Yup most likely, order more than one they don't go bad sitting on your shelf so you have it when you need it!
Once you get it you should do an auto pid calibration. Not sure how to do it on a dual extruder but on the single of the M2
From terminal enter
It will turn on the extruder and do some readings and adjustments
When it is done it spits out a line and tells you to add the last output of the P I D values above to the config.
You would then enter
M301 Pxx.xx Ix.xx Dxx.xx
M500 (to save)

I use octoprint which will disconnect saying no response in 3 minutes or something.
Reconnect and run the cal again for good measure.

I have 3 different hot ends for 3 nozzle sizes so I have he M301 value strings saved so I can enter them when I switch hot ends.
Good luck!

Re: Jittery temps

Posted: Wed May 22, 2019 12:16 am
by jsc
I got my (2) replacement thermistors, and everything's working again. Just out of curiosity: there's no set screw for the thermistor, it just sits in its hole on the v4 hot end?

Re: Jittery temps

Posted: Thu May 23, 2019 1:51 am
by ednisley
jsc wrote:
Wed May 22, 2019 12:16 am
it just sits in its hole on the v4 hot end?
MG would have far too many troubles with a teeny setscrew:
  • It'd require a super-teeny hex wrench nobody has
  • Teeny threads gall & seize when repeatedly heated
  • Folks would crush the thermistor by over-tightening
So, better to let it just hang in there.

I gooped it up with heatsink compound, which surely make zero difference, but I felt better: ... libration/