Issue with HE heater

Morane_3803

@Phaedrux
the temperature starts normal up to the setted 220°C.
It overshots the 220 up to 227 / 228. Then it settles to around +/- 3°.
After start printing the temperature starts to move extremly.
By means first within down to arround 215 up to 223.
But suddenly it drops and drops down to finally 203.
Where at 205 the systems pauses itself and stop printing.
No I'm not using a nozzle sock. Earlier I did use some!

As I mentioned above, the first prints after upgrading to RRF3.2 went well.
The problem became active during this long print!

Strange anyway.

jay_s_uk

@Morane_3803 I guess its when the fan comes on and the firmware is struggling to compensate for the temperature swing.
Have you PID tuned the hotend as a tool rather than a hotend? E.g. M303 T0 S220
Also its best to fit a sock to protect from temperature changes caused by the fan

jens55

I know you said that you already replaced the thermistor but in my experience, when the temperature fluctuates rapidly (as in instantaneous), it is either a bad contact in the thermistor line someplace or more often a dud thermistor.
If the temperature drops gradually over the period of say 30 seconds or more then you can have a heater or heater wire problem.
This happened to me just a few days ago and although the screw connections to the heater wire on the Duet were what I considered 'tight', i tightened them just a tad more and it solved all my problems. I suspect that I had some oxidation.
The other issue I have seen was when I used regular dupont type connectors when extending the heater wires. The connections heated up causing a higher resistance with time and a lower power output for the heater over time. I ended up going with a 24V power supply to cut the current in half.

Phaedrux

@Morane_3803 said in Issue with HE heater:

WiFi firmware version 1.23

I think you've missed updating the wifi firmware.

Upload this full zip file, as is, to the system tab. That should take care of everything that needs updating.

https://github.com/Duet3D/RepRapFirmware/releases/download/3.2.2/Duet2and3Firmware-3.2.2.zip

I think @jay_s_uk is on to something with tuning the hotend heater as a tool to take the fan into account.

Morane_3803

@jay_s_uk
The testpart is that big that the cooling fan did not even start yet.
It will turn on beginning at layer 2
M303 T0 220 i will try. I believe it was M303 H1 220 I've tried!

Ok and the socks I have and will put it on again!
I will report again.
Thanks a lot

Morane_3803

@jens55
Hi Jens55
this is an interesting view I did not consider yet. Even though I changed the cabling from H1 to H2 and vise versa.
I'm using 24V power supply.
I will check those kind off possible errors and report again.
Thanks a lot

Morane_3803

@Phaedrux
Hi Phaedrux
just did uploaded the ZIP-file. I will try tomorrow evening and will report again.
Thanks a lot and have a great evening!
Martin

theruttmeister

If you have trouble getting the PID dialed in, you can always change how sensitive the thermal error check is.
(If saw, you have a really low mass hot-end and you keep meaning to do the auto-tune propperly but squirrel........)

Sorry, where was I?

Oh yes.

M570

If you know that your fan on tool 0 causes a 15 degree drop that only lasts 20 seconds (and isn't causing printing issues) you might put in:

M570 H0 P30 S20

IMHO the default error parameters are quite strict... but I can't say that's bad, I know people will shoot video of the burning printer before they try and put out the fire

Morane_3803

Hi there
Today I've tried all the suggestions you gave...but no changes at all
But you wouldn't believe what I found!
Jens55 wrote about the cable issue. So finally I tried another file to print, a much smaller part as the other
which I first had that issue.
All printing went well. PID on H1 worked just perfect.
As a conclusion I believe there is a problem with the heater cable within the nice cable drag chain.
Most probably the cable is somewhere broken or overstretched, whatever!
So tomorrow evening I change this cable and give it another trial.
Stand by.
Anyway guys thanks a lot for your help. One way or the other, I've lerned a lot.
Regards Martin

Morane_3803

Hi
Today I replaced this faulty cable and everything works fine!
It is unbelievable but a fact!
Thanks to all of you guys for the support.
Have a great time!
Regards Martin