Extruder motor suddenly getting extremely hot

[Vinculum]

@rjenkinsgb I don't think it is under extrusion. As you see in the second picture, the Sideview, it starts with a neat layer stacking but when it goes into overdrive you see that it expands beyond the layers beneath. That is a sign of overextrusion. And in the pictures below that you see the plowing happening.

I do agree that that is what may increase the motor temp. It tries to push so much plastic and the hotend can't melt it that fast. Plus the nozzle will get blocked due to the amount of plastic beneath it. But not due to under extrusion.

Besides of it it a temp issue or not, the printer should signal it and stop but it doesn't.

[Vinculum]

Well i need the machine to work so I ripped the toolboard out of my home printer and just layed a lot of wires. Problem fixed.

But now, I wanted to use the toolboard as an upgrade to my work printers. Totally different design. But similar 6HC mainboard and a new 1LC toolboard. This time a v1.2. Guess what? Same issue!

Start great and suddenly it goes into overdrive.

I made a cross post in this topic (https://forum.duet3d.com/topic/26697/toolboard-1lc-heater-falut-mid-print/7?_=1641814629460) where someone has at least part of the symptoms I have. Here is what I had this morning:

Had a 88 hour print and it failed midway. Temp sensor says 2000 degrees but the printer doesn't go into error mode, it just continues.
I then stopped the print, decoupled the thermistor and connected a brand new one. Temp still at 2000.
Reset just the board with the 2 buttons, no effect. Reset the board with M999 B121, no effect. Unplugged the power from the toolboard, no effect.
Only after pressing the reset button on the 6HC it came back online and with the original temperature sensor...
All run the same firmware, 3.4.0beta7.

That was this morning. I then did a restart of the print and the result is above. Again 2000 degrees, printer goes into overdrive and print failes. But printer still keeps on moving...

[engikeneer]

@hbm-3d I'm not so involved in this so please feel free to tell me to butt out...

In the picture you show, that looks a lot like an overheated print (which may also have overextrusion). I note that it starts where the print changes from a large infilled section to a thinner section. Is this seen in your other larger test prints? Given the 2000C thermistor it seems there is something going on with temperature control?

I believe it is a current firmware limitation that heater faults on expansion boards are not reacted to. You can however query them via the object model (I think?) so could run your own checks via daemon.g for the meantime. I think this is planned to be fixed in RRF3.5 (check the firmware limitation Wiki page for more details).

I wonder if the reason you need to reset the 6HC is because the toolboard loses its config, so you need to run config.g again. Maybe try just calling M98 P"config.g" next time to see? Might help narrow down the debug options

[rjenkinsgb]

@hbm-3d
I'd guess you have a CAN bus problem; interference from other wiring, bad termination or a bad connection, so some data is being corrupted and causing the system to misbehave.

A power brownout that did not cause a full reset at the toolboard could also give a similar effect, again possibly a bad connection somewhere?

Are the CAN connections either twisted pair in each run, or well separated from other wiring ?