Overextrusion out of nowhere

[Arminas]

Hello,

I have a problem with a random over-extrusion (picture below). Everything was printing great for a couple of hours and then suddenly printer started to over-extrude.. RatRig vcore 3.1 with 1LC toolboard, Duet 3 mini, RRF 3.4.6. Any ideas..?

[oliof]

@Arminas first suggestion is to update to RRF 3.5.1 to see if the error persists. There was a bug with miscounting steps on extruders on toolboards that got fixed at least (although that usually led to no extrusion at all when it occurred) ...

[Arminas]

@oliof Okay I will try it. But I have another printer with exact same configuration, and there are no problems.

[Arminas]

@oliof I have new theory - maybe it's not overextrusion, but Z axis is not going down properly? I have 2 basically identical CoreXY printers. I just found out that the printer's with this "overextrusion" problem motors are getting way hotter than the other CoreXY printer's motors. Could this be an issue? And how should I validate this theory?

[oliof]

@Arminas could be related, either due to mechanical deficiencies in one build or die to issues with the motors themselves, or due to unintended differences in the configuration.

In order of complexity, I would

• compare the configurations(simple with a diffing program on a PC)
• re-check that the Z motion parts and linear guides are parallel and square
• swap the z motors between machines (how annoying that is depends on your builds and whether you can disconnect the cables motor side)

[Arminas]

@oliof Config is exactly the same, mechanical side is good, everything runs smooth and easy. Is there a way to check if the board is at fault or not?

[Arminas]

@oliof Okay I am pretty sure now that it has something to do with the mainboard or toolboard. Extruder motor gets extremely hot and then over extrusion happens. Printer is not enclosed.

[gloomyandy]

@Arminas A lot of work I know, but try swapping the toolboards over between the two machines? See if the problem moves or not?