Possible bug when unloading filament
Bit of background, I work at a school and we have 10 3d printers, some are MK4 out of the box some were MK3 and were converted. We teach 3d printing and design so it's enough to say there is a lot of printing going on everyday.
The issue I'm having is that on our MK4s that came new out of the box a few months ago, when some of the printers run out of filament and I remove the filament and on the screen the printer displays "Has the filament been unloaded yes/no" I select "yes" after unloading it the printer still thinks there is filament in the extruder (filament still being detected). This essentially brings an end to the printer printing and there is no menu choice to override the filament detection and no other menu options at all. The only thing I can do is reset the printer and that causes the print job to be lost. All printers have the latest firmware (26 Aug 2024). This will happen at random and is not isolated to one printer.
I will add that this only seems to occur 30+ after the printer detects that it ran out of filament and displays the inactivity message. And it has never occurred when a filament change is commanded in the menu. It feels like there is a bug that does not wake up the filament detector after the inactivity timer shows up on the screen.
Thank you
To confirm: The issue is with just one printer and the same files print OK with the same filament on other machines?
Cheerio,
RE: Possible bug when unloading filament
The problem appears at random and not just on one printer. No correlation between filament colors or brands.
The event usually goes as follows:
-Printer runs out of filament and filament detector detects this.
-Printer has been waiting longer than 30min for the filament to change and then shuts off the nozzle heat and displays this information on the screen,
-I remove filament and the select "yes" on the screen as the printer is asking if the filament has been removed.
-The screen displays "remove the filament from from the extruder"(something close to that) even though the filament has been removed.
-At that point there are no options on the screen for me to select. The only thing that comes up is if I hold down the selector knob/button I get a z axis adjustment screen that give me no other place to go.
I may try to reproduce this today and get some pictures so that it's clearer whats going on.
I've not seen this one - the first place I would look is in the sensor - is the overcooked and reheated filament leaving strings that might trigger it...?
Cheerio,
RE: Possible bug when unloading filament
I may have figured it out
When the filament runs out and the printer has been sitting for a while I get this
If I select "yes" BEFORE I pull out the filament
I get this and there is no way to escape from this menu other than resetting the printer. No amount of filament insertion and removal has any effect other than resetting the printer and then the print is lost.
RE: Possible bug when unloading filament
I am also getting this message on my MK4 every time I use the function 'Change Filament' or I use a Colour swap in the slicer and cannot move forward other than switching off the machine.
If however I use 'Unload Filament' and then use 'Load filament' it works but will not work with the 'Change Filament' option.
RE: Possible bug when unloading filament
I have since solved the issue by removing and cleaning the filament sensor, found a tiny piece of filament stuck to the ball bearing. Everything is now working as it should.
https://help.prusa3d.com/article/filament-sensor-mk4-mk3-9-xl_465702