MMU2s Suddenly selecting wrong filament
The past two weeks I've been printing a series of 2 color panels for a modular synthesizer I'm building. This has been working fairly well up until Friday. I haven't changed my workflow or any settings in Prusa slicer or on the printer - but suddenly when I'm running prints the printer is selecting the wrong filament.
I'm using Filaments #2 and #3 which are white and black PLA respectively. I have #4 and #5 loaded with PETG which I'm not using on this current project.
In Prusaslicer it correctly shows extruder #2 and #3 being used:
But when I run the print instead of changing to #3 it changes to #4 (and the printer display says it's loading #4 so it's not that it thinks it's loading #3 and getting #4 by mistake somehow.)
I've looked at the gcode but am not familiar with the codes used for filament change and couldn't find specs on them to figure out if this is a slicer issue or a printer issue.
Any ideas what could be causing this?
RE: MMU2s Suddenly selecting wrong filament
I have had several issues with strange MMU2 behavior that were all fixed by disconnecting and reconnecting MMU2 control cables at the main board. You might give this a try.
RE: MMU2s Suddenly selecting wrong filament
I'll give the old disconnect/reconnect a try.
For reference I uploaded the current g-code that's giving me issues here:
https://gist.github.com/jhitesma/45f05512be6c8f2d6a126eda6c8cd4bb
It looks like T1/2/3/4 are the commands that should change filament...but even though this print only uses extruders 2 and 3 I only see T1 and T2 commands in the gcode so there seems to be something I'm really not understanding about MMU gcode.
RE: MMU2s Suddenly selecting wrong filament
Figured it out! Just watched another attempt more carefully.
After it finished with extruder 2 and goes to do the first filament change it does load filament 3. Then makes 2 passes across the wipe tower - but nothing appears to come out. Then it unloads filament 3 and displays a message saying loading filament #4 and starts to load #4.
Which had me scratching my head why it would do that...until I remembered I have spool join on.
Apparently my #3 filament (black, hatchbox - even though my profile says Prusament I've found I get really good results with hatchbox on the prusament presets.) which is nearing the end of the roll has gone a bit brittle and snapped inside the PTFE between the buffer and the MMU. It wasn't visible because every time I looked the ends were pressed against each other and where it was positioned in the tube.
I only found it because I decided to try reloading #3 and when I did I finally noticed the break.