Multiextruder issues

[NBl 0]

Hello

I've been having some weird efects when using Cura 3.6 with my two extruders printer. I've two extruders but only one hotend, so currently I'm using only one of them at a time.

- First issue was when I was trying to print wit extruder 2 (Ext2) and 2.85mm filament. I don't know why, Cura introduced a long and very fast retraction just before printing the first layer. It started in 6 mm retraction at 100 mm/s and after some slicings the retraction growed to 18 mm. I have no starting gcode for any extruder.

 

[NBl 0]

(Posted before ending the message, sorry)

I had to manual edit and comment or delete the wrong gcode retraction line. I fixed it uninstalling, clearing profiles and installing again. I found no other solution.

- Now, the Slicer has starting to activate the wrong layer fan. I choose Ext1, checked all the config and after generating gcode i've found that Cura is trying to start layer fan 2. I've only one fan and Ext2 is disabled. 

Why could be happening this issues? What should I check to avoid this unexpected effects?

I've starting to think that there's some kind of bug in multiextruder handling

Thank you

[nallath 691]

Cura assumes that each extruder has one hotend. We can't really test for anything else, since all Ultimaker machines adhere to that assumption. 

[NBl 0]

Then why if I only use one extruder  (I disabled the other extruder) it keeps trying to start the layer fan of the disabled extruder?

[nallath 691]

That's probably because your firmware. Cura assumes that all commands it sends are for the active extruder. Some firmware has the (default) option enabled that when no extruder is specified with the command that it sees it at "do it for all extruders"

[NBl 0]

Thanks, but I think that this is not the case.  The gcode generated activates the right tool, but the M106 order is M106 P1 instead of M106 P0 (I should have refered to them as Ext0 and Ext1 instead of Ext1 and Ext2, 0 and 1 is how they´re named in Marlin). Both extruders use the same hotend and the same layer fan. I've config Marlin with "singlenozzle" option, as they both were part of a Cyclops extruder, but I currently use them separately with different filament diameter (Ext0 1.75 Ext1 3.00 mm). I know that this is not a common printer config, but I would like to know how to config Cura to swap between them without having to check and edit manually the GCODE to make sure everything is right each time I generate it.

 

Thank you.