Setting Top/Bottom Extruder does not use that extruder for walls of those layers.

[BadMouth 0]

I have an IDEX and would like to print the top and bottom layers with a small nozzle while using a large nozzle on the layers in between.

 

In Cura if I set the extruder with the large nozzle as the one to print the object and set Top/Bottom Extruder to the one with the small nozzle it still uses the large nozzle for the walls of the top and bottom layers.  This is with Wall Extruder set to "Not Overrridden".

 

I could set Wall Extruder to the small nozzle, but that prints the walls of all layers with the small nozzle which would result in a toolhead change on every layer.  It is also no different than just setting the large nozzle as the Infill Extruder.

 

Is there any way to make Top/Bottom Extruder take precedent over Wall Extruder for those layers?

 

That is what would work best for my purposes anyway.

I can't think of a use case for the current behavior except for printing multi-color prints with different color walls.

That would be covered by setting the Wall Extruder rather than leaving it "Not Overridden".

 

Thank you for reading.

 

 

 

[GregValiant 1,357]

Bring in a Support Blocker.  Scale it and position it where it will affect the top layer.  Set it to the extruder with the small nozzle.  Make it 1 layer thick and when positioned correctly it should only affect the top layer.

In the "Per Model" settings set the blocker as a Cutting Mesh.

 

This is the top layer with a 0.2 nozzle.

 

This is the layer below with a 1.0 nozzle.

 

Here the blocker is only covering a portion of the top layer.

[BadMouth 0]

Thank you.  That works for the bottom layer which is most important to me. 

It's not ideal for top layers of different shapes at different heights, but at least it gets the first layer correct.

 

I still think Top/Bottom Extruder not using the correct extruder for the walls is a bug.

Where would be the most proper place to report that as a bug or requested improvement?

 

[GregValiant 1,357]

There are a lot of extruders but they need to be related to what they are going to be used for.

        wall_extruder_nr
        wall_0_extruder_nr
        wall_x_extruder_nr
        roofing_extruder_nr
        top_bottom_extruder_nr
        infill_extruder_nr
        support_extruder_nr
        support_infill_extruder_nr
        support_extruder_nr_layer_0
        support_interface_extruder_nr
        support_roof_extruder_nr
        support_bottom_extruder_nr
        skirt_brim_extruder_nr
        adhesion_extruder_nr
        raft_base_extruder_nr
        raft_interface_extruder_nr
        raft_surface_extruder_nr

The way it is written is that a "Wall" is a wall but can be refined to Outer Wall (0) and Inner Wall (x).  A Top/Bottom is a Skin but a Skin isn't necessarily a Top Bottom.

I'm not seeing a bug, it's the way it works.  Flexible definitions for a niche situation would make a mess for a lot of people.

Unfortunately you can't really post process or hand edit your gcode because of the difference in nozzle sizes.  All the extrusions would be at an incorrect volume.