Help tweaking PETG + PLA support interface settings (supports touching model)

Software Snapmaker Orca
1

I’m trying to dial in multi-material supports and could use some advice from anyone who’s gotten this working well.

My setup is:

  • Model material: PETG
  • Support material: PETG
  • Support/Raft Interface: PLA (so the PLA should be the only material contacting the model)

The issue I’m seeing is that some of the PETG support branches appear to extend past the PLA interface layers and actually touch the model. There are also some support areas that don’t appear to get interface layers at all.

From the preview, it looks like the PETG support is making direct contact in places, which defeats the purpose of using PLA as the interface material.

(Screenshot attached)

Support settings

Support

  • Style: Tree Hybrid
  • Threshold angle: 15°
  • On build plate only: :white_check_mark:
  • Remove small overhangs: :cross_mark:

Filament for Supports

  • Support/Raft Interface: PLA
  • Avoid interface filament for base: :white_check_mark:

Advanced

  • Top Z distance: 0.16 mm
  • Top Interface Layers: 3
  • Bottom Interface Layers: 2
  • Top Interface Spacing: 0
  • Bottom Interface Spacing: 0
  • Support/Object XY Distance: 0
  • Independent Support Layer Height: :white_check_mark:

Tree Supports

  • Tree Support Branch Angle: 60°

Questions

  1. Is it expected that tree support branches can extend past the interface and touch the model?
  2. Why would some support regions not receive interface layers at all?
  3. Are there settings I should adjust to ensure the PLA interface is the only material contacting the model?
  4. Is this a limitation/bug with Tree Hybrid supports, or should I be using a different support style for PETG + PLA interfaces?

Any suggestions or examples of working PETG/PLA multi-material support settings would be greatly appreciated.

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See below - the supports generated appear to extend past the interface layers and are touching the model. Additionally, there are supports generated that don’t appear to have interface layers at all.

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2

I had the same problems, but with PETG as an interface layer for PLA.
I checked visually the GCode layer by layer and indeed, at some points no interface is coded for printing. I am not sure, but I think that I used “Strong Trees” to circumvent the problem. I consider it a major bug in Orca Slicer.

3

I was able to get it to work:

Threshold Angle: 30
Top Z Distance 0 ← this seems to be the trick

Top Interface layers: 3
Interface pattern: Rectilinear
Top interface spacing: 0
Independent support layer height: checked

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