Interface Shells with Solid Modifiers Ignores Wall Count #2144

New Issue

MrUnknownDE · 2026-04-06T00:24:33+02:00

MrUnknownDE commented

2026-04-06 00:24:33 +02:00

Originally created by @Friendly3D on 9/18/2025

Is there an existing issue for this problem?

I have searched the existing issues

OrcaSlicer Version

2.3.1-beta.1

Operating System (OS)

macOS

OS Version

15.1

Additional system information

No response

Printer

Bambu X1C, P1P, A1M

How to reproduce

When using "Interface Shells" if you add a solid modifier to your object, the slicer will suddenly stop respecting your wall loops setting and only use a single loop (I've actually seen 0, but can't reproduce right now).

Open solid-modifier.3mf.zip
Slice + go to layer ~27
Observe wall count
Turn off "Interface Shells"
Change "Top shell layers" (see below)
Slice + go to layer ~27
Observe wall count

Note on top shell layers: Complicating the debugging of this is it seems like Orca might cache generation to some extent and toggling "Interface Shells" on/off doesn't invalidate that cache – so it may look like the issue isn't there until you save/restart; or what I've found as a way to invalidate existing cache is changing top layer count. It doesn't matter what value you set this to, just don't use a value you've previously used.

Actual results

Orca slices the outer perimeter with a single wall:

Expected results

Orca slices the outer perimeter with the expected number of walls:

Project file & Debug log uploads

solid-modifier.3mf.zip

Checklist of files to include

Log file
Project file

Anything else?

If you remove the solid modifier but keep interface shells on, it produces the appropriate number of walls.

*Originally created by @Friendly3D on 9/18/2025* ### Is there an existing issue for this problem? - [x] I have searched the existing issues ### OrcaSlicer Version 2.3.1-beta.1 ### Operating System (OS) macOS ### OS Version 15.1 ### Additional system information _No response_ ### Printer Bambu X1C, P1P, A1M ### How to reproduce When using "Interface Shells" if you add a solid modifier to your object, the slicer will suddenly stop respecting your wall loops setting and only use a single loop (I've actually seen 0, but can't reproduce right now). 1. Open [solid-modifier.3mf.zip](https://github.com/user-attachments/files/22414514/solid-modifier.3mf.zip) 2. Slice + go to layer ~27 3. Observe wall count 4. Turn off "Interface Shells" 5. Change "Top shell layers" (see below) 6. Slice + go to layer ~27 7. Observe wall count _**Note on top shell layers:** Complicating the debugging of this is it seems like Orca might cache generation to some extent and toggling "Interface Shells" on/off doesn't invalidate that cache – so it may _look_ like the issue isn't there until you save/restart; or what I've found as a way to invalidate existing cache is changing top layer count. It doesn't matter what value you set this to, just don't use a value you've previously used._ ### Actual results Orca slices the outer perimeter with a single wall: <img width="600" alt="Image" src="https://github.com/user-attachments/assets/e402ed42-f300-44cc-af38-207a975dd530" /> ### Expected results Orca slices the outer perimeter with the expected number of walls: <img width="600" alt="Image" src="https://github.com/user-attachments/assets/64c353a1-ff2f-4b8f-bf92-9bcf63076d12" /> ### Project file & Debug log uploads [solid-modifier.3mf.zip](https://github.com/user-attachments/files/22414514/solid-modifier.3mf.zip) ### Checklist of files to include - [ ] Log file - [x] Project file ### Anything else? If you remove the solid modifier but keep interface shells on, it produces the appropriate number of walls.

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Reference: github/OrcaSlicer#2144