Wall Module Schema

https://chatgpt.com/share/69706dec-54ac-8010-a171-74eb64954e9a

Steps

1. Create schema
2. Create compiler.
3. Compile. This generated CAD in FreeCAD

Real Takeaway

You are no longer “designing wall modules.”

You are designing a wall-module language.

FreeCAD is just the rendering backend.

Schema

File:Wall module schema.yaml

Compiler

File:Wall module compiler.zip

Generate a Wall Module CAD File in FreeCAD (Schema → Compiler → .FCStd)

Prerequisites

1. Install FreeCAD (GUI and command-line support).
2. Create a working folder, e.g.:
   • ~/ose_wall_compiler/
3. Save these files into that folder:
   • wall_module_compiler.py (the compiler script)
   • One or more module spec files, e.g. WM_WALL_48x120.json, WM_WINDOW_48x120.json, WM_DOOR_48x96.json

Step 1: Create a module specification file (JSON)

1. In your working folder, create a JSON file such as WM_WALL_48x120.json.
2. Paste a minimal wall module spec:

{
  "schema_version": "wall_module_v0.1",
  "module": {
    "id": "WM_WALL_48x120",
    "type": "wall_panel",
    "width_in": 48,
    "height_in": 120,
    "stud_spacing_oc_in": 24,
    "plates": { "top_plate_count": 2, "bottom_plate_count": 1 },
    "sheathing": { "thickness_in": 0.4375 }
  },
  "openings": []
}

Step 2: (Optional) Create a window module spec

1. Create WM_WINDOW_48x120.json:

{
  "schema_version": "wall_module_v0.1",
  "module": {
    "id": "WM_WINDOW_48x120",
    "type": "wall_panel",
    "width_in": 48,
    "height_in": 120,
    "stud_spacing_oc_in": 24,
    "plates": { "top_plate_count": 2, "bottom_plate_count": 1 },
    "sheathing": { "thickness_in": 0.4375 }
  },
  "openings": [
    {
      "id": "W1",
      "type": "window",
      "rough_opening": { "width_in": 36, "height_in": 48 },
      "sill_height_from_bottom_in": 36,
      "x_from_left_in": 6,
      "header": { "type": "flush_built", "members": 2, "lumber": "2x12", "bias_to_face": "A" }
    }
  ]
}

Step 3: (Optional) Create a door module spec

1. Create WM_DOOR_48x96.json:

{
  "schema_version": "wall_module_v0.1",
  "module": {
    "id": "WM_DOOR_48x96",
    "type": "wall_panel",
    "width_in": 48,
    "height_in": 96,
    "stud_spacing_oc_in": 24,
    "plates": { "top_plate_count": 2, "bottom_plate_count": 1 },
    "sheathing": { "thickness_in": 0.4375 }
  },
  "openings": [
    {
      "id": "D1",
      "type": "door",
      "centered_in_module": true,
      "rough_opening": { "width_in": 36, "height_in": 80 },
      "header": { "type": "flush_built", "members": 2, "lumber": "2x12", "bias_to_face": "A" }
    }
  ]
}

Step 4: Run the compiler (headless) to generate the FreeCAD file

1. Open a terminal in the working folder.
2. Run FreeCAD in command-line mode (freecadcmd) to compile the JSON into an .FCStd file:

Wall module

freecadcmd wall_module_compiler.py WM_WALL_48x120.json WM_WALL_48x120.fcstd

Window module

freecadcmd wall_module_compiler.py WM_WINDOW_48x120.json WM_WINDOW_48x120.fcstd

Door module

freecadcmd wall_module_compiler.py WM_DOOR_48x96.json WM_DOOR_48x96.fcstd

Step 5: If TechDraw causes issues, disable drawings

1. Some FreeCAD installations may fail TechDraw in headless mode.
2. Re-run with drawings disabled:

freecadcmd wall_module_compiler.py WM_WINDOW_48x120.json WM_WINDOW_48x120.fcstd --no-drawings

Step 6: Open the generated CAD file in FreeCAD (GUI)

1. Launch FreeCAD.
2. File → Open → select the generated .fcstd.
3. Inspect the model tree:
   • WallModule
   • Framing → plates / studs / openings
   • Sheathing → OSB panels

Step 7: Export geometry for fabrication workflows (optional)

1. Export 2D/3D formats as needed:
   • Select objects (or the WallModule group)
   • File → Export
   • Choose format:
     • STEP (.step) for interchange
     • STL for printing (if needed)
     • DXF for 2D cutting (typically from TechDraw or Draft)

Troubleshooting

1. Command not found: freecadcmd
   • On some systems it is named FreeCADCmd.
   • Try: FreeCADCmd wall_module_compiler.py ...
2. JSON parse errors
   • Validate commas and braces; JSON must be strict.
3. No TechDraw page appears
   • Use --no-drawings; geometry output is still correct.
   • Or generate drawings from within the FreeCAD GUI.

Output Contract (What You Get)

1. A deterministic FreeCAD model file: *.FCStd
2. Model contains real solids:
   • Plates, studs, king/jack studs, headers, sills, cripples
   • OSB sheathing panels sized per the sourcing rules
3. Optional: TechDraw page(s), depending on your FreeCAD setup