Marcin: /* Wall Module Schema → FreeCAD Geometry Compiler */

2026-01-21T07:01:21Z

Wall Module Schema → FreeCAD Geometry Compiler

← Older revision		Revision as of 07:01, 21 January 2026
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	= Wall Module Schema → FreeCAD Geometry Compiler =		= Wall Module Schema → FreeCAD Geometry Compiler =
			https://chatgpt.com/share/69707955-7ca4-8010-850a-ca6cef5201ee

	This page defines the canonical transformation from a ''wall module specification'' (schema instance) into deterministic CAD geometry in FreeCAD.		This page defines the canonical transformation from a ''wall module specification'' (schema instance) into deterministic CAD geometry in FreeCAD.

Marcin: Created page with "= Wall Module Schema → FreeCAD Geometry Compiler = This page defines the canonical transformation from a ''wall module specification'' (schema instance) into deterministic CAD geometry in FreeCAD. == Scope == * Wall modules built from 2x6 framing, 24" OC * Optional OSB sheathing on Face A (7/16") * Optional openings: Window (RO width/height, sill height, x position) Door (RO width/height, centered in 4' module by default) * Flush-built header: (2) 2x12 members,..."

2026-01-21T06:56:29Z

Created page with "= Wall Module Schema → FreeCAD Geometry Compiler = This page defines the canonical transformation from a ''wall module specification'' (schema instance) into deterministic CAD geometry in FreeCAD. == Scope == * Wall modules built from 2x6 framing, 24" OC * Optional OSB sheathing on Face A (7/16") * Optional openings: ** Window (RO width/height, sill height, x position) ** Door (RO width/height, centered in 4' module by default) * Flush-built header: (2) 2x12 members,..."

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= Wall Module Schema → FreeCAD Geometry Compiler =

This page defines the canonical transformation from a ''wall module specification'' (schema instance) into deterministic CAD geometry in FreeCAD.

== Scope ==
* Wall modules built from 2x6 framing, 24" OC
* Optional OSB sheathing on Face A (7/16")
* Optional openings:
** Window (RO width/height, sill height, x position)
** Door (RO width/height, centered in 4' module by default)
* Flush-built header: (2) 2x12 members, biased to Face A

== Canonical Principle ==
A module is defined as ''data'' (specification), not as geometry.
CAD geometry is a compiled artifact produced deterministically from the spec.

== Inputs ==
=== Required fields ===
* module.id
* module.width_in
* module.height_in
* module.stud_spacing_oc_in (default 24)
* plates.top_plate_count (default 2)
* plates.bottom_plate_count (default 1)
* sheathing.thickness_in (default 7/16), sheathing.side = "A"
* openings[] (optional)

=== Opening fields ===
For each opening in openings[]:
* opening.id
* opening.type: "window" or "door"
* opening.rough_opening.width_in, height_in
* window: opening.sill_height_from_bottom_in
* placement:
** window: opening.x_from_left_in
** door: opening.centered_in_module=true OR opening.x_from_left_in
* header: lumber="2x12", members=2, bias_to_face="A"

== Coordinate System (CAD Convention) ==
* X = module width (left→right)
* Y = wall thickness (Face A at y=0; Face B at y=+5.5)
* Z = height (bottom at z=0)

All schema lengths are in inches. Compiler converts to mm for FreeCAD internal units.

== Output (Geometry Contract) ==
FreeCAD document (.FCStd) containing:
* Containers (groups):
** WallModule
*** Framing
**** Plates
**** Studs
**** Openings (per-opening subgroups)
*** Sheathing
* Solid bodies for each physical part:
** Plates, studs, kings, jacks, headers, sills, cripples
** OSB panels (as thin solids on Face A)
* Deterministic naming for downstream drawing + BOM automation:
** Example: TP_0, BP_0, STUD_03, W1_JACK_L, D1_HEADER_2PLY_2X12, OSB_00, etc.

== Compiler Pipeline ==
=== Step 0: Validate Spec ===
* Confirm required fields exist
* Confirm module width/height are within allowed ranges (implementation-defined)
* Confirm door constraints (v0 default):
** single door module width must be 48" unless explicitly overridden

=== Step 1: Derive Constants ===
Assume nominal-to-actual conversions:
* 2x thickness = 1.5"
* 2x6 depth = 5.5"
* 2x12 depth = 11.25"

Compute:
* wall_thickness = 5.5"
* plate_thickness = 1.5"
* stud_length = module.height_in - plate_thickness*(top_plate_count + bottom_plate_count)

=== Step 2: Place Plates ===
* Bottom plate(s) at z = 0..1.5"
* Top plate(s) at z = module.height_in - 1.5*top_plate_count .. module.height_in
* Door special case (v0): split bottom plate around door RO span

=== Step 3: Generate Base Stud Grid ===
Define stud centerlines with 24" OC:
* Always include end studs
* Interior studs at: x = x_start + n*OC

Create studs as 1.5" x 5.5" x stud_length solids placed at:
* y = 0
* z = 1.5*bottom_plate_count

=== Step 4: Compile Openings (Replace Studs + Add Framing) ===
For each opening:
1. Compute RO rectangle:
* x0, x1 from placement + RO width
* z0, z1 from sill height (window) or 0 (door) + RO height
2. Remove any base studs whose x-span overlaps [x0, x1]
3. Add kings (full height) at the outside of the opening assembly
4. Add jacks (trimmers) at opening edges from bottom plates up to header bearing
5. Add header:
* length = RO.width + 2*1.5" (v0 bearing rule)
* depth = 11.25" (2x12)
* thickness = 3.0" (two 2x members laminated)
* biased to Face A: header placed at y=0..3.0"
6. Add cripples above header up to underside of top plates on the 24" grid
7. Window only:
* Add sill member at z = sill_height + 1.5" (v0)
* Add cripples below sill down to top of bottom plates

=== Step 5: Panelize OSB Sheathing on Face A ===
Place OSB as thin solids on Face A at y = -OSB_thickness..0.

Height sourcing policy:
* If module.height_in <= 108": use a single 9' sheet (cut to height)
* Else if module.height_in <= 120": use a single 10' sheet (cut to height)
* Else: use 8' sheet + remainder pieces to reach full height

Width policy (v0):
* If width <= 48": one panel (rip to width)
* If width <= 96": two panels (48" + remainder)
* If width > 96": tile in 48" increments + remainder

The panelizer outputs a list of rectangles {w,h,x,z} which become OSB solids.

=== Step 6: Emit Geometry ===
The compiler creates FreeCAD objects using primitive solids (Part::Box or PartDesign solids):
* Each part is created as a separate object
* Each part has deterministic name and placement
* Objects are added into the group tree for downstream automation

=== Step 7: Recompute + Save ===
* doc.recompute()
* doc.saveAs("<module.id>.FCStd")

== Minimal Pseudocode ==
<pre>
spec = load(schema_instance)
validate(spec)

W,H,OC = spec.module.width, spec.module.height, spec.module.stud_spacing_oc
top_n, bot_n = spec.plates.top_count, spec.plates.bottom_count

stud_len = H - 1.5*(top_n + bot_n)

create_plates(W,H,top_n,bot_n)

stud_centers = make_stud_centers(W, OC)
base_studs = create_studs(stud_centers, stud_len)

for opening in spec.openings:
ro = compute_opening_rect(opening, W)
delete_overlapping_studs(base_studs, ro.x0, ro.x1)

add_kings_and_jacks(ro)
add_header(ro, members=2, size="2x12", bias="FaceA")
add_cripples_above(ro)

if opening.type == "window":
add_sill(ro)
add_cripples_below(ro)

panels = panelize_osb(W,H, spec.sheathing.policy)
create_osb_solids(panels, face="A")

recompute_and_save()
</pre>

== Determinism Rules ==
To ensure compile reproducibility:
* No interactive sketching
* No manual edits downstream of compilation
* Stable naming conventions for every generated part
* Same spec input must produce identical part counts, placements, and names

== Notes ==
This is a geometry compiler spec, not a structural engineering standard.
Structural detailing (nailing schedules, corner conditions, advanced header sizing, etc.) are layered as additional schema fields and compiler rules in later versions.

Wall Module Specification - Revision history

Marcin: /* Wall Module Schema → FreeCAD Geometry Compiler */