/freecad-scripts

name: freecad-scripts
description: 'Expert skill for writing FreeCAD Python scripts, macros, and automation. Use when asked to create FreeCAD models, parametric objects, Part/Mesh/Sketcher scripts, workbench tools, GUI dialogs with PySide, Coin3D scenegraph manipulation, or any FreeCAD Python API task. Covers FreeCAD scripting basics, geometry creation, FeaturePython objects, interface tools, and macro development.'

FreeCAD Scripts

Expert skill for generating production-quality Python scripts for the FreeCAD CAD application. Interprets shorthand, quasi-code, and natural language descriptions of 3D modeling tasks and translates them into correct FreeCAD Python API calls.

When to Use This Skill

• Writing Python scripts for FreeCAD's built-in console or macro system
• Creating or manipulating 3D geometry (Part, Mesh, Sketcher, Path, FEM)
• Building parametric FeaturePython objects with custom properties
• Developing GUI tools using PySide/Qt within FreeCAD
• Manipulating the Coin3D scenegraph via Pivy
• Creating custom workbenches or Gui Commands
• Automating repetitive CAD operations with macros
• Converting between mesh and solid representations
• Scripting FEM analyses, raytracing, or drawing exports

Prerequisites

• FreeCAD installed (0.19+ recommended; 0.21+/1.0+ for latest API)
• Python 3.x (bundled with FreeCAD)
• For GUI work: PySide2 (bundled with FreeCAD)
• For scenegraph: Pivy (bundled with FreeCAD)

FreeCAD Python Environment

FreeCAD embeds a Python interpreter. Scripts run in an environment where these key modules are available:

import FreeCAD          # Core module (also aliased as 'App')
import FreeCADGui       # GUI module (also aliased as 'Gui') — only in GUI mode
import Part             # Part workbench — BRep/OpenCASCADE shapes
import Mesh             # Mesh workbench — triangulated meshes
import Sketcher         # Sketcher workbench — 2D constrained sketches
import Draft            # Draft workbench — 2D drawing tools
import Arch             # Arch/BIM workbench
import Path             # Path/CAM workbench
import FEM              # FEM workbench
import TechDraw         # TechDraw workbench (replaces Drawing)
import BOPTools         # Boolean operations
import CompoundTools    # Compound shape utilities

The FreeCAD Document Model

# Create or access a document
doc = FreeCAD.newDocument("MyDoc")
doc = FreeCAD.ActiveDocument

# Add objects
box = doc.addObject("Part::Box", "MyBox")
box.Length = 10.0
box.Width = 10.0
box.Height = 10.0

# Recompute
doc.recompute()

# Access objects
obj = doc.getObject("MyBox")
obj = doc.MyBox  # Attribute access also works

# Remove objects
doc.removeObject("MyBox")

Core Concepts

Vectors and Placements

import FreeCAD

# Vectors
v1 = FreeCAD.Vector(1, 0, 0)
v2 = FreeCAD.Vector(0, 1, 0)
v3 = v1.cross(v2)          # Cross product
d = v1.dot(v2)              # Dot product
v4 = v1 + v2                # Addition
length = v1.Length           # Magnitude
v_norm = FreeCAD.Vector(v1)
v_norm.normalize()           # In-place normalize

# Rotations
rot = FreeCAD.Rotation(FreeCAD.Vector(0, 0, 1), 45)  # axis, angle(deg)
rot = FreeCAD.Rotation(0, 0, 45)                       # Euler angles (yaw, pitch, roll)

# Placements (position + orientation)
placement = FreeCAD.Placement(
    FreeCAD.Vector(10, 20, 0),    # translation
    FreeCAD.Rotation(0, 0, 45),   # rotation
    FreeCAD.Vector(0, 0, 0)       # center of rotation
)
obj.Placement = placement

# Matrix (4x4 transformation)
import math
mat = FreeCAD.Matrix()
mat.move(FreeCAD.Vector(10, 0, 0))
mat.rotateZ(math.radians(45))

Creating and Manipulating Geometry (Part Module)

The Part module wraps OpenCASCADE and provides BRep solid modeling:

import FreeCAD
import Part

# --- Primitive Shapes ---
box = Part.makeBox(10, 10, 10)               # length, width, height
cyl = Part.makeCylinder(5, 20)               # radius, height
sphere = Part.makeSphere(10)                  # radius
cone = Part.makeCone(5, 2, 10)               # r1, r2, height
torus = Part.makeTorus(10, 2)                 # major_r, minor_r

# --- Wires and Edges ---
edge1 = Part.makeLine((0, 0, 0), (10, 0, 0))
edge2 = Part.makeLine((10, 0, 0), (10, 10, 0))
edge3 = Part.makeLine((10, 10, 0), (0, 0, 0))
wire = Part.Wire([edge1, edge2, edge3])

# Circles and arcs
circle = Part.makeCircle(5)                   # radius
arc = Part.makeCircle(5, FreeCAD.Vector(0, 0, 0),
                       FreeCAD.Vector(0, 0, 1), 0, 180)  # start/end angle

# --- Faces ---
face = Part.Face(wire)                        # From a closed wire

# --- Solids from Faces/Wires ---
extrusion = face.extrude(FreeCAD.Vector(0, 0, 10))       # Extrude
revolved = face.revolve(FreeCAD.Vector(0, 0, 0),
                         FreeCAD.Vector(0, 0, 1), 360)    # Revolve

# --- Boolean Operations ---
fused = box.fuse(cyl)           # Union
cut = box.cut(cyl)              # Subtraction
common = box.common(cyl)        # Intersection
fused_clean = fused.removeSplitter()  # Clean up seams

# --- Fillets and Chamfers ---
filleted = box.makeFillet(1.0, box.Edges)          # radius, edges
chamfered = box.makeChamfer(1.0, box.Edges)        # dist, edges

# --- Loft and Sweep ---
loft = Part.makeLoft([wire1, wire2], True)          # wires, solid
swept = Part.Wire([path_edge]).makePipeShell([profile_wire],
                                              True, False)  # solid, frenet

# --- BSpline Curves ---
from FreeCAD import Vector
points = [Vector(0,0,0), Vector(1,2,0), Vector(3,1,0), Vector(4,3,0)]
bspline = Part.BSplineCurve()
bspline.interpolate(points)
edge = bspline.toShape()

# --- Show in document ---
Part.show(box, "MyBox")    # Quick display (adds to active doc)
# Or explicitly:
doc = FreeCAD.ActiveDocument or FreeCAD.newDocument()
obj = doc.addObject("Part::Feature", "MyShape")
obj.Shape = box
doc.recompute()

Topological Exploration

shape = obj.Shape

# Access s