Operations¶

Operations transform sketches into 3D geometry, modify existing bodies, or reshape edges.

extrude¶

extrude(
    sketch: PlacedSketch | SketchPrimitive,
    amount: float = None,
    through: bool = False,
    to: FaceRef = None,
    name: str = "",
) -> Body

Push a 2D sketch into a 3D solid along the face normal.

Parameter	Description
`sketch`	A placed sketch (from `.place_on()` or `.place_at()`)
`amount`	Extrusion distance in mm. Positive = outward from face, negative = inward
`through`	If `True`, extrude far enough to cut through any body (uses 1000mm)
`to`	Extrude until reaching this face
`name`	Name for the resulting body

Extrusion direction

The extrusion direction is always along the face normal. When placed on plate.top, a positive amount goes upward (+Z). When placed on plate.front, it goes outward (-Y).

Basic extrusion¶

from llmcad import Box, Rect, extrude

plate = Box(100, 60, 10)

# Extrude a boss 20mm upward from the top face
boss = extrude(Rect(30, 30).place_on(plate.top), amount=20)
plate = plate + boss

Through extrusion¶

# Cut a hole all the way through
hole = extrude(Circle(10).place_on(plate.top), through=True)
plate = plate - hole

Extrude to a face¶

# Extrude from bottom up to the top face
boss = extrude(Rect(20, 20).place_on(plate.bottom), to=plate.top)

Named extrusions¶

When you name an extrusion, the end cap face gets special naming:

boss = extrude(Rect(30, 30).place_on(plate.top), amount=20, name="boss")
plate = plate + boss

# The end cap is accessible:
plate.faces["_end"]

Automatic face naming¶

After extrusion, faces are automatically named:

_start --- the face at the extrusion origin
_end --- the face at the extrusion end
wall --- cylindrical face (for circular extrusions only)
Standard faces (top, bottom, front, back, left, right) are assigned based on face normals

revolve¶

revolve(
    sketch: PlacedSketch | SketchPrimitive | Sketch,
    axis = None,
    angle: float = 360,
    name: str = "",
) -> Body

Revolve a 2D sketch around an axis to create a solid of revolution.

Parameter	Description
`sketch`	A sketch (placed or primitive)
`axis`	Axis of rotation (`gp_Ax1`, or `body.center_axis`). Default: Z axis
`angle`	Revolution angle in degrees (default 360 for full revolution)
`name`	Name for the resulting body

from llmcad import Rect, revolve

# Create a donut shape by revolving a rectangle around Z axis
profile = Rect(5, 10).place_at(origin=(20, 0, 0), normal=(0, 1, 0))
ring = revolve(profile, angle=360)

# Partial revolution (180 degrees)
half = revolve(Rect(10, 20).place_at(origin=(30, 0, 0), normal=(0, 1, 0)), angle=180)

loft¶

loft(
    sketches: list[SketchPrimitive | PlacedSketch | Sketch],
    heights: list[float],
    name: str = "",
) -> Body

Loft between multiple sketches at specified Z-heights to create a smooth transition.

Parameter	Description
`sketches`	List of 2D sketches to loft between
`heights`	Z-height for each sketch (must match length of `sketches`)
`name`	Name for the resulting body

from llmcad import Circle, Rect, loft

# Transition from circle at bottom to rectangle at top
body = loft([Circle(40), Rect(30, 30)], heights=[0, 50])

Named faces: top (highest Z), bottom (lowest Z).

sweep¶

sweep(
    path: Sketch | PlacedSketch,
    cross_section: PlacedSketch | SketchPrimitive | Sketch = None,
    name: str = "",
) -> Body

Sweep a cross-section along a path to create a solid.

Parameter	Description
`path`	A Sketch defining the sweep path (wire)
`cross_section`	The profile to sweep along the path
`name`	Name for the resulting body

from llmcad import Sketch, Circle, sweep

# Create a curved pipe
path = Sketch()
path.start(0, 0)
path.line_to(50, 0)
path.arc_to(80, 30, radius=30)
path.line_to(80, 80)

pipe = sweep(path, cross_section=Circle(10))

shell¶

shell(
    body: Body,
    thickness: float,
    open: list[FaceRef] = None,
    name: str = "",
) -> Body

Hollow out a solid body, leaving walls of the specified thickness.

Parameter	Description
`body`	The body to hollow
`thickness`	Wall thickness in mm
`open`	Faces to remove (leave as openings)
`name`	Optional name

Shell before features

Apply shell() before cutting holes or adding detailed features. Shelling a body that already has holes can produce errors.

from llmcad import Box, shell

box = Box(80, 60, 40)
enc = shell(box, thickness=2, open=[box.top])
# enc is now an open-top box with 2mm walls

After shelling, faces gain .inner and .outer variants:

enc.front.inner   # inner wall of the front face
enc.front.outer   # outer wall (same as enc.front)

split¶

split(
    body: Body,
    plane = None,
    name: str = "",
) -> Body

Split a body with a plane, keeping the half on the positive side of the plane normal.

Parameter	Description
`body`	The body to split
`plane`	A `gp_Pln` plane. Default: XZ plane (splits front/back)
`name`	Optional name

from llmcad import Sphere, split

sphere = Sphere(50)
half = split(sphere)  # keeps the positive-Y half

mirror¶

mirror(
    body: Body,
    plane = None,
    name: str = "",
) -> Body

Mirror a body about a plane.

Parameter	Description
`body`	The body to mirror
`plane`	Mirror plane (`gp_Ax2`, `gp_Pln`). Default: YZ plane (mirrors across X)
`name`	Optional name

from llmcad import Box, mirror

box = Box(40, 30, 20)
mirrored = mirror(box)  # mirrored across YZ plane
result = box + mirrored  # symmetric shape

fillet¶

fillet(
    edges,
    radius: float,
    name: str = "",
) -> Body

Round edges with a circular cross-section.

Parameter	Description
`edges`	`EdgeRef`, list of `EdgeRef`, or edge collection from `face.edges`
`radius`	Fillet radius in mm
`name`	Optional name for the resulting body

from llmcad import Box, fillet

box = Box(50, 50, 50)

# Fillet all edges of the top face
box = fillet(box.top.edges, radius=5)

# Fillet a single edge
box = fillet(box.top.left_edge, radius=3)

# Fillet specific edges
edges = [box.top.left_edge, box.top.right_edge]
box = fillet(edges, radius=2)

Parent body

fillet() automatically finds the parent body from the edge references. The edges must belong to the same body.

chamfer¶

chamfer(
    edges,
    size: float,
    name: str = "",
) -> Body

Bevel edges with a flat cut.

Parameter	Description
`edges`	`EdgeRef`, list of `EdgeRef`, or edge collection
`size`	Chamfer size in mm
`name`	Optional name for the resulting body

from llmcad import Box, chamfer

box = Box(50, 50, 50)

# Chamfer all top edges
box = chamfer(box.top.edges, size=3)

Face name preservation¶

After fillet() and chamfer(), face names from the original body are automatically transferred to the new body. This means you can keep chaining operations:

plate = Box(100, 60, 10, name="plate")
boss = extrude(Rect(30, 30).place_on(plate.top), amount=20)
plate = plate + boss
plate = fillet(plate.top.edges, radius=3)
plate = chamfer(plate.bottom.edges, size=2)

# plate.top, plate.bottom, etc. still work