/sdk/_docs/base/49_hinges.md

Hinges

Purpose

Use these helpers for exposed utility hinges that should show real leaves, knuckles, and pin geometry.

Import

from sdk import (
    BarrelHingeGeometry,
    PianoHingeGeometry,
    HingeHolePattern,
    HingePinStyle,
    mesh_from_geometry,
)

Recommended APIs

Shape intent	Helper
Exposed two-leaf utility hinge	BarrelHingeGeometry
Continuous hinge strip	PianoHingeGeometry
Leaf hole pattern	HingeHolePattern
Visible pin-end detail	HingePinStyle

API Reference

BarrelHingeGeometry

BarrelHingeGeometry(
    length,
    *,
    leaf_width_a,
    leaf_width_b=None,
    leaf_thickness,
    pin_diameter,
    knuckle_outer_diameter=None,
    knuckle_count: int = 5,
    clearance: float = 0.0005,
    open_angle_deg: float = 180.0,
    holes_a: HingeHolePattern | None = None,
    holes_b: HingeHolePattern | None = None,
    pin: HingePinStyle | None = None,
    center: bool = True,
)

• Builds an exposed two-leaf barrel hinge around a local Z pin axis.
• center=False places the lower end on z=0.
• Use HingeHolePattern for round or slotted leaf holes and HingePinStyle for visible pin-head variants.

PianoHingeGeometry

PianoHingeGeometry(
    length,
    *,
    leaf_width_a,
    leaf_width_b=None,
    leaf_thickness,
    pin_diameter,
    knuckle_pitch,
    clearance: float = 0.0005,
    open_angle_deg: float = 180.0,
    holes_a: HingeHolePattern | None = None,
    holes_b: HingeHolePattern | None = None,
    pin: HingePinStyle | None = None,
    center: bool = True,
)

• Builds a continuous hinge strip around a local Z pin axis.
• knuckle_pitch controls the repeating hinge pattern along the strip.
• center=False places the lower end on z=0.

Advice

• Use these helpers only for visible utility hinges. If the mechanism is a concealed cabinet hinge or a custom linkage, model it directly.
• Preserve real knuckle/pin logic. Do not replace a visible hinge with two flat plates and a decorative cylinder.

Examples

barrel_hinge = BarrelHingeGeometry(
    0.090,
    leaf_width_a=0.024,
    leaf_width_b=0.020,
    leaf_thickness=0.0024,
    pin_diameter=0.003,
    holes_a=HingeHolePattern(style="round", count=3, diameter=0.0032, edge_margin=0.010),
    holes_b=HingeHolePattern(style="slotted", count=2, slot_size=(0.007, 0.003), edge_margin=0.012),
)
barrel_hinge_mesh = mesh_from_geometry(barrel_hinge, "barrel_hinge")

piano_hinge = PianoHingeGeometry(
    0.180,
    leaf_width_a=0.016,
    leaf_width_b=0.014,
    leaf_thickness=0.0018,
    pin_diameter=0.0025,
    knuckle_pitch=0.012,
)
piano_hinge_mesh = mesh_from_geometry(piano_hinge, "piano_hinge")

See Also

• 40_mesh_geometry.md for lower-level mesh construction helpers