Orientation Tolerances

Orientation tolerances control the angle or direction of a feature relative to a reference (datum). Unlike form tolerances, they always require a datum.

1. Parallelism

Controls how parallel a feature is to a datum.

• Can apply to a surface or an axis
• Tolerance zone:
  • Two parallel planes (for surfaces)
  • A cylindrical zone (for axes)

👉 Ensures uniform spacing and proper alignment in assemblies.

2. Perpendicularity

Controls how close a feature is to a 90° angle relative to a datum.

• Applies to surfaces or axes
• Tolerance zone:
  • Two parallel planes at 90° (surface)
  • Cylindrical zone at 90° (axis)

👉 Critical for parts that must fit or assemble at right angles.

3. Angularity

Controls the angle of a feature relative to a datum at any specified angle (not 0° or 90°).

• Applies to surfaces or axes
• Tolerance zone: two parallel planes at the specified angle

👉 Used for inclined features like chamfers or angled holes.