Why is Angularity used?
A tilted mating face can create a gap or point contact even when its nominal angle is dimensioned.
ORIENTATION CONTROL / GD&T SYMBOL GUIDE
ANGULARITY
Angularity controls a feature's orientation at a specified theoretically exact angle other than 0° or 90° to a datum. For a surface, the tolerance is the separation of two planes oriented at that basic angle.
INTERACTIVE APPLICATION
GD&T angularity example: 30° bracket face
WITH ANGULARITY
The inclined face is controlled from datum A
- The boxed 30° sets the theoretically exact angle.
- The leader connects the ∠ | 0.2 | A frame to the angled face.
What to read
- The lower face establishes datum A.
- 0.2 mm is a linear tolerance-zone width, not ±0.2°.
INTERPRETATION
The face stays in the angled zone
- Two parallel planes form a 0.2 mm zone at the basic 30° angle to A.
- The complete controlled face must remain inside that zone.
Practical meaning
- Angularity controls orientation and form relative to A.
- The frame does not by itself locate the face or set its size.
Where is Angularity used?
Angled brackets, dovetails, wedge faces, fixture ramps and machined or stamped mating surfaces.
How is Angularity used?
Mark the base as datum A, box the exact 30° angle as a basic or theoretically exact dimension, and attach the ∠ | 0.2 | A frame to the sloping face. The full face must stay inside the oriented two-plane zone.
Two planes 0.2 mm apart are oriented at the boxed 30° angle to datum A and enclose the whole face.
How it is used
Identify the lower face as datum A. Show the 30° angle as a basic dimension, then point the ∠ | 0.2 | A frame at the inclined face.
How to read the tolerance frame
Read angularity, the 0.2 mm two-plane zone, then datum A. The zone is oriented at the basic 30° angle to A; the whole indicated face must fit inside it.
Commonly defined variable values
The controlling value is a tolerance-zone width, not a universal process grade. For this angularity example, the drawing states the controlled feature and applicable extent.
Scroll the table sideways to see every column.
| Application | Illustrative starting value | Example feature | Notes / caution |
|---|---|---|---|
| Machined bracket face | 0.05–0.20 mm | 100 mm angled face | Specify a boxed/basic angle. |
| Precision dovetail | 0.02–0.10 mm | 100 mm slide | Inspect both mating faces. |
| Fabricated angled member | 0.3–1.0 mm | 200 mm member | Allow for weld distortion. |
These are planning examples, not universal rules or guaranteed process capabilities. Set the actual tolerance from function, size, length, process capability, inspection method and the standard specified on the drawing.
How is angularity measured in real life?
Establish datum A first. Measure the indicated feature and compare it with the requirement shown on the drawing.
- Sine bar + indicator: Seat datum A, set the nominal 30° angle and scan the inclined face for variation.
- CMM: Establish datum A, construct the theoretically exact angled zone and evaluate sampled face points.
- Optical comparator: For suitable profiles, compare the edge to a datum-aligned nominal-angle overlay; confirm it represents the full controlled surface.
ASME Y14.5-2018 (R2024)
ASME Y14.5 uses a basic angle and a linear zone width. The orientation control does not locate the face by itself.
ASME Y14.5 edition reference. Examples are learning schematics; use the complete requirements on the drawing.
LEARN BY DOING
Practise GD&T on engineering drawings
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