Definition
Angularity is a geometric tolerance that controls the allowed deviation of a surface or axis from a specified angle relative to a reference plane (a datum), for any angle other than ninety degrees.
What it means for the calculation
An angled feature with a tight angularity tolerance often needs a dedicated fixture, an angled set-up or a 5-axis operation, which changes machine choice and cycle time compared with a square feature.
Where it appears on the drawing
In a feature control frame with the ∠ symbol, a basic angle dimension, a tolerance value and a datum letter.
Common mistakes
Treating a toleranced basic angle as a normal ± angle dimension. Also forgetting that the basic angle itself carries no tolerance of its own: the tolerance sits in the feature control frame.
An angled feature with a tight angularity tolerance often needs a dedicated fixture, an angled set-up or a 5-axis operation, which changes machine choice and cycle time compared with a square feature.
See how Blake reviews a partFrequently asked questions
What is a "basic angle"?
A theoretically exact angle (boxed on the drawing) with no tolerance of its own; the angularity callout carries the tolerance.
Is angularity only for flat surfaces?
No, it also applies to axes, such as an angled hole or bore.
Why not just use a ± angle dimension instead?
Because a ± angle dimension has no datum reference, so it does not control the relationship to the rest of the part the way angularity does.