Geometric Tolerancing

Geometric Tolerancing is used to specify the shape of features.

Things like:

•Straightness

•Flatness

•Circularity

•Cylindricity

•Angularity

•Profiles

•Perpendicularity

•Parallelism

•Concentricity

•And More...

Geometric Tolerances are shown on a drawing with a feature control frame.

The Feature Control Frame

This feature control frame is read as: “The specified feature must lie perpendicular within a

tolerance zone of 0.05 diameter at the maximum material condition, with respect to datum

axis C. In other words, this places a limit on the amount of variation in perpendicularity

between the feature axis and the datum axis. In a drawing, this feature control frame would

accompany dimensional tolerances that control the feature size and position.

Principles of Engineering Drawing

Thayer Machine Shop

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