From the course: Introduction to Geometric Dimensioning and Tolerancing

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Basic GD&T terms

Basic GD&T terms

From the course: Introduction to Geometric Dimensioning and Tolerancing

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Basic GD&T terms

- [Instructor] In getting started with geometric dimensioning and tolerancing, it is helpful to be familiar with several frequently used terms, including datum, features and feature of size, feature control frame, maximum material condition, and least material condition. A datum is a reference geometry that serves as an origin for measurements. Datums can be points, axis, planes, or some combination of these. A datum feature is the CAD geometry that the datum is attached to. Typically mating surfaces in an assembly are chosen as datum features. This allows measurements to be made which reflect the ability of the parts to be properly mated together. Typically, a datum feature is the geometry that an inspector would place onto a feature to serve as the reference point for validating the geometry of a part. Parts are designed by creating a collection of geometric forms, such as surfaces, edges, pins, holes, tabs, and more. These geometric forms are commonly referred to as part features…

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