Drafting Zone

Datums Study Guide

A datum is a theoretically exact plane, axis, line, or point. A datum does not actually exist on a workpiece or tool since these items have imperfections. Datums are located from the inexact features on a part. The imperfect features on a workpiece that are used to establish a datum location or orientation are known as datum features. Datum features are physical entities. They are not theoretical entities such as centerlines, axes, or reference planes. Datum features are imperfect, but the associated datum is theoretical and therefore perfect. A tolerance specification that controls a feature relative to datums must include one or more datum references. The references are shown in a feature control frame.

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Datums Study Quiz

This Study Quiz is designed to test your knowledge of the material covered in the Datums Study Guide. This Quiz will begin as soon as you click the "Begin Quiz" link.

Number of Questions: 5

Passing Score: 850

Time Limit: 10 minutes

Begin Quiz

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