• 1-888-TEC-EASE
  • Outside USA: 1-716-785-6015
Free Tec-Ease Mug GD&T Textbooks GD&T Training GD&T Public Seminars GD&T Computer Based Training GD&T Reference Material
A Complex Feature as a Datum Feature May Constrain
(In accordance with the ASME Y14.5-2009 standard)

PDF of this Tip

There is a new chart in the ASME Y14.5-2009 standard that shows the degrees of freedom that are constrained when the feature is a primary datum feature and, where appropriate, applies RMB. The chart also shows the relationship between the feature type, simulator and theoretical datum(s) that are established. This series of six Tips illustrate the features shown in the chart. Although some of the simulators are illustrated as physical inspection equipment, these simulators may also be simulated by "soft gaging" optical or probing methods.

Complex Feature

A complex feature is defined as a single compound curve or a collection of other features that constrains up to six degrees of freedom.

This revision of the Standard declares that any feature may be used as a datum feature. Here, a complete datum reference frame is established by a complex feature. Where this datum feature A is referenced in a feature control frame, a secondary or tertiary datum feature would have no meaning.

The video for this Tip is from Don’s new computer based training course on GD&T Fundamentals available on DVD and the internet.

Back to Tips Tip added Apr 2010