Like datum planes, datum axes can be used as references for feature creation. Datum axes are particularly useful for making datum planes, placing items concentrically, and creating radial patterns.

You can use a datum axis as a reference to place set datum tag annotations. If no datum axis exists, selecting the geometry to which the set datum tags are associated, such as a circular curve or edge or the edge of a cylindrical surface, automatically creates an internal datum axis. The set datum tags are placed normal to the datum plane referencing the datum axis or the cylindrical surface associated with the datum axis.

Datum axes can also be created using Sketcher. If you create a geometry centerline in a sketch feature, when you return to the modeling environment, the result is a datum axis.

Datum axes, as opposed to feature axes, are individual features that can be redefined, suppressed, blanked, or deleted. They can be previewed during their creation. You can specify a value as the axis length or adjust the axis length to visually fit to an edge, surface, datum axis, a feature in Part mode, or a part in Assembly mode selected as a reference. The outline of the reference is used to determine the length of the datum axis.

Datum axes receive a name in the format A_# by default, where # is the number of datum axes that have been created.

You can set an initial name for a datum axis during the creation process by using the Properties tab in the Datum Axis dialog box. Or, if you want to change the name of an existing datum axis, you can right-click the datum feature in the Model Tree and choose Rename from the shortcut menu.