## Creating a Runout Feature Control Frame Dimension

Runout FCF dimensions are often used to determine the coaxiality of a selected feature with respect to a selected datum or datums. You must select at least one datum when creating a runout FCF dimension.

There are two types of runout:

- Circular Runout - Checks just one level of hits, one circle, around a cylindrical feature.

- Total Runout - Checks multiple levels of hits along the entire surface of the cylinder.

In addition, the Feature Control Frame tab of the GD&T dialog box contains two options buttons, Axial and Radial:

- If the considered feature is a plane or set of planes, only the Axial option is permitted and PC-DMIS automatically grays out both buttons and selects Axial.

- If the considered feature is an axial type feature, PC-DMIS selects Radial by default unless you define a single plane datum, in which case PC-DMIS automatically selects Axial and grays out both buttons.

Axial Runout

This type of runout is measured on the end surface of a cylindrical part. The end of the cylinder can be measured as a circle or a plane.

- Circular Axial Runout - PC-DMIS looks at each circle section separately (this implies sets of circles and sets of circle scans, not a plane or set of points). It computes the axial runout tolerance for each circle section based on the minimum spread of two parallel planes perpendicular to the datum axis, containing all the points of that circle section. The reported circular axial runout tolerance is the worst case of these individual circle sections.
  Available feature types for the considered feature are: scans, circles, sets of scans, and sets of circles.

- Total Axial Runout - PC-DMIS finds two parallel planes perpendicular to the datum axis, as close together as possible while still containing all the measure points (for all scans or circles taken together). The spread of these two parallel planes is the total axial runout tolerance.
  Available feature types for the considered feature are: scans, circles, planes, sets of scans, and sets of circles.

Radial Runout

This type of runout is measured on the cylindrical surface of a bore or shaft.

- Circular Radial Runout - PC-DMIS looks at each circle section separately (this implies sets of circles, sets of circle scans, or a cylinder with multiple circle sections, not a plane or set of points). It computes the radial runout tolerance for each circle section based on the minimum spread of two concentric circles centered on the datum axis, containing all the points of that circle section. The spread of these two concentric circles is the circular radial runout for that circle section. The reported circular axial runout tolerance is the worst case of these individual circle sections.
  Available feature types for the considered feature are: scans, circles, cylinders, cones, spheres, sets of scans, sets of circles, sets of cylinders, sets of cones, and sets of spheres.

- Total Radial Runout - PC-DMIS finds two concentric cylinders centered on the datum axis that are as close together as possible while still containing all the measure points (for all scans or circles or cylinders taken together). The spread of these two concentric cylinders is the total radial runout tolerance.
  Available feature types for the considered feature are: scans, circles, cylinders, cones, spheres, sets of scans, sets of circles, sets of cylinders, sets of cones, and sets of spheres.

Single Datums

Both circular and total runout (axial and radial) require at least one datum.

- If only one datum is specified and the runout type is Radial, then the datum must be an axial type feature (cylinder, cone, line).

- If only one datum type is specified and the runout type is Axial, then the datum may be an axial type feature or a plane.

Two Datums

If the runout type is Radial, then you may specify two datums.

- The primary datum is generally a plane that lies nominally perpendicular to the axis of the considered feature (which in this case would be an axial type feature).

- The secondary datum would be an axial type feature.

Compound Datums:

The datum may also be a compound datum that references two cylinders (such as A-B). If the runout type is Radial, then you may specify two datums.

- The primary datum is generally a plane that lies nominally perpendicular to the axis of the considered feature (which in this case would be an axial type feature).

- The secondary datum would be an axial type feature.