Creating Dimensions

This task shows you how to create a dimension annotation.
The task deals with:

See Dimension Units reference for dimension unit display.
  • When the dimension supports are related to a parameter (sketch constraints, knowledge, etc) for which tolerances are still defined,
    they are set to the dimension tolerances.
  • Minimal distance can be created between canonical surfaces (revolution or planar surfaces) or the projected edge, in the current annotation plane, of a non-canonical surface.
 

Creating Dimensions
Open the Annotations_Part_04.CATPart document:

  1. Activate the Front View.2 annotation plane.

  1. Click Dimensions  in Annotations toolbar.

  1. Select the surface as shown on the part.

  2. Click anywhere to create it.

    The dimension is created.

  3. Drag the dimension.

    The Dimension Properties toolbar displays three combo boxes:
    • Line Type to select the Dimension Line attachment.
    • Tolerance Description to display the tolerance according to a standard.
    • Tolerance Display to valuate the tolerance dimension.

    The Numerical Properties toolbar display two combo boxes:

    • Numerical Display Description to set the numerical tolerance display.
    • Precision to set the tolerance precision.

  1. In the Dimension Properties toolbar, select TOL_NUM2 in the Tolerance Description combo box, and +-0.05 in the Tolerance combo box (the dimension is still selected).

    Tolerances are displayed with the dimension.
 

Creating Minimum Dimensions
Open the Annotations_Part_02.CATPart document:

  1. For the purpose of this scenario, click Dimensions in Annotations toolbar.

  1. Select the surface as shown on the part.

  1. Click anywhere to create the dimension.

  2. Right-click the dimension and select Force dimension on element from the contextual menu.

    The dimension is created as shown.

  3. Again right-click to open the contextual menu, then select the Minimum Distance type for your dimension.

  1. Position the minimum distance dimension, then click to validate its creation.

 

About the Minimum Distance Dimension

Limitations

  • If the minimum distance between two geometries can be reached at several different locations, only one is selected by the minimum distance dimension.
  • When a minimum distance dimension is created, it cannot be changed into a distance dimension.
  • The measure of minimum distance is performed on the geometry projection in the dimension view plane, so that minimum distance dimension cannot be created as a true length dimension, within an isometric view.
  • As for all dimensions, it is not possible to create a minimum distance dimension on a surface that is not canonical.
  • A minimum distance dimension cannot be created as a semantic annotation.
     

Update

As for all dimensions, any update or geometry modification re-computes a minimum distance dimension.

A minimum distance dimension cannot be null. If geometries are modified and are intersecting with each other, the update will not re-compute the minimum distance dimension. The minimum distance dimension will be displayed as not up-to-date, with its extension line being displayed till the last valid position (i.e. when curves were not intersecting each other).