Example: Selecting the Base Part

The base part is fixed in the tolerance analysis, and from it, all remaining parts are assembled. When you select the base part in the Assembly Sequence PropertyManager, consider which part should establish the coordinate system of the worst case assemblies and the directions of measurement.

In this example, you create a study to determine the minimum result for the inside distance between the two vertical legs.
The only tolerances you apply are perpendicularity tolerances to the base.
These tolerances result in this worst case part.
Base part = left leg
Base part = center base
Base part = right leg
In each case, the base part remains fixed and oriented to the assembly coordinate system and the measurement remains along its X-axis.

The results vary by a spread of 2.