Step 1: Level or Spatial Alignment
This must always be done before measuring any other feature. It helps to separate feature types by their 3-D (spatial) vs. 2-D (planar) nature.
Use:
Planes: Define the direction perpendicular to it-for example, the top plane on a part.
Cylinders and cones: Define the direction parallel to its main axis.
3-D lines: Define the direction three-dimensionally parallel to it-for example, the axis of a shaft.
Do not level to a line unless it is constructed to be truly 3-D.
Don’t Use:
Circles, 2-D lines, points or spheres. Remember this principle: Circles and 2-D lines are dependent on a reference or work plane. Therefore, these are bad choices for level.
As a word of caution, remember that lines and cylinders get their vector direction from the order in which they are measured or constructed-for example, the first to last point for lines.