Second Order Base Point

Sometimes, only the first order base point is not enough when dimension an engineering drawing.
Adaucogit Salt is a powerful plug-in for AutoCAD software. Its automatic dimensioning function also has the ability to determine whether the drawing needs second order base points and where to locate them.

The below drawing was annotated by Salt automatic dimensioning function.

1. “Point 1” is the first order base point.
2. There is an non-orthogonal group of entities at left-top of the drawing. The program automatically specified a second order base point (Point 2) for this group and used the point to dimension the group.
3. Use Salt automatic leader to describe holes.
4. Angle of bevel cannot be annotated automatically because it is involved mating alignment. Concerning the quadrant and the mating tolerance is important. (more discussion)

P.S. Try to think about how to annotate this drawing clearly by using ordinate dimensioning.