Chapter 10 Dimensioning
271
Figure 10-43 shows an example of positional
tolerancing with the maximum material
condition (MMC) modifi er applied and the
corresponding interpretation. Figure  10-44
shows an example of positional tolerancing with
the least material condition (LMC) modifi er
applied and the corresponding interpretation.
In both fi gures, the table at the bottom indicates
the tolerance at each produced hole size and
the amount of bonus tolerance resulting from
the application of the material condition
modifi er. The values in the table are diameter
values.
B
A
Goodheart-Willcox Publisher
Figure 10-42. A datum is identified by a letter inside
a box attached to a solid triangle. A datum is used to
indicate an exact point, axis, plane, or surface from
which features are located.
At maximum material condition
(or maximum material boundary)
Diameter
Radius
Basic dimension
Reference dimension
Counterbore
Countersink
Depth/deep
Square (shape)
Dimension not to scale
Number of times/places
Datum feature
Between
Straightness
Flatness
Circularity
Cylindricity
Profile of a line
Profile of a surface
Angularity
Perpendicularity
Parallelism
Position
Concentricity
Symmetry
Circular runout
Total runout
At least material condition
(or least material boundary)
Geometric Tolerance Specification Symbol Symbol
Type of
Tolerance
Geometric Characteristic
Form
Profile
Orientation
Location
Runout
Goodheart-Willcox Publisher
Figure 10-41. The drafter uses various symbols to identify geometric characteristics in the application of geometric
dimensioning and tolerancing. The table on the left shows the five standard types of geometric characteristic
symbols applied to communicate form, profile, orientation, location, and runout. The table on the right shows
additional symbols used in the GD&T system. The application of GD&T symbols on drawings supports precision
manufacturing and the global economy.
Copyright Goodheart-Willcox Co., Inc.