2012

Table Of Contents
Projected Tolerance Zones
Projected tolerances are used to make the tolerance more specific.
Projected tolerances are specified in addition to positional tolerances to make
the tolerance more specific. For example, projected tolerances control the
perpendicularity tolerance zone of an embedded part.
The symbol for projected tolerance ( ) is preceded by a height value, which
specifies the minimum projected tolerance zone. The projected tolerance zone
height and symbol appear in a frame below the feature control frame, as shown
in the following illustration.
Composite Tolerances
A composite tolerance specifies two tolerances for the same geometric
characteristic of a feature or for features that have different datum
requirements. One tolerance relates to a pattern of features and the other
tolerance to each feature within the pattern. The individual feature tolerance
is more restrictive than the pattern tolerance.
In the following illustration, the point where datums A and B intersect is called
the datum axis, the point from which the position of the pattern is calculated.
A composite tolerance could specify both the diameter of the pattern of holes
and the diameter of each individual hole, as in the following illustration.
Dimensions and Tolerances | 683