DOE-HDBK-1016/2-93
Engineering Fabrication,
ENGINEERING FABRICATION, CONSTRUCTION,
Construction, and Architectural Drawings
AND ARCHITECTURAL DRAWINGS
Rev. 0
Page 11
PR-06
Figure 8 Example of Tolerancing
Because tolerances allow a part or the placement of a part or feature to vary or have a range,
all of an object's dimensions can not be specified. This allows the unspecified, and therefor non-
toleranced, dimension to absorb the errors in the critical dimensions. As illustrated in Figure
8 (A) for example, all of the internal dimensions plus each dimension's maximum tolerance adds
up to more than the specified overall dimension and its maximum tolerance. In this case the
length of each step plus its maximum tolerance is 1 1/10 inches, for a maximum object length
of 3 3/10 inches. However the drawing also specifies that the total length of the object cannot
exceed 3 1/10 inches. A drawing dimensioned in this manner is not correct, and one of the
following changes must be made if the part is to be correctly manufactured.
To prevent this type of conflict, the designer must either specify different tolerances for each
of the dimensions so that the length of each smaller dimension plus its maximum error adds up
to a value within the overall dimension plus its tolerance, or leave one of the dimensions off,
as illustrated in Figure 8 (B) (the preferred method).
