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Basically, tolerance represent :

• Direct limits or as

tolerance values applied
directly to a dimension

• Geometric tolerances

• Notes referring to

specific condition

• Plus / minus
Figure 4.25 : Tolerance representing

Figure 4.26 : Tolerance representing

4.9.1 Terms

The important terms used in tolerance are :

Table 4.2 : Tolerance terminology

Nominal size - dimension used to describe the general size usually expressed in
common fractions
Basic size - the theoretical size used as a starting point for the application of
tolerances

Actual size - the measured size of the finished part after machining
Limits - the maximum and minimum sizes shown by the tolerance
dimension