Dimensioning Rules
Tolerancing
Rule 10) Every dimension is toleranced.
A toleranced dimension is not a single value, but states the maximum and minimum size that a feature may be and still function correctly. Dimensions that are not toleranced are called basic dimensions.
Rule 11) All dimensions and tolerances apply to the non-deformed part
Cumulative Tolerances (error buildup)
Continuous dimensioning has the disadvantage of accumulating error. It is preferable to use datum dimensioning to reduce error buildup.
What is error build up?
Adding individual dimensions together to get an overall dimension adds the errors associated with each dimension.
e = individual dimension error