1. Dimensions should not be duplicated and should only include necessary information to produce or inspect the part. 2. Dimensions should be attached to the view that best shows the contour of the feature and avoid dimensioning hidden lines or features. 3. Dimensions should be located between adjacent views without crossing other lines, and circles are dimensioned by diameter while holes are located by centerlines.

1. Technical DesignTechnical Design
DimensioningDimensioning

2. International Systems of
Representation
Each view is located where it’s
seen from
Each view is projected to the opposite
plane

3. 1. Dimensions should NOT be duplicated, or the same
information given in two different ways.
Incorrect
Incorrect Parallel
location

4. 1-1. Another possibility for aligned dimensions:
Incorrect
Incorrect Serial
location

5. 2. No unnecessary dimensions should be used – only those
needed to produce or inspect the part.
Incorrect

6. 3. Dimensions should be attached to the view that best
shows the contour of the feature to be dimensioned,
usually the front view.
Incorrect
Incorrect

7. 4. Whenever possible, avoid dimensioning to hidden lines
and features.
Incorrect

8. 5. Avoid dimensioning over or through the object.
Incorrect

9. 6. A dimension should be attached to only one view; for
example, extension lines should not connect two views.
Incorrect

10. 7. Whenever possible, locate dimensions between adjacent
views and avoid sending extension lines through object views.
Incorrect

11. Correct dimensioning

12. 8. In general, a circle is dimensioned by its diameter and an
arc by its radius.
Holes are located by their
centerlines, which may
be extended and used as
extension lines

13. 9. Holes should be located and sized in the view that shows
the feature as a circle.
Incorrect

14. 10. Do not cross a dimension line with an extension line,
and avoid crossing dimensions with leader lines.
Incorrect

15. 11. Leader lines point toward the center of the feature, and
should not occur horizontally or vertically.
IncorrectCorrect