Lecture 6: Dimension

Question 1

Why are dimensions used?

Answer 1

To ensure only one interpretation is needed to construct a part. To provide accuracy, clearness, completeness, and readability.

Question 2

Dimension

Answer 2

Numerical value that measures the size (with, length, height) of something.

Question 3

Dimension lines

Answer 3

Show the direction and extent of the numerical size of a dimension.

Question 4

Extension lines

Answer 4

Used to extend a surface or
a point beyond the outline of the object so that
a numerical size can be related to that surface.

Question 5

Leaders

Answer 5

Thin lines used to connect a
dimension to a particular area.

Question 6

Aligned format

Answer 6

Text is aligned to the dimension line.

Question 7

Unidirectional format

Answer 7

Text is aligned horizontally.

Question 8

Chain dimensions

Answer 8

Relative dimensions measure one after another

Question 9

Baseline dimensions

Answer 9

All dimensions measured from the same point/line.

Question 10

Dimension rules

Answer 10

1. The same information should not be given in two different ways. Unneeded ones should not be given.
2. Overall dimensions should be outside of smaller dimensions
3. On circular end parts, the center-to-center dimensions should be given instead of an overall dimension.
4. Where possible, place dimensions between views.
5. Always give the diameter of a circle instead of the radius.
6. Always give the radius of an arc instead of it’s diameter.
7. Extension lines should not cross each other or cross dimension lines
   9.Do not dimension to hidden lines. Start dimensioning to the view that shows the shape of the object.
8. Always provide location dimensions for the shapes within an object.
9. Text for dimensioning should be 3mm high.
10. Space between the views should be 38–50mm to provide for dimensions.

Question 11

Architectural dimensions

Answer 11

Exterior walls dimensioned to the outside of the stud, interior walls dimensioned to the center of the wall. Windows and doors are dimensioned to the
opening center.

Question 12

Civil survey dimension

Answer 12

Generally no dimension or extension line with text centered above and below the line. Angles are specified using Survey notation of bearings or azimuth.