Dimension Terminology:

Avoid placing dimensions on the part (inside of the view) See Essentials of Engineering Design Graphics Chapter 4

Avoid dimensioning to hidden features See Essentials of Engineering Design Graphics Chapter 4

Always place dimensions where the characteristic shape is shown in the most descriptive view See Essentials of Engineering Design Graphics Chapter 4

Always dimension holes in their circular view with the Ø Always dimension holes in their circular view with the Ø. Specify special features (hole types) with a note. See Essentials of Engineering Design Graphics Chapter 4

Dimension rounded corners and arc features as radii where they appear in their rounded view. See Essentials of Engineering Design Graphics Chapter 4

Dimension cylinders in their rectangular view with a diameter symbol… See Essentials of Engineering Design Graphics Chapter 4

Keep dimensions between views whenever possible See Essentials of Engineering Design Graphics Chapter 4

Extension lines may cross each other and over other lines on the part, but dimension lines should never be crossed. (Hint no “arrow-headed” lines can cross “arrow-headed” lines) See Essentials of Engineering Design Graphics Chapter 4

The overall dimension should always be given The overall dimension should always be given. It should be placed outside of smaller dimensions and be the farthest from the part. See Essentials of Engineering Design Graphics Chapter 4

Do not duplicate dimensions and avoid using unnecessary or superfluous dimensions See Essentials of Engineering Design Graphics Chapter 4

When all of the dimensions are expressed as inches When all of the dimensions are expressed as inches. DO NOT use inch marks ('') or the abbreviation (.in) See Essentials of Engineering Design Graphics Chapter 4

For metric drawings, omit the use of the millimeter (mm) notation following the numeral, as millimeters are the default units. See Essentials of Engineering Design Graphics Chapter 4

Extend leaders from the first or last word in a note Extend leaders from the first or last word in a note. Point them toward (but not touch) the center of the circular features that they are specifying. See Essentials of Engineering Design Graphics Chapter 4

Place dimensions among the various views to avoid crowding Place dimensions among the various views to avoid crowding. Stagger horizontal dimensions to avoid contact or crowding of the values See Essentials of Engineering Design Graphics Chapter 4

Chamfers: Break away sharp edges and help guide the part into a mating assembly. May be specified with one distance and one angle, or with two distances.

Necks: Necks are used for “O” ring seals, parts turned on lathes, and designed failure points

Knurls: Knurling is a process of rolling patterns onto cylindrical objects to make them easier to grip.

Dimensioning in small places

Repetitive features A combination of dimensioning & notes is used. A number in parenthesis indicates how many are required. The word TYPICAL (or TYP) indicates that all shown are the same.