| A | B |
|---|
| Dimension lines | Terminated by arrowheads |
| Dimension lines | Shows the beginning and the end of the measurement |
| Dimension lines | Thin line weight |
| Dimension lines | Should be broken to allow for the numbers to be inserted |
| Dimension lines | minimum of 3/8" away from the object |
| Dimension lines | minimum of 1/4" away from parallel dimension lines |
| Extension lines | 1. Extend the edge of the object |
| Extension lines | Thin line |
| Extension lines | 1/16" gap between the object and the start of the extension line |
| Extension lines | Extend about 1/8" beyond the last dimension line |
| Leaders | Are drawn at an angle (usually 30°, 45°, or 60°). |
| Leaders | have a short (1/8") shoulder |
| Leaders | end with an arrowhead |
| Leaders | should not cross over dimension lines |
| Leaders | Avoid making parallel or perpendicular to visible edges |
| Leaders | extend from the first word or the last word of the note |
| Arrowheads | Can be solid filled or open |
| Arrowheads | 1/8" long |
| Arrowheads | 3 times as long as wide |
| Fractional inches | Used where close tolerances are not important |
| Fractional inches | The fraction bar is horizontal |
| Fractional inches | Omit the inch mark |
| Metric | millimeter is the standard unit of measure |
| Metric | abbreviation for millimeters (mm) is usually omitted |
| Metric | 4. If the value is less than one millimeter, a zero should precede the decimal point |
| Decimal inches | Omit zero before the decimal point for values of less than one |
| Decimal inches | should be rounded to two decimal places |
| Decimal inches | the ANSI standard |
| clarity | number one rule of dimensioning |
| dimensions | placed where the shape is best shown |
| dimensions | Shortest placed closest to the object |
| dimensions | Group and align when possible |
| dimensions | 5. Avoid duplicate and/or unnecessary |
| dimensions | Do not place to coincide with a line of a drawing |
| dimensions | Avoid crowding |
| dimensions | avoid placing inside a view |
| dimensions | Avoid hidden features |
| dimensions | Place between views to which they relate |
| dimension lines | thin and dark |
| dimension lines | contrast noticeably with visible lines |
| dimensions | describe both size and location of features |
| Arcs | Dimension by using the radius |
| Circles | Dimension by using the diameter |
| Circles | symbol precedes the circle size |
| circles | Use a "X" when describing quantity |
