DIMENSIONING

Standard

Apply correct dimensioning procedures

Being able to dimension well requires you to develop three different abilities:

Learn the technique of dimensioning Understand the different line types and

techniques used to show dimensions Learn the placement of dimensions

Can you pick the most logical and practical place to put dimensions with respect to an object?

Learn the choice of dimensions Which dimensions should you show and

which ones should you not show?

Dimension

The numerical value that defines the size, shape, location, surface texture, or geometric characteristic of a feature.

Dimension Line Thin, black line (0.5mm graphite) Ends with an arrowhead

Arrowhead indicates direction and length of a dimension

Gap for dimension is usually near the middle

Distance from the object line is 3/8”

Distance away from other dimension lines is ¼”

Extension Line Thin, black line (0.5mm

graphite) Extends from the point on the

drawing that the dimension refers to

Drawn at right angles to dimension lines

Distance (gap) from object line before the extension line starts is 1/16”

Distance that the line extends past the last arrow is 1/8”

Arrows

Drawn free hand Uniform in size and style Do not vary according to size of

drawing or length of dimension 3 times as long as they are wide 1/8” long Narrow and solid

Lettering

Typically centered on the dimension line

If dimensions are right above one another they are staggered

1/8” tall Fractions are a ¼” tall

Sample Dimensioning Dimension refers to the number.

20

11

23

10

Largest dimension to the outside.

Extension lines may cross

Leave enough room between object and dimension lines.

Group Dimensioning

Dimensions should be placed outside the drawing whenever possible

Extension lines should not cross dimension lines

Stagger Dimension Text

Stagger the dimension text on parallel dimensions

Unidirectional and Aligned Methods Unidirectional: All dimensions are

horizontal Aligned: Dimensions are parallel to

object lines

Principles of Good Dimensioning Each feature of an

object is only dimensioned once

Dimensions should be placed in the most descriptive view of the feature

Dimension lines should be aligned and grouped when possible