Drafting Symbols - G-W Learning

AutoCAD and Its Applications Advanced Reference Material

Drafting Symbols

Symbols provide a "common language" for drafters all over the world. However, symbols can be meaningful only if they are created according to the relevant standards or conventions. This document describes and illustrates common dimensioning, GD&T, architectural, piping, and electrical symbols.

Standard Dimensioning Symbols

The size of dimensioning symbols varies with text size, but it should be consistent with the height of the text. In the following illustration, h = text height.

Standard Dimensioning Symbols

1.5 h

h Diameter Radius

2 h

Spherical Radius

Spherical Diameter

90?

Controlled Radius

h

Places or By

h 2

Symmetrical

h Counterbore

0.6 h Countersink

h

60? Depth (or Deep)

h

Dimension Origin

0.5 h

0.5 h

2 h 30?

Taper

1.5 h

15? h

Slope

h h

0.3 h 1.5 h

Square Shape

Reference

2.5 h 30?

0.3 h

Arc Length

h

All Around h = letter height

1.5 h

0.8 h

Statistical Tolerance

Copyright Goodheart-Willcox Co., Inc. May not be reproduced or posted to a publicly accessible website.

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Geometric Dimensioning and Tolerancing Symbols

You can either create your own library of GD&T symbols, or use one of AutoCAD's GD&T fonts to insert the symbols as text. The following tables show how to construct the symbols.

GD&T Symbol Creation

2 h

Identification letter

Optional shoulder

2 h

h

Any needed height

h

Filled or unfilled 60?

Datum Feature Symbol

Target area size (when used)

Form

Straightness Flatness Circularity

2 h

Datum Target number

Datum target symbol Datum target symbol

without area size

with area size

Datum Target Symbol

60?

Movable Datum Target

Symbol

90?

2 h

Target point Target line Target area

Target Point and Target Area

Cylindricity

Profile Location

Profile of a line Profile of a surface Position Concentricity Symmetry

Orientation

Parallelism Perpendicularity

Runout

Angularity

or

Circular runout

or

Total

runout

Geometric Characteristic Symbols

MMC, maximum material condition or MMB, maximum material boundary

RFS, regardless of feature size (no symbol, RFS is assumed unless otherwise specified)

1.5 h

0.8 h

LMC, least material condition or LMB, least material boundary

Material Condition Symbols

Copyright Goodheart-Willcox Co., Inc. May not be reproduced or posted to a publicly accessible website.

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0.8 h Free State

0.8 h

GD&T Symbol Creation

2X 0.4H

Tangent Plane

3 h

1.5 h

Projected Tolerance Zone

Independency

2.5 h

30?

U nequal l y Disposed Pr ofile

0.6 h

0.8 h

1.5 h

Between

Statistical Tolerance

With a dimension

Combined with conventional tolerance

In the feature control frame Statistical Tolerancing Methods

2 h

2 h

h

Feature Control Frame with Straightness Geometric Characteristic Symbol

h = lettering height

Copyright Goodheart-Willcox Co., Inc. May not be reproduced or posted to a publicly accessible website.

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GD&T Symbol Creation

1.5 h

h

h 2h

60?

Feature Control Frame with Flatness Geometric Characteristic Symbol

1.5 h

h 2h

Feature Control Frame with Circularity Geometric Characteristic Symbol

60?

1.5 h h

h 2h

Feature Control Frame with Cylindricity Geometric Characteristic Symbol

2 h

h

h

Feature Control Frame with Profile of a Line Geometric Characteristic

Symbol and a Datum Reference h = lettering height

Copyright Goodheart-Willcox Co., Inc. May not be reproduced or posted to a publicly accessible website.

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GD&T Symbol Creation

2 h

h

h

Feature Control Frame with Profile of a Surface Geometric Characteristic

Symbol and a Datum Reference

0.6 h

1.5 h

h

2 h

60?

Feature Control Frame with Parallelism Geometric Characteristic

Symbol and a Datum Reference

1.5 h

h

2 h

2 h

Feature Control Frame with Perpendicularity Geometric Characteristic

Symbol and a Datum Reference

30?

h

2 h

1.5 h

Feature Control Frame with Angularity Geometric Characteristic

Symbol and a Datum Reference

h = lettering height

Copyright Goodheart-Willcox Co., Inc. May not be reproduced or posted to a publicly accessible website.

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