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GD&T Tutorial Home GD&T Symbols
CNCCookbook Beginner's Guide to GD&T: Symbols
Geometric Dimensioning and Tolerancing (GD&T) Symbol Quick Reference
Control Type
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Characteristic | Symbol | Notes |
| Form | Flatness |  |
Controls form (shape) of size and non-size features. Datum reference is not allowed |
| Straightness |  |
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| Circularity (Roundness) |  |
Controls form (shape) of size features only. Datum reference is not allowed |
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| Cylindricity |  |
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Orientation No relation between features |
Perpendicularity |  |
Controls orientation (tilt) of surfaces, axes, or median planes for size and non-size features. Datum reference required. Optional: Angularity symbol may be used for all orientation controls. |
| Parallelism |  |
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| Angularity |  |
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Location |
Position |  |
Locates center points, axes and median planes for size features. Can also control orientation. |
| Profile of a Surface |  |
Locates surfaces. Can also be used to control size, form, and orientation basaed on datum reference. |
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| Profile of a Line |  |
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| Runout | Total Runout |  |
Controls surface coaxiality Can also control form and orientation of surfaces |
| Circular Runout |  |
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| Location of derived median points. | Concentricity |  |
Locates derived median points of a feature Not common, consider position, runout, or profile instead |
| Symmetry |  |
Feature Control Frame Modifiers
Symbol |
Modifier |
Notes |
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Free State |
Only applies if part is otherwise restrained. |
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Least Material Condition (LMC) |
Useful to maintain minimum wall thickness |
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Maximum Material Condition (MMC) |
Provides bonus tolerance only for a feature of size |
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Projected Tolerance Zone |
Useful on threaded holes for long studs |
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Regardless of Feature Size (RFS) |
Not part of the 1994 standard |
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Tangent Plane |
Useful for interfaces where form is not required |
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Unilateral |
Appears in the 2009 version and refers to unequal profile distribution |
These symbols are provided as a reference for CNCCookbook's free GD&T Tutorial. To learn what they mean, read on or check the Table of Contents for more information.
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