Geometric Dimensioning and Tolerancing Chapter 2, Symbols and Abbreviations
Dec 14, 2015
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Introduction
• GDT is a language of symbols
• We will see an overview of the symbols associated with:– Dimensioning Symbols– Geometric Characteristics– Modifying Symbols
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Dimensioning Symbols
Spherical Diameter S Spherical Radius SR
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Dimensioning Symbols
Controlled Radius Tolerance CR Number of Places
A controlled radius has no ‘reversals’, but is a smooth curve within the tolerance zone.
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Dimensioning Symbols
Counterbore/Spotface Countersink
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Dimensioning Symbols
Depth/Deep Dimensions Not to Scale
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Dimensioning Symbols
Conical taper Slope
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Dimensioning Symbols
Square Reference Dimension
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Dimensioning Symbols
Dimension Origin Arc Length
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Dimensioning Symbols
All Around All Over
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Dimensioning Symbols
Chain Line
Used to identify a limited region to be treated differently from the rest of the part.
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Geometric Characteristics
Explained in detail in Chapters 6 and 8.
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Modifying Symbols
Maximum Material ConditionMMC
MMC
Refers to the size of the feature associated with the most material.
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Modifying Symbols
Least Material ConditionLMC
LMC
Refers to the size of the feature associated with the least material.
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Modifying Symbols
Continuous Feature Basic Dimension
Used to describe a theoretically exact size.