xv Contents Chapter 1 Geometric Dimensioning and Tolerancing Essentials. .....................1 Introduction. .......................................................................................................2 Introduction to Dimensioning and Tolerancing Practices. ..........................2 History of Engineering Drawings......................................................................3 Development of GD&T. ....................................................................................6 Benefits of GD&T. ..............................................................................................8 Computer-Aided Design and Drafting (CADD).........................................25 Digital Product Definition Data. ....................................................................30 Computer-Aided Manufacturing (CAM).....................................................30 Chapter 2 Dimensioning and Tolerancing Practices........................................41 Introduction. .....................................................................................................41 Dimensioning and Tolerancing Units. ..........................................................42 Fundamental Dimensioning and Tolerancing Rules. .................................45 Definitions Related to Dimensioning and Tolerancing. .............................47 Tolerancing Fundamentals. ............................................................................50 Single Limits. ....................................................................................................53 Maximum Material Condition (MMC). ........................................................53 Least Material Condition (LMC)....................................................................53 Extreme Form Variation. .................................................................................54 Basic Fits of Mating Parts................................................................................54 Clearance Fit. ....................................................................................................56 Allowance..........................................................................................................56 Clearance...........................................................................................................57 Force Fit. ............................................................................................................58 Chapter 3 Introduction to Symbols and Terms..................................................75 Introduction. .....................................................................................................76 Symbol Format and Size. ................................................................................76 Dimensioning and GD&T Symbols...............................................................77 Dimensioning Symbols. ..................................................................................80 Datum Feature Symbols..................................................................................81 Datum Target Symbols....................................................................................82 Geometric Characteristic Symbols.................................................................84 Material Condition and Material Boundary Symbols. ...............................85 Feature Control Frame (FCF)..........................................................................86 Basic Dimensions. ............................................................................................88 Additional Symbols. ........................................................................................89