Engineering graphics with AutoCAD 2009 9780135000892, 0135000890

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Engineering Graphics with ® AutoCAD 2009

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Engineering Graphics with ® AutoCAD 2009 James D. Bethune Boston University

Upper Saddle River, New Jersey Columbus, Ohio

Library of Congress Control Number: 2008921109

Editor in Chief: Vernon Anthony Acquisitions Editor: Jill Jones-Renger Editorial Assistant: Doug Greive Development Editor: Lisa S. Garboski, bookworks publishing services Project Manager: Louise N. Sette Production Supervision: Lisa S. Garboski, bookworks publishing services Art Director: Diane Ernsberger Cover Designer: Jason Moore Cover Image: James D. Bethune AV Project Manager: Janet Portisch Operations Specialist: Deidra M. Schwartz Director of Marketing: David Gesell Marketing Coordinator: Alicia Dysert This book was set by Aptara, Inc. It was printed and bound by Courier Kendallville, Inc. The cover was printed by Coral Graphic Services, Inc. Certain images and materials contained in this publication were reproduced with the permission of Autodesk, Inc. © 2008. All rights reserved. Autodesk and AutoCAD are registered trademarks of Autodesk, Inc., in the U.S.A. and certain other countries. Disclaimer: The publication is designed to provide tutorial information about AutoCAD® and/or other Autodesk computer programs. Every effort has been made to make this publication complete and as accurate as possible. The reader is expressly cautioned to use any and all precautions necessary, and to take appropriate steps to avoid hazards, when engaging in the activities described herein. Neither the author nor the publisher makes any representations or warranties of any kind, with respect to the materials set forth in this publication, express or implied, including without limitation any warranties of fitness for a particular purpose or merchantability. Nor shall the author or the publisher be liable for any special, consequential or exemplary damages resulting, in whole or in part, directly or indirectly, from the reader’s use of, or reliance upon, this material or subsequent revisions of this material. Copyright © 2009 by Pearson Education, Inc., Upper Saddle River, New Jersey 07458. Pearson Prentice Hall. All rights reserved. Printed in the United States of America. This publication is protected by Copyright and permission should be obtained from the publisher prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or likewise. For information regarding permission(s), write to: Rights and Permissions Department. Pearson Prentice Hall™ is a trademark of Pearson Education, Inc. Pearson® is a registered trademark of Pearson plc Prentice Hall® is a registered trademark of Pearson Education, Inc. Pearson Education Ltd., London Pearson Education Singapore Pte. Ltd. Pearson Education Canada, Inc. Pearson Education—Japan

Pearson Education Malaysia Pte. Ltd. Pearson Education Australia Pty. Limited Pearson Education North Asia Ltd., Hong Kong Pearson Educación de Mexico, S.A. de C.V.

10 9 8 7 6 5 4 3 2 1 ISBN-13: 978-0-13-500089-2 ISBN-10: 0-13-500089-0

Preface

This book teaches technical drawing and uses AutoCAD® as its drawing instrument. This book updates Engineering Graphics with AutoCAD® 2008 for AutoCAD® 2009. It follows the general format of many technical drawing texts and presents much of the same material about drawing conventions and practices, with emphasis on creating accurate, clear drawings. For example, the book shows how to locate dimensions on a drawing so that they completely define the object in accordance with current national standards, but the presentation centers on the Dimension toolbar and its associated tools and options. The standards and conventions are presented and their applications are shown using AutoCAD® 2009. This integrated teaching concept is followed throughout the book. Most chapters include design problems. The problems are varied in scope and are open-ended, which means that there are several correct solutions. This is intended to encourage student creativity and increase their problem-solving abilities. Chapters 1 through 3 cover AutoCAD Draw and Modify toolbars and other commands needed to set up and start drawings. The text starts with simple Line commands and proceeds through geometric constructions. The final sections of Chapter 3 describe how to bisect a line and how to draw a hyperbola, a parabola, a helix, and an ogee curve. Redrawing many of the classic geometric shapes will help students learn how to use the Draw and Modify toolbars, along with other associated commands, with accuracy and creativity.

Chapters 2 and 3 also show how to use the dynamic input options. Chapter 4 presents freehand sketching. Simply stated, there is still an important place for sketching in technical drawing. Many design ideas start as freehand sketches and are then developed on the computer. This chapter now includes extensive exercise problems associated with object orientation. Chapter 5 presents orthographic views. Students are shown how to draw three views of an object using AutoCAD. The discussion includes projection theory, hidden lines, compound lines, oblique surfaces, rounded surfaces, holes, irregular surfaces, castings, and thin-walled objects. The chapter ends with several intersection problems. These problems serve as a good way to pull together orthographic views and projection theory. Several new, more difficult, exercise problems have been added to this edition. Chapter 6 presents sectional views and introduces the Hatch and Gradient commands. The chapter includes multiple, broken-out, and partial sectional views and shows how to draw an S-break for a hollow cylinder. Chapter 7 covers auxiliary views and shows how to use the Snap, Rotate command to create axes aligned with slanted surfaces. Secondary auxiliary views are also discussed. Solid modeling greatly simplifies the determination of the true shape of a line or plane, but a few examples of secondary auxiliary views help students refine their understanding of orthographic views and eventually the application of UCSs.

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PREFACE

Chapter 8 shows how to dimension both two-dimensional shapes and orthographic views. The Dimension command and its associated commands are demonstrated, including how to use the Dimension Styles tool. The commands are presented as needed to create required dimensions. The conventions demonstrated are in compliance with ANSI Y32. Chapter 9 introduces tolerances. First, the chapter shows how to draw dimensions and tolerances using the Dimension and Tolerance commands, among others. The chapter ends with an explanation of fits and shows how to use the tables included in the appendix to determine the maximum and minimum tolerances for matching holes and shafts. Chapter 10 continues the discussion of tolerancing using geometric tolerances and explains how AutoCAD® 2009 can be used to create geometric tolerance symbols directly from dialog boxes. Both profile and positional tolerances are explained. The overall intent of the chapter is to teach students how to make parts fit together. Fixed and floating fastener applications are discussed, and design examples are given for both conditions. Chapter 11 covers how to draw and design using standard fasteners, including bolts, nuts, machine screws, washers, hexagon heads, square heads, setscrews, rivets, and springs. Students are shown how to create wblocks of the individual thread representations and how to use them for different size requirements. Chapter 12 discusses assembly drawings, detail drawings, and parts lists. Instructions for drawing title blocks, tolerance blocks, release blocks, and revision blocks, and for inserting drawing notes, are also included to give students better preparation for industrial practices. Several new exercise problems have been added to the chapter. Chapter 13 presents gears, cams, and bearings. The intent of the chapter is to teach how to design using gears selected from a manufacturer’s catalog. The chapter shows how to select bearings to support gear shafts and how to tolerance holes in support plates to maintain the desired center distances of meshing gears. The chapter also shows how to create a displacement diagram and then draw the appropriate cam profile. Two new assembly problems involving gears have been added. Chapter 14 introduces AutoCAD 3D capabilities. Both parallel (isometric) and the new perspective grids are demonstrated as well as both WCS and UCS coordinate systems. The intent is to learn the fundamentals of 3D drawings before drawing objects. Chapter 15 shows how to draw three-dimensional solid models. It includes examples of both parallel and perspective grids using all the different Visual Style options. The chapter shows how to union primitive shapes to create more complex models. It also shows how to create ortho-

graphic views from those models. Several new, more complex exercise problems have been added. Chapter 16 presents a solid modeling approach to descriptive geometry. For example, a plane is drawn as a solid that is 0.00001 inch thick. AutoCAD®’s solid modeling and other commands are then used to manipulate the plane. The true lengths of lines and shapes of planes, point and plane locations, and properties between lines and planes are discussed. Piercing points and line visibility are also covered. Online Instructor Materials To access supplementary materials online, instructors need to request an instructor access code. Go to www.pearsonhighered.com/inc, where you can register for an instructor access code. Within 48 hours after registering you will receive a confirming e-mail including an instructor access code. Once you have received your code, go to the site and log on for full instructions on downloading the materials you wish to use. Autodesk Learning License Through a recent agreement with AutoCAD publisher Autodesk®, Prentice Hall now offers the option of purchasing Engineering Graphics with AutoCAD 2009 with either a 180-day or a 1-year student software license agreement. This provides adequate time for a student to complete all the activities in this book. The software is functionally identical to the professional license, but is intended for student personal use only. It is not for professional use. Learning licenses may be purchased only by ordering a special textbook package ISBN. Instructors should contact their local Pearson professional and cureer sales representatives. For the name and number of your sales rep, please contact Prentice Hall Faculty Services at 1 (800) 526-0485. ACKNOWLEDGMENTS I would like to thank the following reviewers. Their comments and suggestions were most helpful in creating this edition: Sidi Berri, New York City College of Technology; Kent Eddy, Kettering University; Doug Koch, Southeast Missouri State University; Dennis Maas, James A. Rhodes State College; and Tony Thomas, Amarillo College. Thanks to Jill Jones-Renger, the editor who pulled it all together; to Lisa Garboski; and Barbara Liguori; also thanks to David, Maria, Randy, Lisa, Hannah, Wil, Madison, Jack, Luke, Sam, and Ben for their continued support. A special thanks to Cheryl. James D. Bethune Boston University

Contents

Chapter 1—Getting Started 1-1 1-2 1-3 1-4 1-5 1-6 1-7 1-8 1-9 1-10 1-11 1-12 1-13 1-14

Introduction 2 Toolbars 4 The Command Line Box 7 Command Tools 7 Starting a New Drawing 8 Naming a Drawing 8 Drawing Units 10 Drawing Limits 12 Grid and Snap 14 Sample Problem SP1-1 15 Save and Save As 16 Open 18 Exit 18 Exercise Problems 19

Chapter 2—Fundamentals of 2D Construction 2-1 2-2 2-3

Introduction 23 Line—Random Points 23 Erase 25

2-4 2-5 2-6 2-7 2-8 2-9 2-10 2-11 2-12 2-13 2-14 2-15 2-16 2-17 2-18 2-19 2-20 2-21 2-22 2-23 2-24 2-25 2-26 2-27 2-28 2-29

Line—Snap Points 26 Line—Coordinate Values 27 Line—Dynamic Inputs 27 Construction Line 28 Circle 31 Circle Centerlines 33 Polyline 34 Spline 37 Ellipse 38 Rectangle 40 Polygon 41 Point 42 Text 42 Move 47 Copy 47 Offset 48 Mirror 48 Array 49 Rotate 50 Trim 51 Extend 52 Break 52 Chamfer 53 Fillet 54 Table 54 Exercise Problems 57

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CONTENTS

Chapter 3—More Advanced Commands 3-1 3-2 3-3 3-4 3-5 3-6 3-7 3-8 3-9 3-10 3-11 3-12 3-13 3-14 3-15 3-16 3-17 3-18 3-19 3-20 3-21 3-22 3-23 3-24 3-25 3-26 3-27 3-28 3-29 3-30 3-31 3-32 3-33 3-34 3-35 3-36 3-37 3-38 3-39

Introduction 69 Osnap 69 Osnap—Endpoint 71 Osnap—Snap From 71 Osnap—Midpoint 72 Osnap—Intersection 73 Osnap—Apparent Intersection 73 Osnap—Center 74 Osnap—Quadrant 74 Osnap—Perpendicular 74 Osnap—Tangent 75 Osnap—Nearest 76 Sample Problem SP3-1 76 Sample Problem SP3-2 77 Grips 8 78 Grips—Extend 79 Grips—Move 79 Grips—Rotate 80 Grips—Scale 80 Grips—Mirror 80 Blocks 81 Working with Blocks 83 Wblock 86 Dynamic Blocks 88 Layers 95 Attributes 102 Title Blocks with Attributes 107 Edit Polyline 109 Edit Spline 109 Edit Text 110 Constructing the Bisector of an Angle— Method I 112 Constructing the Bisector of an Angle— Method II 1 112 Constructing an Ogee Curve (S-Curve) with Equal Arcs 113 Constructing a Parabola 113 Constructing a Hyperbola 114 Constructing a Spiral 115 Constructing a Helix 115 Designing Using Shape Parameters 116 Exercise Problems 118

Chapter 4—Sketching 4-1 4-2 4-3

Introduction 137 Establishing Your Own Style 137 Graph Paper 137

4-4 4-5 4-6 4-7 4-8 4-9 4-10 4-11 4-12 4-13 4-14

Pencils 138 Lines 138 Proportions 139 Curves 140 Sample Problem SP4-1 141 Isometric Sketches 142 Sample Problem SP4-2 144 Oblique Sketches 145 Perspective Sketches 146 Working in Different Orientations 148 Exercise Problems 149

Chapter 5—Orthographic Views 5-1 5-2 5-3 5-4 5-5 5-6 5-7 5-8 5-9 5-10 5-11 5-12 5-13 5-14 5-15 5-16 5-17 5-18 5-19 5-20 5-21 5-22 5-23 5-24 5-25 5-26 5-27 5-28 5-29 5-30 5-31 5-32 5-33 5-34 5-35 5-36

Introduction 163 Three Views of an Object 163 Visualization 164 Hidden Lines 166 Hidden Line Conventions 166 Drawing Hidden Lines 167 Precedence of Lines 171 Slanted Surfaces 171 Projection between Views 172 Sample Problem SP5-1 172 Compound Lines 173 Sample Problem SP5-2 174 Oblique Surfaces 175 Sample Problems SP5-3 176 Rounded Surfaces 177 Sample Problem SP5-4 178 Holes 178 Holes in Slanted Surfaces 181 Cylinders 183 Sample Problem SP5-5 184 Cylinders with Slanted and Rounded Surfaces 185 Sample Problem SP5-6 186 Drawing Conventions and Cylinders 187 Irregular Surfaces 188 Sample Problem SP5-7 188 Hole Callouts 191 Castings 192 Sample Problem SP5-8 194 Thin-Walled Objects 195 Sample Problem SP5-9 196 Intersections 197 Sample Problem SP5-10 197 Sample Problem SP5-11 199 Sample Problem SP5-12 199 Designing by Modifying an Existing Part 202 Exercise Problems 204

CONTENTS

Chapter 6—Sectional Views 6-1 6-2 6-3 6-4 6-5 6-6 6-7 6-8 6-9 6-10 6-11 6-12 6-13 6-14 6-15 6-16 6-17 6-18

Introduction 235 Cutting Plane Lines 237 Section Lines 240 Hatch 241 Sample Problem SP6-1 243 Styles of Section Lines 244 Sectional View Location 244 Holes in Sections 245 Gradients 246 Offset Sections 247 Multiple Sections 248 Aligned Sections 248 Drawing Conventions in Sections 248 Half, Partial, and Broken-out Sectional Views 249 Removed Sectional Views 250 Breaks 250 Sectional Views of Castings 252 Exercise Problems 254

Chapter 7—Auxiliary Views 7-1 7-2 7-3 7-4 7-5 7-6 7-7 7-8 7-9 7-10 7-11 7-12 7-13 7-14 7-15 7-16 7-17

Introduction 269 Projection between Normal and Auxiliary Views 270 Sample Problem SP7-1 272 Transferring Lines between Views 273 Sample Problem SP7-2 275 Projecting Rounded Surfaces 276 Sample Problem SP7-3 276 Projecting Irregular Surfaces 277 Sample Problem SP7-4 277 Sample Problem SP7-5 277 Partial Auxiliary Views 279 Sectional Auxiliary Views 279 Auxiliary Views of Oblique Surfaces 280 Secondary Auxiliary Views 281 Sample Problem SP7-6 284 Secondary Auxiliary View of an Ellipse 285 Exercise Problems 286

Chapter 8—Dimensioning 8-1 8-2 8-3 8-4 8-5

Introduction 302 Terminology and Conventions 302 Linear Dimension 304 Dimension Styles 308 Units 311

8-6 8-7 8-8 8-9 8-10 8-11 8-12 8-13 8-14 8-15 8-16 8-17 8-18 8-19 8-20 8-21 8-22 8-23 8-24 8-25 8-26 8-27 8-28 8-29 8-30 8-31 8-32 8-33 8-34

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Aligned Dimensions 313 Radius and Diameter Dimensions 313 Angular Dimensions 317 Ordinate Dimensions 318 Baseline Dimensions 321 Continue Dimension 322 Quick Dimension 323 Center Mark 324 Quick Leader 324 Dimension Edit 326 Tolerances 328 Dimensioning Holes 328 Placing Dimensions 331 Fillets and Rounds 331 Rounded Shapes (Internal) 331 Rounded Shapes (External) 332 Irregular Surfaces 332 Polar Dimensions 334 Chamfers 334 Knurling 335 Keys and Keyseats 335 Symbols and Abbreviations 336 Symmetry and Centerline 336 Dimensioning to Points 337 Coordinate Dimensions 337 Sectional Views 338 Orthographic Views 338 Very Large Radii 339 Exercise Problems 340

Chapter 9—Tolerancing 9-1 9-2 9-3 9-4 9-5 9-6 9-7 9-8 9-9 9-10 9-11 9-12 9-13 9-14 9-15

Introduction 359 Direct Tolerance Methods 359 Tolerance Expressions 360 Understanding Plus and Minus Tolerances 360 Creating Plus and Minus Tolerances Using AutoCAD 361 Limit Tolerances 363 Creating Limit Tolerances Using AutoCAD 364 Angular Tolerances 365 Standard Tolerances 366 Double Dimensioning 366 Chain Dimensions and Baseline Dimensions 367 Tolerance Studies 369 Rectangular Dimensions 369 Hole Locations 370 Choosing a Shaft for a Toleranced Hole 370

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CONTENTS

9-16 9-17 9-18 9-19 9-20 9-21 9-22 9-23 9-24 9-25 9-26 9-27 9-28

Sample Problem SP9-1 371 Sample Problem SP9-2 372 Standard Fits (Metric Values) 372 Nominal Sizes 374 Hole and Shaft Basis 374 Sample Problem SP9-3 374 Standard Fits (Inch Values) 375 Sample Problem SP9-4 375 Preferred and Standard Sizes 376 Surface Finishes 376 Surface Control Symbols 379 Design Problems 380 Exercise Problems 384

Chapter 10—Geometric Tolerances 10-1 10-2 10-3 10-4 10-5 10-6 10-7 10-8 10-9 10-10 10-11 10-12 10-13 10-14 10-15 10-16 10-17 10-18 10-19 10-20 10-21 10-22 10-23 10-24

Introduction 397 Tolerances of Form 398 Flatness 398 Straightness 398 Straightness (RFS and MMC) 399 Circularity 401 Cylindricity 402 Geometric Tolerances Using AutoCAD 402 Tolerances of Orientation 408 Datums 409 Perpendicularity 410 Parallelism 412 Angularism 412 Profiles 412 Runouts 414 Positional Tolerances 415 Virtual Condition 416 Floating Fasteners 417 Sample Problem SP10-1 418 Sample Problem SP10-2 418 Fixed Fasteners 419 Sample Problem SP10-3 420 Design Problems 421 Exercise Problems 423

Chapter 11—Threads and Fasteners 11-1 11-2 11-3 11-4 11-5 11-6 11-7

Introduction 443 Thread Terminology 443 Thread Callouts (Metric Units) 443 Thread Callouts (English Units) 444 Thread Representations 445 Orthographic Views of Internal Threads 450 Sectional Views of Internal Thread Representations 450

11-8 11-9 11-10 11-11 11-12 11-13 11-14 11-15 11-16 11-17 11-18 11-19 11-20 11-21 11-22 11-23 11-24 11-25 11-26

Types of Threads 451 How to Draw an External Square Thread 452 How to Draw an Internal Square Thread 453 How to Draw an External ACME Thread 453 Bolts and Nuts 455 Screws 455 Studs 455 Head Shapes 456 Nuts 459 Sample Problem SP11-1 462 Sample Problem SP11-2 462 Standard Screws 463 Setscrews 464 Washers 465 Keys 466 Rivets 466 Springs 468 DesignCenter 470 Exercise Problems 474

Chapter 12—Working Drawings 12-1 12-2 12-3 12-4 12-5 12-6 12-7 12-8 12-9 12-10 12-11 12-12 12-13 12-14 12-15 12-16

Introduction 485 Assembly Drawings 486 Drawing Formats (Templates) 488 Title Block 490 Revision Block 492 Tolerance Block 493 Release Block 493 Parts List (Bill of Materials) 494 Detail Drawings 495 First-Angle Projection 496 Drawing Notes 497 Design Layouts 497 Sample Problem SP12-1 498 Sample Problem SP12-2 501 Sample Problem SP12-3 504 Exercise Problems 506

Chapter 13—Gears, Bearings, and Cams 13-1 13-2 13-3 13-4 13-5 13-6 13-7

Introduction 527 Types of Gears 527 Gear Terminology—Spur 527 Spur Gear Drawings 529 Sample Problem SP13-1 530 Sample Problem SP13-2 532 Sample Problem SP13-3 534

CONTENTS

13-8 13-9 13-10 13-11 13-12 13-13 13-14 13-15 13-16 13-17 13-18 13-19 13-20 13-21 13-22 13-23 13-24 13-25

Selecting Spur Gears 534 Center Distance between Gears 534 Sample Problem SP13-4 534 Combining Spur Gears 537 Gear Terminology—Bevel 539 How to Draw Bevel Gears 540 Worm Gears 541 Helical Gears 543 Racks 544 Ball Bearings 545 Sample Problem SP13-5 545 Bushings 547 Sample Problem SP13-6 548 Cam Displacement Diagrams 549 Cam Motions 550 Cam Followers 553 Sample Problem SP13-7 554 Exercise Problems 556

15-9 15-10 15-11 15-12 15-13 15-14 15-15 15-16 15-17 15-18 15-19 15-20 15-21 15-22 15-23

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Revolve 605 Helix 605 Polysolid 605 Loft 606 Intersect 607 Union and Subtract 608 Solid Modeling and UCSs 610 Combining Solid Objects 612 Intersecting Solids 615 Solid Models of Castings 620 Thread Representations in Solid Models 623 List 624 Massprop 625 Face and Edge Editing 625 Exercise Problems 631

Chapter 16—Descriptive Geometry Chapter 14—Fundamentals of 3D Drawing 14-1 14-2 14-3 14-4 14-5 14-6 14-7 14-8 14-9 14-10 14-11 14-12 14-13 14-14 14-15 14-16

Introduction 567 The World Coordinate System 567 Viewpoints 569 Perspective and Parallel Grids 570 3D Modeling 571 User Coordinate Systems (UCS) 573 Editing a Solid Model 575 Creating UCSs on a Perspective Grid 576 Rotating a UCS Axis 576 Sample Problem SP14-1 577 Visual Errors 579 Sample Problem SP14-2 580 Orthographic Views 580 Line Thickness 584 Using the Thickness Command to Create Objects 586 Exercise Problems 589

16-1 16-2 16-3 16-4 16-5 16-6 16-7 16-8 16-9 16-10 16-11 16-12 16-13 16-14

Appendix A-1 A-2 A-3

Chapter 15—Modeling 15-1 15-2 15-3 15-4 15-5 15-6 15-7 15-8

Introduction 595 Box 596 Sphere 598 Cylinder 599 Cone 600 Wedge 601 Torus 603 Extrude 603

Introduction 659 Orthographic Projection 659 The True Length of a Line 662 The True Shape of a Plane 666 Locating a Line in a Plane 670 Locating a Point in a Plane 672 Visibility of a Line 674 Piercing Points 675 Distance between a Line and a Point 679 Distance between Two Lines 681 Angle between a Plane and a Line 682 Angle between Two Planes 684 Intersection 686 Exercise Problems 688

A-4 A-5 A-6 A-7 A-8

Wire and Sheet Metal Gauges 699 American Standard Clearance Locational Fits 700 American Standard Running and Sliding Fits 701 American Standard Transition Locational Fits 702 American Standard Interference Locational Fits 703 American Standard Force and Shrink Fits 703 Preferred Clearance Fits—Cylindrical Fits 704 Preferred Transition and Interference Fits— Cylindrical Fits 705

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CONTENTS

A-9 A-10 A-11 A-12 A-13 A-14 A-15 A-16 A-17 A-18 A-19

A-20 A-21

Preferred Clearance Fits— Cylindrical Fits 706 Preferred Transition and Interference Fits— Cylindrical Fits 707 American National Standard Type A Plain Washers 708 American National Standard Helical Spring Lock Washers 709 American National Standard Internal– External Tooth Lock Washers 709 British Standard Bright Metal Washers— Metric Series 710 American National Standard and Unified Standard Square Bolts 711 American National Standard and Unified Standard Hex Head Screws 712 Coarse-Thread Series, UNC, UNRC, and NC—Basic Dimensions 712 Fine-Thread Series, UNC, UNRC, and NC— Basic Dimensions 713 American National Standard GeneralPurpose Acme Thread Form—Basic Dimensions 714 60° Stub Threads 714 American National Standard Slotted 100° Flat Countersunk Head Machine Screws 715

A-22 A-23 A-24 A-25 A-26 A-27 A-28 A-29 A-30 A-31 A-32 A-33 A-34 A-35 A-36 A-37 A-38

American National Standard Slotted Truss Head Machine Screws 716 American National Standard Plain and Slotted Hexagon Head Machine Screws 717 Slotted Round Head Machine Screws 718 American National Standard Square Head Setscrews 719 American National Standard Square Head Setscrews 720 American National Standard Slotted Headless Setscrews 721 Lengths for Threaded Fasteners 722 Lengths for Metric Threaded Fasteners 722 American National Standard Square and Hexagon Machine Screw Nuts 723 Standard Twist Drill Sizes (Inches) 724 Standard Twist Drill Sizes (Millimeters) 724 Standard Thread Sizes—Inches 725 Metric Threads—Preferred Sizes 725 Thread Lengths 726 Fastness—Standard Lengths 727 American National Standard Plain Washers 728 Flat Washes—Metric Sizes 729

Index 731

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1 Getting Started R

2D Drafting and Annotation

1

2

CHAPTER 1 GETTING STARTED

Large A is the Menu Browser

Click here. Click here.

Figure 1-1

to the right of the heading 2D Drafting & Annotation in the Workspace Control box. See Figure 1-1. A listing of options will cascade down. Click the AutoCAD Classic option. Figure 1-2 shows the AutoCAD Classic format. The third format, 3D modeling, will be introduced in the chapter on 3D modeling. The different formats are intended to make creating a drawing easier. Each format includes commands most often used with the type of drawing being created. The commands function the same way regardless of how they are accessed. For example, the Line command is available in both the 2D Drafting & Annotation and AutoCAD Classic formats. To start a new drawing

1-1 INTRODUCTION The figure on the previous page shows the initial AutoCAD drawing screen. It will appear when the program is first accessed. It shows an AutoCAD screen that uses the 2D Drafting & Annotation format. AutoCAD has three screen formats. To change drawing formats, click the arrow

This section will use the AutoCAD Classic format. Delete the Tool Palettes box by clicking the X in the upper right corner of the box. 1. Click the large A, the Menu Browser, in the upper left corner of the drawing screen to access the command headings box. See Figure 1-2.

Click the large A to access the command headings box. Menu Browser

The AutoCAD Classic screen

Figure 1-2

Click here to delete this tool palette.

GETTING STARTED

3

A listing of command headings will appear. See Figure 1-3. 2. Click the File heading then click the New... command. 1. Click here. Click here.

The Select Template dialog box will appear. See Figure 1-4. 3. Select the acad template by double-clicking the acad option.

The Command Headings box

The 2D AutoCAD screen will appear. See Figure 1-5. The first line is the Standard and Styles toolbars and contains a group of the most commonly used commands. The second line contains the Layers and Properties toolbars. The line above the drawing portion of the screen displays the name of the current drawing. The line reads Drawing2.dwg. Once a drawing name has been defined, it will appear at the top of the screen. The bottom left corner of the drawing screen shows the coordinate display position of the horizontal, vertical crosshairs in terms of an X,Y coordinate value, whose origin is the lower left corner of the drawing screen. The large open area in the center of the screen is called the drawing screen, or drawing editor. The Modify toolbar is located along the right edge of the showing screen. The Draw toolbar has been moved into the drawing area.

Figure 1-3

Double-click here.

Figure 1-4

4

CHAPTER 1 GETTING STARTED

Drawing name

Standard toolbar

Styles toolbar

Layers toolbar

Properties toolbar

Drawing area Cursor

Optional location for the Draw toolbar

Modify toolbar

Origin 0,0 Command line

Figure 1-5

1-2 TOOLBARS An AutoCAD toolbar contains a group of command icons located under a common heading. The initial AutoCAD screen, shown in Figure 1-5, contains six toolbars: Layers, Standard, Properties, Styles, Draw, and Modify. There are 33 additional predefined toolbars, and you can create your own user-specific toolbars as needed. To move a toolbar 1. Locate the cursor arrow on the top of the Modify toolbar in the shaded area that includes a set of small dots. 2. Press and hold down the left mouse button. A light gray broken-line box appears around the edge of the toolbar. 3. Still holding the left mouse button down, move the gray outline box to a new location on the screen.

4. Release the left button. The toolbar will appear in the new location. To change the shape of a toolbar See Figure 1-6. 1. Locate the cursor arrow along the right edge of the Draw toolbar. A double arrow will appear. 2. Press and hold the left mouse button. A light gray broken-line box will appear around the outside of the toolbar. 3. Still holding the left mouse button down, move the mouse around and watch how the gray box changes shape. 4. When the gray toolbar shape is a long, vertical rectangle, release the left mouse button. A reshaped toolbar will appear.

GETTING STARTED

Draw toolbar

To change the shape of a toolbar, locate the cursor arrow along one edge of the toolbar. A double arrow will appear. Press and hold down the left mouse button and move the mouse around. New rectangular shapes will appear. Release the mouse button when the desired shape appears.

5

Modify toolbar

Figure 1-6

To return the toolbar to its original location and shape 1. Locate the cursor arrow along the bottom or edge lines of the toolbar and return the toolbar to its original shape using the procedure outlined in Figure 1-6. 2. Dock the Draw toolbar on the left side of the drawing screen and the Modify toolbar on the right side. To add a new toolbar to the screen See Figures 1-7 and 1-8. 1. Locate the cursor on any one of the existing toolbars and press the right mouse button. In this example the Standard toolbar was selected. A list of the available toolbars will cascade down the screen. 2. Select a new toolbar and click the left mouse button. In this example, the Dimension toolbar was selected. The selected toolbar will appear on the drawing screen. See Figure 1-8. You can move any toolbar or change its shape as described in Figure 1-6.

To remove a toolbar from the screen 1. Locate the cursor arrow on the X located in the upper right corner of the toolbar and press the left mouse button. Note that the close box (the X) is not normally visible. It will appear when the cursor is passed through the right vertical line of the Dimension toolbar. Figure 1-8 shows the Draw and Modify toolbars docked on the left and right sides of the drawing screen. The Dimension toolbar will initially appear within the drawing area of the screen, as will any other toolbar activated. Toolbars can then be moved to different locations, as explained. If the toolbar is located close to either the top or sides of the drawing screen, it will blend into the area surrounding the drawing area and will no longer be within the drawing area. To relocate the toolbars from positions outside the drawing area 1. Locate the cursor arrow above the icons but still below the horizontal line that defines the toolbar area, and press and hold down the left mouse button. A rectangular box will appear around the toolbars that will move with the cursor arrow. Release the left button when the new location is reached.

To access a new toolbar, locate the cursor on an existing toolbar and right-click the mouse. Select the new toolbar and left-click the mouse.

Figure 1-7

The Dimension toolbar

Click and hold here to relocate the toolbar.

Figure 1-8

6

Click here to remove the toolbar. The close box is not normally visible. It will appear when the cursor is passed through the right vertical line of the Dimension toolbar.

GETTING STARTED

7

The Properties toolbar

The Command box expanded to display more command lines

Figure 1-9

1-3 THE COMMAND LINE BOX The size of the Command window, located at the bottom of the screen, may be changed to display more or fewer command lines. It is recommended that at least two command lines be visible at all times. To resize the command line box See Figure 1-9. 1. Locate the cursor arrow along the top edge of the command line box. A double arrow will appear. 2. Still holding the left mouse button down, move the cursor arrow to a new location on the drawing screen. This will move the lower edge of the drawing screen to a new position. 3. Locate the cursor on the top line of the command box.

An equal sign with vertical arrows will appear. 4. Hold the left mouse button down and move the top line of the Command box to align with the lower line of the drawing screen. The Command box will expand to fit the new space. 5. Reverse the process described above to return the Command box and drawing screen to their original sizes. Figure 1-9 also shows the Properties toolbar moved from its original position above the drawing area to a location within the drawing area. AutoCAD allows you to customize the screen to whatever configuration suits your work best.

1-4 COMMAND TOOLS A tool is a picture (icon) that represents an AutoCAD command. Most commands have equivalent tools.

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CHAPTER 1 GETTING STARTED

A toolbar contains tools (icons that allow access to commands).

To determine the command a tool represents, locate the cursor arrow on the tool, but do not press a mouse button. The name of the command represented will appear.

A help box

If you continue to keep the cursor arrow on the tool box, a help box will appear.

Figure 1-10

To determine the command a tool represents See Figure 1-10. 1. Locate the cursor arrow on the selected icon (tool). In the example shown, the Line command tool within the Draw toolbar was selected.

1-6 NAMING A DRAWING Any combination of letters and numbers may be used as a file name. Either upper- or lowercase letters may be used, since AutoCAD file names are not case-sensitive. The symbols $, -, and _ (underscore) may also be used. Other symbols, such as % and *, may not be used. See Figure 1-11.

2. Hold the arrow still without pressing any mouse buttons. The command name will appear below the tool. This name is referred to as a tooltip. If you continue to keep the cursor arrow on the tool box, a help box will appear.

1-5 STARTING A NEW DRAWING When a new drawing is started a drawing name is assigned, the drawing units are specified, the drawing limits are modified, if needed, and Grid and Snap values are defined. The following four sections will show how to start a new drawing.

Figure 1-11

GETTING STARTED

9

Click here to start a new drawing. Click here. Click the large A to access the Command Headings box. Command Headings box

Figure 1-12

All AutoCAD drawing files will automatically have the extension .dwg added to the given file name. If you name a drawing FIRST, it will appear in the files as FIRST.dwg. Other extensions can be used, but the .dwg is the default setting. (A default setting is one that AutoCAD will use unless specifically told to use some other value.) If you want to locate a file on another drive, specify the drive letter followed by a colon in front of the drawing name. For example, in Figure 1-11 the file specified A:FIRST will locate the drawing file FIRST on the A: drive. To start a new drawing There are three ways to access the Create New Drawing dialog box that is used to name a new drawing: 1. Select the New tool from the Command Headings box (see Figure 1-12). 2. Type the word new in response to a command prompt. 3. Hold down the key and press N. Any of these methods will cause the Select template dialog box to appear on the screen. See Figure 1-13. The acad template will set up a drawing using inch values and ANSI style dimensions. The acadiso template will set

up a drawing using millimeter values and ISO style dimensions. To save a new drawing file A drawing name is entered as a file name by using the Save As option located in the Command Headings box. See Figure 1-14. It is recommended that a drawing name be assigned before a new drawing is started. 1. Click the large A in the upper left corner of the screen. 2. Select the Save As tool. The Save Drawing As dialog box will appear. See Figure 1-15. The Save Drawing As dialog box will list all existing drawings. Click on the thumbnail option to change the list to thumbnail drawings. 3. Enter the drawing name. In this example, the drawing name First was used. 4. Select OK. The name of the drawing will appear at the top of the screen. See Figure 1-16.

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CHAPTER 1 GETTING STARTED

This template will set up a drawing with inch values and ANSI style dimensions.

This template will set up a drawing with millimeter values and iso style dimensions.

Figure 1-13

1-7 DRAWING UNITS

Click here.

Click the large A in the upper left corner of the screen to access this box.

AutoCAD 2009’s Select template dialog box allows for either English or metric units to be used as default values; however, AutoCAD can work in any of five different unit systems: Scientific, Decimal, Engineering, Architectural, or Fractional. The default system is the Decimal system and can be applied to either English (inches) or metric values (millimeters). See Figure 1-17. To specify or to change the drawing units

Click here.

1. Select the Format heading in the Command Headings box. 2. Select Units (see Figure 1-18). The Drawing Units dialog box will appear. See Figure 1-19. 3. Select architectural units by clicking the arrow to the right of the Type box. A listing of the five unit options will cascade down. 4. Select Architectural. Note that the Sample Output, located slightly below the center of the Drawing Units box is in fractional inches.

Figure 1-14

GETTING STARTED

Click here to see thumbnail views. Enter drawing name here.

Figure 1-15

Drawing name Five different unit systems

Figure 1-16 5. Repeat the procedure and set the units back to Decimal. To specify or change the precision of the units system Unit values can be expressed with zero to eight decimal places or from 0 to 1/256 of an inch. 1. Access the Drawing Units dialog box as explained previously. 2. Select the arrow to the right of the current precision value display box below the word Precision.

Figure 1-17

11

12

CHAPTER 1 GETTING STARTED

Select degree precision for angles here. Click here.

Select two decimal places.

Click here.

Figure 1-20

Figure 1-18 A listing of the possible decimal precision values will cascade from the box. See Figure 1-20. 3. Select 0.00. The value 0.00 will appear in the Precision box. Select Architectural units.

4. Select OK. The original drawing screen will appear. To specify or change the Angle units value Angles may be specified in one of five different units: Decimal Degrees, Degrees/Minutes/Seconds, Gradians, Radians, or Surveyor units. Decimal Degrees is the default value. Change the angle units by selecting the desired units in the cascade menu under Angle Type. The precision of the angle units is changed as specified for linear units.

See Sample Output.

1-8 DRAWING LIMITS

Figure 1-19

Drawing limits are used to set the boundaries of the drawing. The drawing boundaries are usually set to match the size of a sheet of drawing paper. This means that when the drawing is plotted and a hard copy is made, it will fit on the drawing paper.

GETTING STARTED

13

Click here.

Figure 1-21

Click here.

Figure 1-24

Figure 1-22

A standard 8.5 × 11 letter-size sheet of paper as used by most ink-jet and laser printers is referred to as an A-size sheet of drawing paper. To align the drawing limits with a standard A4 (metric) paper size 1. Click the large A, the Menu Browser, in the upper left corner of the screen, select the New option and create an acadiso template, then again click the large A, select the Format option, then select Drawing Limits. See Figure 1-24. The following prompts will appear in the command line box. Reset Model space limits: Specify lower left corner :

or

[ON/OFF]

Figure 1-23 2. Press the Enter key or the right button on the mouse. Figure 1-21 shows a listing of standard flat-size drawing papers for engineering applications, Figure 1-22 shows standard metric sizes, and Figure 1-23 shows standard architectural sizes.

This means that you have accepted the default value of 0.0000,0.0000, or that the lower left of the drawing screen is the origin of an X,Y axis. Specify upper right corner :

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CHAPTER 1 GETTING STARTED

3. Type 297,210; press Enter. This changes the upper right corner of the drawing screen to an X,Y value of 297,210. There will be no visible change to the screen. The new limit extends beyond the current screen calibration. The screen must be recalibrated to align with the new drawing limits. 4. Type Zoom. Specify corner of window, enter a scale factor (nX or nXP) or [All/Center/Dynamic/Extents/ Previous/Scale/Window] : 5. Type A; press Enter.

Click here.

The Zoom All command will align whatever drawing limits have been defined to the drawing screen. You can verify that the new drawing limits are in place by moving the cursor around the screen and noting the coordinate display box in the lower left corner of the screen. The values should be much larger than they were with the original inch default screen settings. An 8.5 × 11 or A-size sheet size may created by creating an acad template, accessing the Drawing Limits option, and entering upper right corner limits of 11,8.5.

1-9 GRID AND SNAP

Click here.

Figure 1-25

The Grid command is used to place a dotted grid background on the drawing screen. This background grid is helpful for establishing visual reference points for sizing and locating points and lines. The Snap command limits the movement of the cursor to predefined points on the screen. For example, if the Snap command values are set to match the Grid values, the cursor will snap from grid point to grid point. It cannot be located at a point between the grid points. The default Grid and Snap setting for the acad template is 0.50 inch, and the default setting for Grid and Snap for the acadiso template is 10 millimeters.

Click here.

Click here.

Enter new values.

To set the Grid and Snap values 1. Create an acadiso template with AutoCAD Classic format. 2. Access the Format command and select the Drawing Limits option. See Figure 1-25. The Drafting Settings dialog box will appear. See Figure 1-26. If necessary, click the Snap and Grid tab. 3. Click on the Grid On and Snap On boxes. A check mark will appear in the boxes. 4. Place the cursor on the Snap X spacing box to the right of the given value under the Snap On heading. A vertical flashing cursor will appear.

Define the X and Y values for Snap and Grid here.

Figure 1-26 5. Backspace out the existing value and type in 5. 6. Click the Snap Y spacing box. The Y spacing will automatically be made equal to the X spacing value. Nonrectangular snap spacing can be created by specifying different X and Y spacing values.

GETTING STARTED

15

Grid will be applied only to the designated drawing limit area.

To change from icons to words, right-click one of the icons and select use icons.

Snap Grid

Status bar

To turn Grid and Snap on and off, click here, or press F7 for Grid and F9 for Snap.

Figure 1-27

7. Select the Grid X spacing box under the Grid On heading. 8. Backspace out the existing value and type in 10 (just 10). 9. Click the Grid Y spacing box to make the X and Y values equal. 10. Select OK. 11. Type the word zoom, then type A; press Enter. The original drawing screen will appear with a dotted grid. See Figure 1-27. Since the Snap values have been set to exactly half the Grid values, the cursor can be located either directly on grid points or halfway between them. The grid can be turned on and off by either doubleclicking the word GRID at the bottom of the screen or by pressing the key on the keyboard. Snap can be turned on and off by double-clicking the word SNAP at the bottom of the screen or by pressing the key on the keyboard. Grid and Snap can also be activated using the icons on the status bar located at bottom of the screen. See Figure 1-27. The icons may be replaced with words by right-clicking one

of the icons and selecting the Use Icons option. In turn, the icons may be returned by clicking one of the words and again selecting the Use Icons option.

1-10 SAMPLE PROBLEM SP1-1 Set up a drawing that will use millimeter dimensions and the following parameters: Sheet size  297,210 Grid  10 spacing Snap  5 spacing Whole-number precision To specify the drawing units 1. Click the Menu Browser in the upper left corner of the drawing screen and select the File command then the New option.

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CHAPTER 1 GETTING STARTED

Turn on Snap.

Turn on Grid.

Select the acadiso template. Enter values.

Figure 1-28 The Select template dialog box will appear. See Figure 1-28. 2. Select the acadiso template, then Open. To define the drawing precision Figure 1-30 1. Click the Menu Browser in the upper left corner of the drawing screen and select the Format command then the Units option. The Drawing Units dialog box will appear. See Figure 1-29. In this example only whole numbers will be used, so the 0 option is selected. 2. Select the desired precision, then OK.

To calibrate the sheet size 1. Click the Menu Browser in the upper left corner of the drawing screen and select the Format command then the Drawing Limits option. 2. Set the lower limit for 0.0000,0.0000 (accept the default values), and the upper right limit for 297,210. See Section 1-8. The limits are given in terms of their X,Y coordinate values. To set the Grid and Snap values 1. Click the Menu Browser in the upper left corner of the drawing screen and select the Tools command then the Drafting Settings option.

Specify whole-number precision.

The Drafting Settings dialog box will appear. See Figure 1-30. 2. Turn on Grid and Snap and enter the appropriate values. 3. Type the word zoom, then type A; press Enter. The screen is now ready for starting a drawing using millimeter values. Note that the grid fills only the 297 × 210 are a specified as the drawing limits.

1-11 SAVE AND SAVE AS Figure 1-29

The Save and Save As commands are used to save a drawing.

GETTING STARTED

17

Default drive

Default drawing name

Figure 1-31 To use the Save and Save As commands 1. Click the Menu Browser in the upper left corner of the drawing screen and select the File command then the Save or Save As option.

is the default name that was created automatically when a new drawing was created.

The Save As dialog box will appear. See Figure 1-31. In this example the file name Drawing4.dwg appears. This

2. Save the drawing on the C: drive and enter a new file name, Box. See Figure 1-32. 3. Click the Save box.

Specify drive.

Enter new name. Click here.

Figure 1-32

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CHAPTER 1 GETTING STARTED

Drive/file

Click here. Drawing preview

Thumbnails Drawing name

Figure 1-33

1-12 OPEN

See Figure 1-34. The system will exit the AutoCAD program.

The Open command is used to call up an existing drawing so that you may continue working on it, or revise it. To use the Open command The Open command may be accessed in one of two ways: 1. Click the Menu Browser in the upper left corner of the drawing screen and select the File command then the Open option.

Click here.

2. Press  . The Select File dialog box will appear. See Figure 1-33. 3. Click the Views option at the top of the Select File dialog box and click the Thumbnails and Preview options. Thumbnails of the drawing files will appear. 4. Click the desired file A preview will appear. 5. Click the Open box. Click here.

1-13 EXIT The Exit command allows you to exit AutoCAD. 1. Click the Menu Browser in the upper left corner of the drawing screen and select the File command then the Exit option.

Figure 1-34

GETTING STARTED

1-14 EXERCISE PROBLEMS EX1-1 Create a drawing screen as shown. Use the AutoCAD Classic format. Include the Object Snap, Zoom, Draw, Modify, and Dimension toolbars in the orientation and format shown. EX1-2 Create a drawing screen as shown. Use the 2D Drafting & Annotation format, select an acadiso template, and set the Grid spacing for 10 and Snap for 5. Use Zoom all to display the grid across the entire screen. EX1-3 Create a drawing screen as shown. Select an acad 3D template and the AutoCAD Classic format.

Draw

Object Snap

Zoom Modify

Dimension

EX 1-1

19

EX1-4 Create a drawing screen as shown. Use the acad template and the 2D Drafting & Annotation format. Add the following toolbars in the locations shown: Object Snap, Modify II, Zoom, and Text. EX1-5 Create a drawing screen as shown. Use the acad template and the AutoCAD Classic format. Add the following toolbars in the locations shown: Draw, Modify, Dimension, Zoom, USC, Text, and Orbit. EX1-6 Create the following screen setup. Decimal Units Drawing Limits  594,420 Grid  25 Snap  12.5

Grid 10,10 Snap 5, 5

EX 1-2

Origin

EX 1-3

20

Cursor

Format

Object Snap

Modify II

Zoom Text

EX 1-4

Draw Dimension USC

EX 1-5

Orbit

Text

Zoom

Modify

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CHAPTER 1 GETTING STARTED

EX1-7 Create the following screen setup. Architectural Units Drawing Limits  48,36 Grid  6 Snap  3

EX1-8 Create the following screen setup. Fractional Units Drawing Limits  36,24 Grid  1 Snap  1/2

C

2 Fundamentals of 2D Construction H

A

P

2-1 INTRODUCTION

T

E

R

The Draw toolbar Line

This chapter demonstrates how to work with AutoCAD commands. AutoCAD commands are executed by using command tools, toolbars, and a series of prompts. The prompts appear in the command line box and ask for a selection or numeric input so that a command sequence can be completed. The Line command was chosen to demonstrate the various input and prompt sequences that are typical with AutoCAD commands. Most of the commands contained in the Draw and Modify toolbars will be demonstrated in this chapter. The purpose is to present enough commands for the reader to be able to create simple 2D shapes. The next chapter will present more advanced applications for these commands and will present some new commands as well.

Construction Line Polyline Polygon Rectangle Arc Circle

Spline Ellipse

2-2 LINE—RANDOM POINTS

Point

The Line command is used to draw straight lines between two defined points. Figure 2-1 shows the Line tool on the Draw toolbar. There are four ways to define the length and location of a line: randomly select points; set a specific value for the Snap function and select points using the Snap spacing values; enter the coordinate values for the start and end

More of the Draw commands are presented in Chapter 3. Multiline Text

Figure 2-1

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CHAPTER 2 FUNDAMENTALS OF 2D CONSTRUCTION

Select the Enter option to end the Line command sequence. Second point

Line length; the length may be edited by typing in a new value.

Dynamic input

Absolute angle First point Third point

Figure 2-2 points; or use relative inputs and specify the starting point, the length, and the direction of the line. To randomly select points (See Figure 2-2.) 1. Select the Line tool in the Draw toolbar. You can also access the Line command by typing the word line in response to a command prompt. The following command sequence will appear in the command line box. Command: _line Specify first point: 2. Place the cursor randomly on the drawing screen and press the left mouse button. Specify next point or [Undo]:

To exit a command sequence If, as you work, you need to exit a command sequence, press the key, which will return you to a command prompt. The key allows you to exit almost all AutoCAD commands. To create a closed area (See Figure 2-4.) 1. Select the Line tool from the Draw toolbar. Command: _line Specify first point: 2. Select a random point. Specify next point or [Undo]: 3. Select a second random point.

As you move the cursor from point to point dynamic inputs will appear on the screen. See Figure 2-2. Dynamic inputs include an absolute angle and length change box. Dynamic inputs will be discussed in Section 2-6. 3. Randomly pick another point on the screen. Specify next point or [Undo]: AutoCAD will keep asking for another point until you press either the Enter key or the right mouse button. 4. When the right mouse button is pressed a small dialog box will appear. See Figure 2-2. 5. Click the Enter option to end the Line command sequence. The Line command may be reactivated by pressing the right mouse button immediately after selecting the Enter option. A dialog box will appear. See Figure 2-3. Select the Repeat Line option to restart the Line command.

Figure 2-3

FUNDAMENTALS OF 2D CONSTRUCTION

First point

Third point

Erase

Copy

Mirror

Offset

Array

Move

Rotate

Scale

Sketch

Lengthen

Trim

25

Extend

Break

Join

Chamfer

Fillet

Explode

This line was created by typing C in response to the Specify next point or [Close/Undo] prompt. C stands for Close and will join the last point drawn to the first point drawn in the current drawing sequence.

Figure 2-5 Second point

Figure 2-4 Specify next point or [Undo]: 4. Select a third random point. Specify next point or [Close/Undo]: 5. Type c, then press Enter to activate the Close option. A line will be drawn from the third point to the starting point, creating a closed area.

If you change your mind and do not want to erase anything, select the next command you want to use, and the Erase command will be terminated. 2. Select the two open lines by placing the rectangular cursor on each line, one at a time, and pressing the left mouse button. The lines will change color from black to a broken gray pattern. This color change indicates that the line has been selected. The selection is confirmed by a change in the prompt. Select objects: 1 found Select objects: 3. Press the right mouse button or the Enter key to complete the Erase sequence.

2-3 ERASE You can erase any line by using the Erase command. There are two ways to erase lines: select individual lines or window a group of lines. The Erase tool is located on the Modify toolbar. See Figure 2-5. To erase individual lines 1. Select the Erase tool on the Modify toolbar. The following prompt will appear in the command line box. Command: _erase Select objects: The cursor will be replaced by a rectangular cursor. This is the select cursor (pickbox). Any time you see this cursor, AutoCAD expects you to select an entity—in this example, a line. See Figure 2-6.

The two lines should disappear from the screen. To erase a group of lines simultaneously (See Figure 2-6.) 1. Select the Erase tool. Command: _erase Select objects: 2. Place the rectangular select cursor above and to the left of the lines to be erased and press the left mouse button. 3. Move the mouse, and a shaded window will drag from the selected first point. 4. When all the lines to be erased are completely within the window, press the left mouse button. All the lines completely within the window will be selected and will change to broken gray lines. The number of lines selected will be referenced in the command line box.

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CHAPTER 2 FUNDAMENTALS OF 2D CONSTRUCTION

Once selected, elements will change color on the screen.

All elements completely within the window will be erased.

Elements may be erased by selecting them individually or by windowing.

Figure 2-6

5. Press the right mouse button or the Enter key to complete the command sequence. The lines will disappear from the screen. The Undo tool will return all the lines, if needed. If the Erase window was created from right to left, any line even partially within the Erase window would be erased.

Grid points are 0.50 inch apart.

2-4 LINE—SNAP POINTS Lines can be drawn using calibrated Snap spacing. This technique is similar to drawing points randomly, but because the cursor is limited to specific points, the length of lines can be determined accurately. See Figure 2-7. Problem: Draw a 3× 5 rectangle. 1. Set the Grid spacing for .5 and the Snap spacing for .50, and turn both commands on. Zoom the grid to fit the screen. 2. Select the Line tool from the Draw toolbar. Command: _line Specify first point: 3. Select a grid point. Specify next point or [Undo]: 4. Move the cursor horizontally to the right 10 grid spaces and press the left mouse button.

Figure 2-7 The Grid spacing has been set at .5, so 10 spaces equals 5 units. Watch the dynamic input readings as you move the cursor. The X value should increase by 5, and the Y value should stay the same. Specify next point or [Undo]: 5. Move the cursor vertically 6 spaces and press the left mouse button.

FUNDAMENTALS OF 2D CONSTRUCTION

27

4. Move the cursor to the command line and type 8,6; press Enter. Lines can be drawn using coordinate points.

The Y value has been increased 4 inches. Specify next point or [Close/Undo]: 5. Move the cursor to the command line and type 2,6; press Enter. Specify next point or [Close/Undo]: 6. Type c; press Enter. Save or erase the drawing as desired.

2-6 LINE—DYNAMIC INPUTS Dynamic Input allows both angular and distance values to be added to a drawing using screen prompts. Figure 2-8

To create lines using Dynamic Input This example was created using inch values.

Specify next point or [Close/Undo]: 6. Move the cursor horizontally to the left 10 spaces and press the left mouse button. Specify next point or [Close/Undo]: 7. Type c; press Enter. Save or erase the drawing as desired.

2-5 LINE—COORDINATE VALUES AutoCAD will also accept locational inputs, the start and end points of a line, in terms of X,Y coordinate values. The 0,0 origin is located in the lower left corner of the drawing screen. Problem: Draw a 4 × 6 rectangle starting at the 2,2 coordinate point. See Figure 2-8. 1. Select the Line tool from the Draw toolbar. Command: _line Specify first point: 2. Move the cursor to the right of the word point: in the command line and left-click the mouse. Type 2,2; press Enter. Specify next point or [Undo]: 3. Move the cursor to the command line and type 8,2; press Enter. The X value has been increased 6 inches. Specify next point or [Close/Undo]:

1. Click the Line command tool and select a starting point. Figure 2-9 shows the dynamic input for the selected first point. 2. Move the cursor to the approximate location of the second line point. The distance and angular values for this new point will be displayed in boxes. Angular values assume that 0° is a horizontal line to the right of the first line point. 3. Type in the desired distance value. The new value will appear in the distance value box. 4. Continue typing (do not press Enter) and type the < symbol. The line distance will change to the typed value, and the angle box will become active. 5. Type the desired angular value; press Enter. The angular value will be applied to the line, and the Dynamic Input command will prepare for the next line point input. 6. Complete the desired shape; press Enter. To access the Dynamic Input settings See Figure 2-10.

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CHAPTER 2 FUNDAMENTALS OF 2D CONSTRUCTION

After typing in new distance value, type