FUNDAMENTALS OF TECHNICAL GRAPHICS
FUNDAMENTALS OF TECHNICAL GRAPHICS VOLUME I
EDWARD E. OSAKUE
MOMENTUM PRESS, LLC, NEW YORK
Fundamentals Fundamen tals of Technical Technical Graphics, Graphics, Volume Volume I Copyright © Momentum Press®, LLC, 2018. All rights reserved. No part of this publication may be reproduce reproduced, d, stored in a retrieval system, or transmitted in any form or by any means— electronic, mechanical, photocopy, recording, or any other—except for brief quotations, not to exceed 400 words, without the prior permission of the publisher. First published by Momentum Press ®, LLC 222 East 46th Street, New York, NY 10017 www.momentumpress.net ISBN-13: 978-1-94708-342-4 (print) ISBN-13: 978-1-94708-343-1 (e-book) Momentum Press General Engineering and K-12 Engineering Education Collection Cover and interior design by Exeter Premedia Services Private Ltd., Chennai, India 10 9 8 7 6 5 4 3 2 1 Printed in the United States of America
ABSTRACT
Fundamentals of Technical Graphics Fundamentals Graphics concentrates on the main concepts and principles of technical graphics and provides users with the information they need most in an easy and straightforward manner. The book is divided into two volumes: Volume I contains Chapters 1 to 5, where as Volume II comprises comprise s of Chapters 6 to 10. The chapters chapte rs and topics are organized in a sequence that makes learning a gradual transition from one level to another. However, each chapter is presented in a self-contained self- contained manner and may be studied separately. In each chapter, techniques are presented for implementing the topics treated. Chapter 1 gives the basic information a beginner needs to get started with drafting. Chapter 2 focuses on basic sketching tools and techniques techniques.. Chapter Chapter 3 discusses discusses computer design drafting (CDD) systems and provides relevant information to make the student an informed user of the systems. Chapter 4 covers shape construction, the foundation of creating drawing views. Chapter 5 presents the principles and techniques for creating standard multiview drawings. Chapter 6 discusses auxiliary view creation, whereas Chapter 7 focuses on section view creation. Basic dimensioning is covered in Chapter 8. Isometric pictorials are presented in Chapter 9. Working drawings are covered in Chapter 10, the heart of drafting, and practical information is provided for creating them. The Appendix provides introductory discussions about screw fasteners, general and geometric tolerancing, and surface quality and symbols.
KEYWORDS
auxiliary views, computer design and drafting (CDD), design, dimensionin dimensioning, g, graphics, isometric views, multiview drawings, orthographic projection, section views, shape construction, technical, working drawings
CONTENTS
LIST
OF FIGURES
LIST
OF TABLES
ix xiii xv
PREFACE 1
GUIDELINES
1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 1.10 1.11 2
3
DRAFTING FOR D
Introduction Conventions and Standards Drawing Units Drawing Media Sheet Layout Annotations Linestyles Precedencee of Linestyles Precedenc Applying Linestyles Chapter Review Questions Chapter Exercises
1
1 2 4 5 7 10 14 17 17 18 19
BASIC TECHNICAL SKETCHING
21
2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8
Introduction Sketching Tools Basic Sketching Techniques Sketching Graphic Elements Proportional Sketching Applications of Sketching Chapter Review Questions Chapter Exercises
21 22 29 32 36 38 40 41
COMPUTER D DESIGN DRAFTING SYSTEMS
43
3.1 3.2 3.3
43 44 45
Introduction Brief History of CDD Advantages and Disadvantage Disadvantagess of CDD
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CONTENTS
3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 4
GEOMETRIC
4.1 4.2 4.3 4.4 4.5 4.6 5
CDD System Elements The Desktop Computer Hardware Computer Networks Types of Computer Graphics Some CDD Software Features Creating a CDD Drawing CDD Productivit Productivity y Data Organization and Computer Care Chapter Review Questions Chapter Exercises AND SHAPE CONSTRUCTIONS
Introducti on Introduction Constructing Geometric Elements Constructing Constructi ng Basic Shapes Composition of Compound Shapes Chapter Review Questions Chapter Exercises
STANDARD ORTHOGRAPHIC DRAWING 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 ABOUT INDEX
THE
45 47 51 52 53 56 56 59 60 61 65
65 65 75 81 85 86 91
Introducti on Introduction Projection Types Orthographic Projection Concepts and Assumptions Object Planes and Features Bounding Box Concept Visualizi isualizing ng an Orthographi Orthographicc View Projection Drawing Views Nonunique Views Required Views and Placement Constructing Standard Multiviews Generating Views from Solid Models Checklist for Multiview Drawings Chapter Review Questions Chapter Exercises
91 91 93 94 95 96 97 101 101 103 107 109 109 110
AUTHOR
115 117
LIST
OF FIGURES
Figure 1.1.
Drawing sheet orientations.
7
Figure 1.2.
Sheet layout elements.
8
Figure 1.3.
A simple bill of materials.
9
Figure 1.4.
Vertical characters characters..
11
Figure 1.5.
Inclined characters.
11
Figure 1.6.
Drawing with tolerances
12
Figure 1.7.
Leader, balloon, and callout.
12
Figure 1.8.
Samples of fonts.
13
Figure 1.9.
Linestyles.
15
Figure 1.10. Drawing view with diferent linestyles.
17
Figure 1.11. Use of centerlin centerlinee and center mark.
18
Figure 2.1.
Freehand sketching tools. (a) Wooden pencils. (b) Eraser. (c) Pencil sharpener.
22
Common grid papers. (a) Ortho-gri Ortho-grid d paper. (b) Iso-grid paper.
24
Figure 2.3.
Portable drawing board and T-square.
25
Figure 2.4.
Triangles. (a) 45 Triangle. (b) 60 /30 Triangle.
26
Figure 2.5.
Adjustable triangle.
26
Figure 2.6.
180 Protractor.
26
Figure 2.7.
Compass.
27
Figure 2.8.
Friction divider.
27
Figure 2.9.
Drafting tape roll.
28
Figure 2.2.
°
°
°
°
Figure 2.10. French curve.
28
Figure 2.11. Spline curve.
28
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•
LIST OF FIGURES
Figure 2.12.
Strokes for freehand lettering.
30
Figure 2.13.
Line sketching. (a) Horizontal line. (b) Vertical line. (c) Inclined line
32
Figure 2.14a. Angle sketching with rule of two.
33
Figure 2.14b. Angle sketching with rule of three.
33
Figure 2.15.
Arc sketching.
34
Figure 2.16.
Curve sketching.
35
Figure 2.17.
Circle sketching.
35
Figure 2.18a. Ellipse prolate sketching.
36
Figure 2.18b. Ellipse oblate sketching.
36
Figure 2.19.
Proportional sketching of a single view object using ortho-grid paper. (a) Drawing. (b) Outline proportions. (c) Block the major internal features. (d) Block the minor internal feature. (e) Sketch internal and external features. (f) Finish features and darken visible lines and arcs. 37
Figure 2.20.
Blocking and proportiona proportionall sketching.
38
Figure 2.21.
Gear arm.
38
Figure 2.22.
Form roll lever.
39
Figure 2.23.
Multiview sketch.
39
Figure 2.24.
Multiview sketch.
39
Figure 2.25.
Isometric sketch.
40
Figure 2.26.
Isometric sketch.
40
Figure 3.1.
CDD system elements.
46
Figure 3.2.
Desktop computer system.
48
Figure 3.3.
Laptop computer.
48
Figure 3.4.
Hardcopy processing devices. (a) Printer. (b) Plotter. (c) Scanner.
50
Figure 3.5.
Computer network.
52
Figure 3.6.
Data organization in a computer.
59
Figure P3.1.
Title block.
63
Figure 4.1.
Absolute and polar coordinate techniques. (a) Absolute. (b) Polar.
66
Relative coordinate coordinatess technique. (a) Direct option. (b) ORTHO option.
67
Figure 4.2.
List of figures figures
•
xi
Figure 4.3.
Creating arc from a circle.
69
Figure 4.4.
Creating a llet with the llet tool.
69
Figure 4.5.
Fillet arc tangent to two lines.
71
Figure 4.6.
Fillet arc tangent to a line and another arc.
71
Figure 4.7.
Small llet arc tangent to two arcs.
73
Figure 4.8.
Large llet arc tangent to two arcs.
74
Figure 4.9.
Rectangle by the OR ORTHO THO method. (a) Bottom H-line. (b) Right V-line. V-line. (c) Top Top H-line. (d) Finished rectangle. 76
Figure 4.10.
Rectangle by the oset technique.
77
Figure 4.11.
Circumscribed Circumscri bed hexagon.
78
Figure 4.12.
Inscribed hexagon.
79
Figure 4.13.
Creating a circle.
80
Figure 4.14.
Creating an ellipse.
81
Figure 4.15.
Creating a compound shape. (a) Create a rectangle. (b) Create circles. (c) Create a central H-line. (d) Trim inner circle arcs. (e) Create centerlines. (f) Scale centerline and nish.
82
Figure 4.16a. Arc shape layout.
83
Figure 4.16b. Arc shape.
83
Figure 4.17.
View drawing.
84
Figure 4.18.
Creating a drawing view.
84
Figure 4.19.
Shape layout.
85
Figure 5.1.
Basic types of projection. (a) Parallel projection. (b) Perspective projection.
92
Figure 5.2.
Normal faces.
94
Figure 5.3.
Non-normal faces.
94
Figure 5.4.
Planar and oblique faces.
94
Figure 5.5.
Bounding box and principal dimensions.
95
Figure 5.6.
Image box and object.
97
Figure 5.7.
Object views on principal planes.
97
Figure 5.8.
Image box faces and principal planes.
98
Figure 5.9.
Layout of six principal views on at paper.
98
Figure 5.10.
Spatial and planar quadrants. (a) Spatial layout. (b) Planar layout (Right view).
99
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LIST OF FIGURES
Figure 5.11.
First angle projectio projection. n.
99
Figure 5.12.
Third angle projection.
99
Figure 5.13.
U.S. standard views.
100
Figure 5.14.
European standard views.
100
Figure 5.15.
Principal dimensions and drawing layout. (a) Object principal dimensions. (b) Layout of standard views.
101
Figure 5.16.
Nonunique side views.
102
Figure 5.17.
Placement and alignment of multiview multiviews. s. (a) Correct placement and and alignment.(b) alignment.(b) Top Top view not aligned. aligned. (c) Front view view not aligned.(d) aligned.(d) Right view not aligned. aligned. 103
Figure 5.18a. Object.
104
Figure 5.18b. Bounding box.
104
Figure 5.19.
Front view choice, local axes, and view directions. (a) Front view choice. (b) Axes and view directions directions..
105
View layout. (a) Top and front views’ boundaries. (b) Bounding blocks for views.
106
Development of views. (a) Visible features development. (b) Hidden features development.
106
Figure 5.22.
Completed views.
107
Figure 5.23.
Generated views of a component.
108
Figure 5.24.
Plain multiview drawing.
108
Figure 5.20. Figure 5.21.
LIST
OF
TABLES
Table 1.1. Some ANSI/ASME Y14 standards
3
Table 1.2. Some ISO drawing standards
3
Table 1.3. Drawing units
4
Table 1.4. Standard paper sizes
6
Table 2.1. Freehand and instrument sketching
31
Table 3.1. Generic layers
58
Table 3.2. Linear units for some discipli disciplines nes
59
Table 4.1. Coordinates of points
66
Table 5.1. Principal views and dimensions
101
PREFACE
The technical educational environment has changed dramatically in the last few decades. Instructors and students in design technology, engineering technology, engineering and related disciplines are faced with limited study time but with increasing information for training in technical graphics. Contact hours for lectures and laboratories in technical graphics have been shrinking, but product design continues to grow in complexities and time to market continues to shrink! New design tools, which whi ch are largely computer based, come into the workplace at astonishing speed. There are more materials to cover but in fewer contact hours. These challenges need serious considerations considerations and this book is written to address them. Fundamentals of Technical Graphics is designed for instruction and study with students and instructors of engineering, engineering technology, and design technology in mind. It should be useful to technical consultants, design project managers, Computer Design Drafting (CDD) managers, design supervisors, supervisors , design engineers, and everyone interested in learning the fundamentals of design drafting. The book is written with full cognizancee of current standards of American National Standards Institute/ cognizanc American Society for Mechanical Engineers (ANSI/ASME). The style is plain and and discussions discussions are are straight straight to the the point. point. Its principal principal goal goal is meeting the needs of rst- and second-year students in engineering, engineering technology, design technology, and related disciplines. No assumption is made about the user’s previous knowledge or skills in design drafting. Similarly no one CDD package is discussed. Principles and techniques are presented in generic styles so that users can develop their skills with available CDD package(s). Acquaintance with the computer and basic operating system functionalities may be initially helpful but not required. Basic computer skills such as booting, launching a program, creating folders and subfolders, saving les, and backing up documents are necessary but not required because these skills can be learned easily in a few weeks in a design drafting class.
xvi
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PREFACE
Fundamentals of Technical Graphics concentrates on the main concepts and principles of technical graphics and provides users with the information they need most in an easy and straightforward manner. The book is separated into two volumes: Chapters 1 to 5 are contained in Volume I, while whi le Chapters 6 to 10 are contained con tained in Volume Volume II. The chapters c hapters and topics are organized in a sequence that makes learning a gradual transition from one level to another. However, each chapter is presented in a self-contained self-contained fashion and may be studied separately. In each chapter, techniques are presented for implementing the topics treated. These techniques are largely computer based bas ed but are discussed in such a way that they t hey can be carried out with freehand or instrument sketching. CDD has gradually replaced traditional or board drafting and design, so there appears to be no real need to focus on board drafting skills. Actually, Actually, through freehand sketching, the principles of design drafting can be taught eectively and practice with the computer made easier. This is because the principles of traditional drafting and design are applicable in CDD environmen environments, ts, but the implementation techniques are dierent. Design Graphics Fundamentals is highly condensed so as to maximize the use of production materials. I hope students and teachers, the primary audience, audience, will nd the book a valuable resource and enjoy using it. I am deeply grateful to Momentum Press’ dedicated team of reviewers for their professional critique and invaluable suggestions. Many thanks to the hundreds of students who have taken my drafting courses for their suggestions and critiques over the years. I am profoundly grateful to my wife and children who had to miss me while being busy with my “books”! Please feel free to inform me of any error found and comment(s) for improvement will be highly appreciated. All communications should please be channeled channeled through through the Publisher Publisher.. Edward E. Osakue January, 2018.
CHAPTER 1
GUIDELINES
1.1
FOR DRAFTING
INTRODUCTION
Drafting is the process of creating technical drawings consisting of twodimensionall (2D) images and annotations, and the term draughting is dimensiona is used to describe the language of drafting in this book. Draughting denes the terminology, symbology, conventions, and standards used in drafting. It is the universal technical language that is used for clearly and accurately describing the form, size, nish, and color of a graphic design model for construction or recording. Draughting guidelines deal with standards and conventions in drawing media, lettering, linestyes, projection standards, plot scales, dimensioning rules, sectioning rules, and so on. In this chapter chapter,, we will concentrate mainly on drawing media, lettering, and linestyles, while others will be discussed in the appropriate chapters. The 2D images in drafting are constructed from lines and curves, while annotations are composed from characters. 2D technical drawings may be created using axonometric and perspective principles. Axonometric drawings are 2D drawings obtained by applying orthogonal projection principles to three-dimen three-dimensional sional (3D) objects and include orthograph orthographic, ic, isometric, dimetric, and trimetric drawings. Pictorial drawings such as isometric and perspective drawings mimic 3D objects in appearance, but are made of 2D entities by composition. Most technical drawings are of the orthographic and isometric types, which are the focus of this book. Some standards and conventions apply to both lines and characters in drafting, and they must be learned and used correctly. Therefore, drafting skills involve learning to correctly apply the rules of draughting in creating acceptable or industry standard technical drawings. Prociency in drafting involves being able to create high-quality technical drawings, so becoming procient in drafting must be a commitment executed with determined eort.
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1.2
FUNDAMENTALS OF TECHNICAL GRAPHICS
CONVENTIONS AND ST STANDARDS ANDARDS
Draughting principles, principles, conventions, rules, and standards help to minimize misinterpretations misinterpretatio ns of drawing contents and eliminate errors in the communication of technical ideas. Convention Conventionss are commonly accepted practices, methods, or rules used in technical drawings. Standards are sets of rules established through voluntary agreements that govern the representation of technical drawings. Standards ensure clear communic communication ation of technical ideas. The design drafter must study and understand these conventions convent ions and standards and learn to apply them correctly in practice. For example, good technical drawings are achieved by following some principles such as: 1. Keeping all lines lines black, black, crisp, crisp, and and consistent. consistent. 2. Using dierent linestyles. 3. Ensuring clarity in linestyle dierences such as in thickness or line weight. 4. Ensuring dashes have consistent spacing with denite endpoints. 5. Keeping guide or construction construction lines very very thin. thin. 6. Ensuring that corners are sharp and without overlap in drawing views. 7. Placing dimension with thoughtfulnes thoughtfulnesss and adequate spacing. 8. Making notes simple and concise. 9. Making drawing readabilit readability y a high priority. 10. Ensuring a pleasing drawing layout. Principles one to six are largely built into computer design drafting (CDD) software or packages. This means the CDD operator need not worry about them, except know what linestyle to use for dierent features of objects and assign appropriate line weight or thickness. However, principles 7 to 10 must be mastered and consistently consistent ly applied. These have bearings on accuracy, legibility, neatness, and visual pleasantness of drawings. There are national and international organizations that develop and manage the development of standards. Examples are the American National Standards Institut Institutee (ANSI) and the Internati International onal Standardiza Standardiza-tion Organization (ISO). ANSI is a federation of government, private companies, professional, technical, trade, labor, and consumer organizations that serve as a clearinghou clearinghouse se for nationally coordinated voluntary standards. The standards may deal with dimensions, rating, test methods, safety and performance specications for equipment, products and components, symbols and terminology, and so on. Major contributors
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Table 1.1. Some ANSI/ASME Y14 standards Item
Section
Size and format
Y14.1
Lettering and linestyles
Y14.2
Projections
Y14.3
Pictorial drawings
Y14.4
Dimensioning and tolerancing
Y14.5M
Screw threads
Y14.6
Gears, splines, and serrations
Y14.7
Mechanical assemblies
Y14.14
to ANSI standards include American Society of Mechanical Engineers (ASME), Institute of Electrical and Electronic Engineers (IEEE), American Society for Testing Metals (ASTM), and so on. Drafting standards are specied in ANSI Y14 documents, which give only the characcharac ter of the graphic language. It is to contain 27 or more separate sections when completed. ANSI/ASME Y14.2, Y14.3, and Y14.5M are popular draughting standards in the United States Sample sections of the standard are given Table 1.1. ISO is a nongovernmental worldwide body that coordinates standards development process in virtually every area of human activities. It is located in Switzerland and was founded in 1947. Membership includes over 150 countries, with each country represented by one national standards institution. ANSI is the U.S. representative to ISO. ANSI standards are usually similar but not identical to ISO standards. The design drafter must be diligent in adhering to the standards that are relevant to a particular work. Table 1.2 gives some ISO drawing standards documents. Table 1.2. Some ISO drawing standards Item
Section
Technical drawings: sizes and layout of drawing sheets
ISO 5457
Technical drawings: general principles of presentation
ISO 128
Technical drawings: methods of indicating surface texture
ISO 1302
General tolerances
ISO 2768
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FUNDAMENTALS OF TECHNICAL GRAPHICS
1.3
DRAWING UNITS
All engineering drawings must carry a unit of measure. This is required so that the drawing sizes can be correctly interpreted. Because graphics have linear and angular attributes, the units of length and angles are indispensable in drafting and design.
1.3.1 1.3 .1
UNITS UNI TS OF LENG LENGTH TH
The SI unit of length is the meter. The English or U.S. customary unit of length is the foot (ft). Table 1.3 shows the length denominations for SI and English units. English units are still in use in North America, America, especially in the United States. The SI linear unit for drafting is the millimeter. Mechanical drawings are dimensioned in millimeter (mm). Architectural Architectural drawings may be dimensioned dimensione d in millimeter (mm) and meter (m). Meter and kilometer (km) are used for civil dimensioning. Only decimals are used in metric dimensioning; fractions are not allowed. For numbers less than 1.0, which must be expressed as decimals, a zero before the decimal marker is preferred. For example, 0.234 is preferred to .234. The period symbol is the decimal marker in this example. In English units, mechanical drawings are dimensioned in decimal inches, architectural drawings are commonly dimensioned in feet (‘), and fractional inches and civil drawings are dimensioned in decimal feet and inches. Drawings in metric units carry a general note such as “all dimensions are in millimeter, unless otherwise stated” or the label “METRIC.”
Table 1.3. Drawing units SI: meter (m)
Customary: Inch (in)-foot (ft)
1 m = 1,000 mm = 103 mm 1 m = 100 cm = 102 cm 1 km = 1,000 m = 103 m
1 in = 16 lines 1 ft = 12 inches 1 in = 25.4 mm
1.3.2 1.3 .2
UNITS UNI TS OF ANGL ANGLE E
Angle refers to the relative orientation of lines on a plane or the relative orientation of planes in space and is measured in degrees (o) or radians. There are 360 degrees in a circle; 60 minutes in a degree; and 60 seconds
Guidelines for draftinG
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5
in a minute. The radian is the SI unit of angular measure. One radian is approximately 57.3°. However, the degree is the unit of angular measure in technical drawings.
1.4
DRAWING MEDIA
Drawing media are physical materials that can retain graphic and textual information for a reasonable time period when placed on their surfaces. They are used to produce hard or paper copies of models and drawings. Certain characteristics make these media suitable for drawings and include smoothness, eraseability, dimensional stability, transparency, durability, and cost. Smoothness describes the ease of the media to accept lines and letters without excessive eort. Eraseability describes the ease of the media to allow lines and letters to be erased and cleaned-up. Ghosting is a term used to describe the mark left after lines are erased. The more visible they are, the poorer the eraseability. Dimensional stability refers to the ability of the media to retain size in varying weather conditions. Transparency allows drawings on one side of the media to be visible on the other side. This used to be an important characteristic in traditional drafting, but photocopying technology and plotter capabilities today make this requirement a noncritical factor. factor. Durability refers to the ability of the media to resist normal usage wear and tear. Wear and tear is ever present because wrinkles develop with usage that renders drawings dicult to read or reproduce. Drawing media include bond stationary, vellum, mylar, grid papers, and tracing papers. Bond statio stationary nary or or plain paper is good for all types of technical drawing. They are made from wood pulp of higher quality than newsprint. However, they have low durability. There are dierent grades of plain paper in the market. The better ones are whiter and smoother. Plain papers should be preferab pref erably ly used for sket sketches ches,, explo explorato ratory ry desi design gn draw drawings ings,, and che check ck prin prints. ts. Vellum is Vellum is the most popular drafting paper. It is specially designed to accept pencil marks and ink. It has good smoothness and transparency, but susceptible to humidity and other weather conditions. This makes it not to be very stable stable dimensionally dimensionally.. Some brands brands have better better eraseability. eraseability. Mylar is is a plastic type (polyester) drafting material that has excellent dimensional stability, eraseability, durability, and transparency. It takes ink easily, but it is expensive and requires special polyester lead for drawing on it. It is, thus, used for very high-quality jobs or when cost is not a factor. Mylar may have single or double working (mat) surfaces. The single mat surface is more common.
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FUNDAMENTALS OF TECHNICAL GRAPHICS
Tracing paper is a translucent medium that is good when the need to reduce manual repetitive work is considerable. It can also be used to obtain a nal sketch if the original sketch was drawn on a grid paper. The grid background is not traced in this case. Tracing is a fast and accurate method of reproducing an existing drawing manually. Grid papers papers are especially helpful for good alignment and proportioning of features on drawings when sketching. Advantage should be taken of them whenever available. The square grid is used for sketching orthographic views, and isometric grid is used for sketching isometric views. These grid papers are very common.
1.4.1 1.4 .1
DRAWING DRAW ING SHEET OR PAPER SIZES
Paper or sheet sizes have been standardized by ANSI and ISO. Standard drafting papers are available in sheet or roll form. Table 1.4 summarizes the standard paper or sheet sizes for English (ANSI) and metric (ISO) applications with metric as preferred units. The sizes are the overall dimensions of the sheets without allowance for margins. Roll sheets come in dierent widths and lengths with the width usually equal to one of the standard sheet dimensions as shown in Table 1.4. Metric roll sizes vary from 297 to 420 mm in width. Large metric sheet sizes are cut from metric rolls. Roll sizes in English unit vary in width from 18” to 48”, and the usual length of a roll is 100’ long. In English unit, large sheet sizes F, G, H, J, and K are cut from rolls. In most situations, the paper size is specied by the company company or stated in a given problem. problem. Table 1.4. Standard paper sizes Metric sizes (mm)
English sizes (inches)
A4
210 × 297
A
8.5 × 11
A3
297 × 420
B
11 × 17
A2
420 × 594
C
17 × 22
A1
594 × 841
D
22 × 34
A0
841 × 1189
E
34 × 44
1.4.2 1.4 .2
SHEET SHEE T ORI ORIENTA ENTATION TION
Standard drawing sheet may be oriented with the long-side horizontal and the short-side vertical as shown in Figure 1.1a. This type of orientation is known as landscape and is generally preferred for sheet sizes B, C, D, and E in English unit or sheet sizes A3, A2, A1, and A0 in metric unit.
Guidelines for draftinG
(a) Landscape
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7
(b) Portrait
Figure 1.1. Drawing sheet orientations.
Occasionally, portrait orientation, as shown in Figure 1.1b, is used, but is largely limited to A-size A-size sheet in English unit and A4-size sheet in metric unit. In this layout, the short length l ength of the sheet is horizontal and the long side is vertical.
1.5
SHEET LA LAYOUT YOUT
Drafting paper layout refers to the arrangement of information on the paper.. Figure 1.2 shows the general layout of a template drawing sheet. paper Broadly, the information in a drawing sheet may be classied into two groups of technical and administrative administrative.. The technical information consists of drawing views and annotations. Annotation depends on the amount of details desired in a drawing and may include dimensions and tolerances, notes, and bill of materials in assembly drawings. The technical information usually takes the greater portion of the drawing sheet. Administrative information on a standard drawing sheet includes title block and revision block information. A margin is provided at the four edges (top, bottom, left, and right) of the sheet and is dened by the border line (not shown in Figure 1.2) that is drawn at some distance from the edge. They provide spaces for ling and handling the sheet. Based on ANSI recommenda tions, top, bottom, and right-side margins are in the range of 12.5 mm (1/2”) to 25 mm (1”), depending on the paper size. The left-side margin is often between 12.5 mm (1/2”) to 40 mm (1–1/2”) to allow for binding of sheets. Drawing views depend on the type of documentation required, and annotation content will vary accordingly.
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FUNDAMENTALS OF TECHNICAL GRAPHICS
1.5.1
ZONING
Zoning is a technique used in large paper sizes to aid in quickly locating information on a drawing. It involves assigning spaced numbers on the top and bottom margins of a sheet and spaced letters on the left and right margins as shown in Figure 1.2. This creates a gri d system on the drafting paper that is similar to that used for reading information on maps. A zone is dened by the intersection of a letter segment and a number segment. As a zone is a very small section of the drawing paper, locating lo cating a piece pie ce of inform information ation in it i t is fast. The hatched ha tched block in Figure 1.2 is for zone B3 zone B3..
Revision block area Views, dimensions, and notes area
Title block area
Figure 1.2. Sheet layout elements.
1.5.2 1.5 .2
TITLE TITL E BLOC BLOCK K
By ANSI standard, a title block should be located on the lower-right corner of the drawing sheet. Though dierent title block designs are used by companies, the information contained in them is fairly general. Most information in a title block includes: 1. Company: name, address, phone number. 2. Project/C Project/Client: lient: project number and title or client’s name and address. 3. Drawing: name or title or number. 4. Personnel: designer, drafter, checker, approver. 5. Scale: ratio of design design and drawing sizes. 6. Date: completion completion date of drawing drawing or project. project. 7. Sheet: size and number (page) of sheets in drawing set. 8. Revisions block: a block for revision notes.
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9
9. General tolerance: tolerance applied to a size when unspecied. 10. Projection type symbol: rst or third angle.
1.5.3 1.5 .3
BILL OF MATERIALS (BOM)
An assembly drawing should have a bill of materials (BOM) or parts list. It is usually a table list of the parts or components in an assembly. Figure 1.3 shows a sample of a simple BOM. By ANSI standard, it should be located located on the lower-right lower-right corner of the drawing sheet. Important Important inforinformation in BOM is part name, item number, part material, quantity, part number, or catalog number for standard parts. The item number is the number assigned to a component in a particular assembly drawing, a form of local identication and can change with dierent assembly drawings. The part number is a xed number assigned to that specic component, a form of company or global identication and should not change for dif dif ferent drawings. Other information like weight and stock size may also be included in the parts list.
Bill of materials Item #
Name
Oty
1
Shaft
1
2
Ge a r
1
3
Flange
1
4
Sleeve
1
5
Retainer
1
6
Wood ru key
7
Pulley
1
8
P & W key
1
9
Bearing
2
10
Hex. slotted nut
1
11
Hex. jain nut
1
12
Cotter pin
1
13
S ea l
1
14
Hex. cap screw
4
Figure 1.3. A simple bill of materials.
1.5.4 1.5 .4
REVISION REVI SION BLOC BLOCK K
A revision block is of the same format as a BOM, but tracks changes made on a component or assembly drawing. It is often located on the top
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FUNDAMENTALS OF TECHNICAL GRAPHICS
right-hand corner of the drawing sheet ad indicated in Figure 1.2. Changes on working drawings (prototype and production design drawings) must be approved approved,, so each company usually has a documen documentation tation process in place that must be strictly followed. Preliminary design drawings may be changed without following this process, but with the approval of the engineer or designer. Some of the information items in a revision block may include date, change reason, requester, previous and new sizes, and approved by by..
1.6
ANNOTATIONS
The textual information and symbols added to models and drawing views for complete documentation of design are commonly called annotations. When annotation is done manually, it is called lettering, which whic h used to be a tedious and time-consuming task. But, things are quite dierent now with computers; they have greatly increased the speed and quality of lettering. Text information consists of groups of characters that express meaning, which could be words, phrases, and or sentences. In technical graphics, graphics , the aim is to communicate clearly and legibly so as to avoid misinterpretation misinterpretation of intent and purpose. The factors that can greatly aect legibility are: 1. 2. 3. 4. 5.
1.6. 1. 6.1 1
Font Character size (text height) Character spacing Word spacing Line spacing (leading)
LETTERING CONVENTI CONVENTIONS ONS
Characters have dierent model designs known as fonts. A font is a set or family of character design with specic attributes that determine the print appearance of the characters. The attributes hold the information about the character set. Simpler font styles are easier to read; therefore, open cleancut characters are the best for drafting. ANSI ANSI standard font for lettering in technical graphics is single-stroke Gothic font. Each character in this font is made up of a single straight or curved line element. This makes it easy to draw the characters and make them clear to read. There are uppercase, lowercase, and inclined Gothic letters. However, the vertical Gothic letters have become industry standard. Figure 1.4a shows vertical uppercase letters, Figure 1.4b shows numbers, and Figure 1.4c shows lowercase letters
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A B C D E F G H I J K L M N O P Q R S T U VWX Y Z (a) a b c d e f g h i j k l m n o p q r s t u v w x y z (b) 0123567 89 (c) ertical al charac characters. ters. Figure 1.4. Vertic
A B C DE F G H IJ
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68º
a b c d e fg fg h i j 0123456789 Figure 1.5. Inclined characters.
and proportion, and h o is the symbol for text or character height in the gure. Characters in annotations may be inclined from the horizontal at an angle dened by 5/2 (rise over run), approximately 68 degrees ANSI as shown in Figure 1.5. An important attribute of a font is the text height or font size. Text height is measured in linear unit of mm (inch). The ANSI recommended text height is 3 mm (1/8”). The width of characters varies depending on the specic font. Some characters are narrow like I like I and and others wide like W . The ratio of a character height to the width is described as width factor or aspect ratio. Common aspect ratios for characters are 5/6, 1, and 4/3. The spacing between words should be approximately equal and a minimum of 1/16” (1.5 mm) is recommended. A full character height for word spacing is preferred. The spacing between lines should be at least half the text height, but preferably a full text height. Sentences should be separated by at least one text height; however, if space allows, two text heights should be used. Annotation information may be divided into two categories of technical and administrative information. Administrative information includes revision notes and title block. Revision notes are used for document control and record-keeping of changes in design. The title block contains vital information about the company and the drawing. Technical information includes BOM, dimensions, notes, and specications. Dimensions are the size values of objects, and tolerances are permissible variations on object sizes. The sizes and tolerances shown on drawing views must be the functional or design sizes and tolerances as specied by the engineer or designer. In designer. In Figure 1.6, the diameter size of 20 mm has a tolerance of 0.05 mm. Annotation symbols are commonly used for geometric tolerancing and dimensioning (GD&T). Notes are explanatory or required information needed on models and drawings for proper interpretation. There are two types of notes found in drawings: general and local notes. General notes apply to the whole drawing and may be placed in
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FUNDAMENTALS OF TECHNICAL GRAPHICS
36.87º ± 0.25º
Metric
+0.05 ø20 0
50
30
25±0.05
32.5±0.05 65
Figure 1.6. Drawing with tolerances
ø 25.75 Leader line 2
Balloon
M10×1.5 Callout
M6×1 Callout
Figure 1.7. Leader, balloon, and callout.
the title block or at the bottom of a drawing view area. Local notes apply only to a portion or specic features in a drawing and are placed close to the feature referenced. A leader line can link a local note to a feature or portion of a drawing; callouts callouts and balloons are special formats of placing local notes. Figure 1.7 shows examples of a leader, balloon, and callout. Balloons are local notes placed inside a shape (circle, diamond, etc.). Callouts are local notes placed without a shape. Notes should be made simple and concise. Specications are technical requirements and are usually about material type, processing, and nishing. They often appear as general notes or are put together as separate documents. Leader lines are thin continuous lines used to direct information to specic features in a drawing. A leader line has an arrow head, an inclined segment, and a horizontal segment as a tail. The inclined segment connects the arrow head with the horizontal segment. Annotation in CDD is much easier than lettering. CDD letters are neat, consistent, stylish, and can be created with speed and accuracy.
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Many fonts are available in the CDD software, so there is a tendency to use several fonts in CDD lettering. However, this should be limited, perhaps to two or three. Figure 1.8 shows a sample of fonts. In architectural drawings, Country blueprint and City Blueprint are popular fonts, while Simplex font is popular in mechanical drafting. Placing text in CDD drawings requires decisions on text height and inclination angle at the least. The inclination angle of text is 90 ° by default, but this could be changed. The recommended inclination angle is about 68 °. The position of the text is often selected by clicking with a mouse. Text alignment or justica tion is important in CDD lettering because it aects document appearance and readability. Text can be aligned to the left (left justied), aligned to the center (center justied), or aligned to the right (right justied). Texts that are aligned on both left and right edges are referred to as fully justied. In technical notes, text should be left justied. Character, word, and line spacing have been discussed earlier and in CDD packages; they have default settings that may be changed if desired. Fonts can be formatted by applying dierent treatments like bold, italic italic,, and underline. These are called special eects. They add aesthetics and emphasis to annotations. The plot height of a character is the actual size on a printed sheet and may be small print, normal print, or large print. Normal print is the recommended ANSI text height of 3 mm (0.125”). Normal print is used within the drawing views area and works ne for average-sized sheets such as A4 (A-size) and A3 (B-size). Dimensions, notes, and specications should be printed in normal print or standard height. Small prints are smaller than the normal prints and are used when space is limited. They may vary in height from 1.5 to 2.5 mm. It is often used in revision blocks and part lists or BOM. Plot height in large prints can vary from 5 to 10 mm (0.188” to 0.375”). They are used for headers, view names, titles, labels, and num bers in title blocks. For large-siz large-sized ed sheets, text height of 0.175 to 0.25” (5–6 mm) is common, but may be as high as 0.375 (10 mm). Text height for zone letters and numbers is usually larger than those for dimensions or tolerances. Uncrowded text (high aspect ratio) is easy to read, but needs more space than crowded text (small aspect ratio). Some companies may Font name
Lowercase
Uppercase
Arial
Lettering
LETTERING
Century Gothic
Lettering
LETTERING
Helvetica
Lettering
LETTERING
Impact
Lettering
LETTERING
Simplex
Lettering
LETTERING
Figure 1.8. Samples of fonts.
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FUNDAMENTALS OF TECHNICAL GRAPHICS
prefer crowded crowded text to uncrowded; uncrowded; however however,, clean and and easy-to-read easy-to-read annoannotations should be the goal. It is good practice to nd out what the convenconven tion is in your company and stick to it! The design drafter must choose a plot size size that is legible and comfortable comfortable when hard copies copies are are made. made. Small Small plot sizes tend to be hard on on the eyes and should normally be avoided. In CDD situations, there are two aspects of text height: plot size and screen size. The plot size is the actual text height value on a printed or plotted document. document. ANSI-recom ANSI-recommended mended plot plot size for small sized sized drawings is 3 mm (0.125”). The screen text size in CDD is the text display size on the monitor screen of the computer. This may be dierent from the plot size if a drawing is not full scale in the default workspace of a CDD package. In this case, a screen factor must be applied to the desired plot size for comfortable reading or viewing on the screen. The screen text height is the plot size times the screen factor factor in reduction reduction scaling where where the image image plot size is smaller than the image design size. The screen text size is the plot size divided by the screen factor in enlargement scaling where the image plot size is larger than the image design size. Reduction scaling is common in macro-technology products while enlargement scaling is common in micro- or nano-technology products. The ANSI standard plot or print text height of 3 mm (1/8”) works well with A4-size (metric) or A-size (English) sheet. For other sheet sizes, some adjustment in text height may be necessary necessary for comfortable comfortable reading of of prints.
1.7
LINESTYLES
Linestyle describes the visual appearance of lines on papers and monitor screens. Drafting uses dierent linestyles and symbols to describe object models, especially in describing details of 3D graphics in 2D space. Good line quality is essential for accurate communication of drawings. CDD linestyles are crisp, consistent, clear, and dierent line thickness (or line line-weight) and colors can be assigned to them. Their dashes have consistent spacing and constant width. Figure 1.9 shows some linestyles. There are two fundamental linestyles, namely, continuous (solid) and broken lines. Continuous Continuous lines have no gaps but broken lines do. Continuous line variants include visible (object), construction, extension, and border lines. These lines are distinguished by thickness or width. ANSI recommends recommen ds two line weights of thick and thin, with the thick being twice the line weight of the thin. Thick lines have width greater than 0.3 mm and thin lines have width of 0.3 mm or less. Visible and border lines are thick, while guidelines, construction, and extension lines are thin. Broken lines have visible gaps between consecutive line segments. The length of
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15
Thick line (0.6 mm) Thin line (0.3 mm) Visible line Hidden line Center line
Cutting plane lines
Dimension line Extension line 158.31 Dimension line terminator Short brake Long brake Phantom line Section (hatch) line Stitch (dot) line
Figure 1.9. Linestyles.
dash lines can vary from 3 to 10 mm (1/8”–3/8”), and the gap can vary from 1.5 to 3 mm (1/16”–1/8”). Thickness of lines and length of dashes mentioned here are best for an A-size sheet. Visible (object) lines are thick continuous (solid) lines that repreVisible sent visible edges or outlines of object. Straight edges are formed where two planes intersect. Curved edges arise from curved faces and surfaces. Visible lines should be crisp and black with thickness of 0.40, 0.50, or 0.60 mm, depending and sheet size, but ANSI-recommended thickness of visible line is 0.60 mm. Hidden lines Hidden lines are thin dashed lines representing edges that are within the object or behind some features, and so are not directly seen from a view direction. The edges are known to be physically present in an object. Hidden lines generally have dash length of 3 mm (1/8”) and a gap of 1 mm (1/32”), but can vary with sheet size or drawings. The gap is about
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FUNDAMENTALS OF TECHNICAL GRAPHICS
a quarter of the dash length. Hidden lines should start or end at visible or other hidden lines. No gap is allowed between hidden and visible lines. Centerlines are thin broken lines of alternating long and short strokes separated by a gap. A centerline is used to show and locate centers of circles and arcs and to represent lines of symmetry and paths of motion in objects. Centerlines should cross visible lines with 3 mm or more beyond them. The gap and short stroke are of equal length. The short stroke is about a quarter of the long stroke, which is about 10 mm long. Dimension lines are lines are continuous thin lines used to indicate the value of a dimension. A dimension line has three elements: the dimension value, the terminator, and the stem. The stem is the thin line that ends with the terminators at both ends. The terminator may be arrows (usually lled), slashes, or lled circles. The dimension value may be placed on top of the stem or at a broken portion of the stem. Extension lines lines are are a pair of continuou continuouss thin lines used to establish the extent of a dimension. The extension line references a point on a feature with a small gap (1.5 mm minimum) between the point and the beginning of the extension line. They are used in conjunction with dimension lines and slightly extend beyond the dimension lines about 3 mm. Extension and dimension lines are always perpendicular. Phantom lines are lines are thin dashed lines used to identify alternative positions of moving paths, adjacent positions of related paths, or repetitive details. A phantom line consists of a long dash, two short dashes, and gaps between the dashes. Gaps are about 3 mm long but can vary vary.. Cutting plane lines are lines are used to indicate the position and direction of view for cutting planes placed on an object model to create section views. They are also used to indicate auxiliary view plane and direction. Cutting plane lines are either thick phantom phantom or hidden hidden lines with arrow heads heads that are normal to the main lines. The arrows point in the view directions. The long dash is about ve times the short dash. The short dash and gap are of equal length. Gaps are about 3 mm long but can vary. Section (hatch) Section (hatch) lines are thin inclined lines used to identify a solid material cut through by a section plane. They form a pattern on the section aected. Section assembly drawings often have components of dierent materials in the section plane. The deferent materials are distinguished by using dierent angles for section lines in the section. Section line angles normally vary between 15° and 75°. Break Bre ak lines lines can can be either thin or thick. Long breaks are thin, while short breaks are thick. They are used to show that some portion of an object is left out. A short short break line is used for small areas of interest and allows greater details to be shown. Long break lines are used when space
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needs to be saved in representing very long objects. Usually, the middle portion of the object is broken o or the portion without additional additional infor mation is left out. Stitch lines consist lines consist of a series of dots and are also called dot lines. They may be used as projection lines or guidelines in grid papers used for freehand sketching.
1.8
PRECEDENCE OF LINESTYLES
When lines of dierent styles overlap or coincide in a view, some take precedence. precedenc e. Generally Generally,, lines of thicker thicker weight weight take precedence precedence over others of thinner weight. Visible lines take precedence over all other linestyles. The following order of precedence is generally accepted: visible, hidden, cutting plane, centerline, break line, dimension and extension lines, and hatch line. If more than one linestyles coincide in a view, then the rule of precedencee must be applied. precedenc applied.
1.9
APPLYING APPL YING LINESTYLES
Figure 1.10 shows a drawing view with several linestyles used in its representation. The visible, hidden, and centerline styles are perhaps the most frequently used in drawings. Though CDD has highly simplied linestyle
Phantom line (motion path) Center line A
A
Cutting plane line Visible line
Hidden line
Short break line
Phantom line (object line)
Section (hatch) line Extension line 58, 45
Section A-A
Dimension line
Figure 1.10. Drawing view with dierent linestyles.
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FUNDAMENTALS OF TECHNICAL GRAPHICS
Center line extends beyond visible line
Center marks
Figure 1.11. Use of centerline and center mark.
creation and placements, attention should be paid to the placement of centerlines. This is because when the length of the horizontal and vertical centerlines are unequal over a circle or arc, the center mark for the circle or arc will appear unequal. This does not give a neat appearance in a drawing. One way to x this is to draw the centerlines across the circle or arc diameters. Then, scale the centerlines with a scale factor slightly more than 1.0, say 1.25, 1.3, 1.4, or 1.5. Figure 1.11 shows the use of centerlines and center marks. Note that centerlines must not terminate on visible lines. They should extend beyond visible lines at least 3 mm. The center marks may be used in place of centerlines in circles or arcs of small radii or when overcrowding of line types may be a problem. This is due to concern about drawing clari ty and readability, a top priority in graphic communication. Conventions and standards must be applied to ensure unambiguous communication. Center marks are easy and fast to apply to drawings in CDD systems. Linestyle mistakes used to be quite common with board drafting. However, CDD has largely eliminated these because the coding of the CDD software can implement consistent and accurate line weight, line crossing, and display. But, in freehand and instrument sketches, eorts must be made to avoid these errors.
1.10
CHAPTER REVIEW QUESTIONS
1. Dene the terms draughting and drafting as used in this textbook. 2. Dene the terms conventions and standards.
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3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21.
1.11 1.1 1
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State the principles for the creation of good technical drawings. What are the meanings of the acronyms ANSI and ISO? What ANSI standard deals with drafting? drafting? Which section section of ANSI drafting drafting standard standard is concerned concerned with dimensioning and tolerancing? What measurement measurement units are found or used in drafting? drafting? List the rst three standard paper sizes in metric system. List the rst three standard paper sizes in English system. What are the size specications of A- and A4 sheets? What informati information on is often shown in a title block? Dene zoning as used in drawing sheets. What is annotation? Describe lettering. What are the two fundamental types of linestyles linestyles?? List three examples of each fundamenta fundamentall type of linestyles. linestyles. What are the types types of line line thickness thickness mentioned mentioned in this chapter? chapter? Distinguish between visible visible and hidden linestyles. linestyles. When are they used in drawings? When are phantom lines used in drawings? Where are centerlines used in drawings? Can centerlines end at visible visible lines? When can you replace centerlines with center marks?
CHAPTER EXERCISES
EXERCISE 1 (a) Sketch the following following linestyes: 1. Visible line 2. Hidden line 3. Centerline 4. Phantom line (b) Sketch two circles: one big and the other small. Show centerlines on the big circle and center marks on the small circle.
EXERCISE 2 Use freehand sketching to reproduce Figure 1.10 and Figure 1.11, indicating the linestyles.
INDEX
A
American Society for Testing Metals (ASTM), 3 American Society of Mechanical Engineers (ASME), 3 Angle, unit of, 4–5 Annotations, 10–14 Application software, 46–47 Architectural drawings, 4 Arcs, 68–69 Arc with llet tool, 70 ASME. See American Society of Mechanical Engineers ASTM. See American Society for Testing Metals B
Bill of materials (BOMs), 9 BOMs. See Bill of materials Bond stationary, 5 Bounding box concept, 95–96 Break lines, 16–17 C
CAD. See Computer-aided drafting CDD. See Computer design drafting CD drive and disk, 49 CDD software features coordinate systems, 54–55 drawing aids, 55 drawing templates, 55
drawing units, 54 graphic entities, 55 menus and icons, 54 Centerlines, 16 Circle, 79–80 Circumscribed hexagon, 78–79 Compass, 27 Compound shapes, 81–85 Computer-aided Computer -aided drafting (CAD), 43 Computer care, 60 Computer design drafting (CDD) advantages and disadvantages, 45 computer-aided drafting vs., 43 creating drawing, 56 description of, 2 history of, 44–45 productivity,, 56–59 productivity system elements, 45–47 Computer graphics, 52–53 Computer network, 51–52 Continuous lines, 14 Conventions,, 2 Conventions Coordinate systems, 54–55 Cutting plane lines, 16 D
Data organization, 59–60 Desktop computer hardware CD drive and disk, 49 DVD drive and disk, 49 ash drive and disk, 48
118
Index
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hard copy devices, 49 hard drive and disk, 48 plotter,, 50–51 plotter printer,, 49–50 printer scanner, 51 storage drives and disks, 47–48 Dimension lines, 16 Dividers, 27 Drafting, 1 Drafting tape, 27 Draughting, 1 Drawing aids, 55 Drawing media, 5–7 Drawing sheet, 6 Drawing sheet layout bill of materials, 9 overview of, 7 revision block, 9–10 title block, 8–9 zoning, 8 Drawing templates, 55 Drawing units, 4–5, 54 DVD drive and disk, 49 E
Ellipse, 80–81 Eraser, 23 Extension lines, 16 F
File management, 60 Fillet arc tangent to line and another arc, 70–72 to two lines, 70 Flash drive and disk, 48 Freehand lettering, 29–30 Freehand sketching technique, 30 Freehand sketching tools, 22 G
Generating views, solid models, 107–109 Geometric elements arcs, 68–69 arc with llet tool, 70
llet arc tangent to line and another arc, 70–72 llet arc tangent to two lines, 70 lines, 66–68 parallel lines, 68 points, 66 small llet arc tangent to two arcs, 72–75 Graphic entities, 55 Grid papers, 6 H
Hard copy devices, 49 Hard drive and disk, 48 Hexagon, 77–79 Hidden lines, 15–16 I
IEEE. See Institute of Electrical and Electronic Engineers IGES. See Initial Graphics Exchange Specications Initial Graphics Exchange Specications Specicatio ns (IGES), 52–53 Inscribed hexagon, 79 Institute of Electrical and Electronic Engineers (IEEE), 3 Instrument sketching technique, 31 Instrument sketching tools, 24 Irregular curves, 28 ISO drawing standards, 3 L
Lead pencils, 24–25 Length, unit of, 4 Lettering conventions, 10–14 Lines, 66–68 Linestyles applying, 17–18 precedencee of, 17 precedenc types of, 14–17 M
Mechanical drawings, 4 Mechanical pencils, 24–25
Index • 119
Menus and icons, 54 Mylar, 5
Revision block, 9–10 S
N
Nonuniquee views, 101 Nonuniqu O
Operating system, 47 Orthographic drawing views bounding box box concept, concept, 95–96 nonunique views, 101 object planes and features, 94–95 overview of, 91 principal dimensions dimensions and layout, layout, 100–101 principal views, views, 97–98 projection concepts concepts and assumptions, 93–94 projection standards, standards, 98–100 98–100 projection types, types, 91–93 required views and placement, 101–103 standard views, 100 visualizing, 96–97 P
Paper, 23 Paper size, 6 Parallel lines, 68 Pencil sharpener, 23 Phantom lines, 16 Plotter, 50–51 Points, 66 Portable drawing board, 25 Principal dimensions and layout, 100–101 Principal views, 97–98 Printer, 49–50 Projection standards, 98–100 Proportional sketching, 36–38 Protractors, 26 R
Raster graphics, 53 Rectangles, 75–77
Scanner, 51 Shapes construction circle, 79–80 ellipse, 80–81 hexagon, 77–79 rectangles, 75–77 Sheet orientation, 6–7 Sketching applications of, 38–40 denition of, 21 proportional, 36–38 36–38 technical skills, 21 Sketching angles, 33 Sketching arcs, 34 Sketching circles, 35 Sketching ellipses, 35–36 Sketching graphic elements, 32–36 Sketching irregular curves, 34–35 Sketching lines, 32–33 Sketching techniques freehand lettering, 29–30 freehand sketching, 30 instrument sketching, 31 Sketching tools compass, 27 dividers, 27 drafting tape, 27 eraser, 23 freehand, 22 instrument sketching tools, 24 irregular curves, 28 lead or mechanica mechanicall pencils, 24–25 paper,, 23 paper pencil sharpener sharpener,, 23 portable drawing drawing board, 25 protractors, 26 templates, 28 tracing paper, 24 triangles, 26 T-square, 25
120
Index
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wooden pencils, 22–23 Small llet arc tangent to two arcs, 72–75 Solid modeling, generating views, 107–109 Standard for Exchange of Product Model Data (STEP), 52–53 Standard multiview drawing adding centerlines, 107 checklist, 109 drawing hidden features, 106 drawing visible features, 105–106 envisioning bounding box, 104 front view selection, 104–105 layout drawing, 105 Standards, 2 Standard views, 100 STEP. See Standard for Exchange of Product Model Data Stitch lines, 17 Storage drives and disks, 47–48
Technical sketching skills, 21 Templates, 28 Text style, 57 Title block, 8–9 Tracing paper, 6, 24 Triangles, 26 T-square, 25
T
Z
Technical drawings, principles, 2
Zoning, 8
U
Unit of angle, 4–5 Unit of length, 4 User, 46 V
Vector graphics, 52–53 Vellum, 5 Visible (object) lines, 15 Visualizing orthographic drawing, 96–97 W
Wooden pencils, 22–23
