Pictorial Drawing Section 12.1 Types of Pictorial Drawing Section 12.2 Creating Pictorial Drawings

12 Pictorial Drawing Section 12.1 Types of Pictorial Drawing Section 12.2 Creating Pictorial Drawings

Chapter Objectives • Identify and describe various types of pictorial drawings. • Explain the differences in the three types of axonometric projection. • Make cavalier, normal, and cabinet oblique drawings. • Create one-point and two-point perspective drawings. • Select appropriate isometric sections. • Manipulate 3D models in AutoCAD to achieve isometric, oblique, and perspective views.

Fashion and Function In this store design, Koolhaas has completely opened the storefront to passersby on Rodeo Drive. What else in this photo seems unusual for a store display?

406 Drafting Career

Rem Koolhaas, Architect and Designer

One remarkable feature of the Prada store in Beverly Hills is the absence of a façade. There is neither door nor display window—the entire width of the building is open to Rodeo Drive. Look down as you cross the “air curtain” and you see merchandise in large display cones embedded in the ground. Walk ahead and you climb a large wooden stair ﬁ rst up and then down the far side like a hill. Rem Koolhaas, architect, wants to transform the shopping experience.

Every aspect of shopping here is a new experience for the novice. Dressing rooms have “magic mirrors” that allow you to see front and back at the same time. A touch screen lists your possibilities as you try them on and allows you to browse for alternatives. Later, at home, you can rethink your selections and make ﬁ nal choices by logging on to your virtual garment closet. Everything you tried on is right there for you. Academic Skills and Abilities • Academic skills and abilities • Math and science • Visual orientation • Spatial reasoning • Computer applications • Drafting and drawing Career Pathways Bachelor’s degree programs in architecture often require ﬁ ve years to complete. Helpful high school courses include advanced mathematics, science, and computer-aided design (CAD). All states require architects to be licensed.

Go to glencoe.com for this book’s OLC to learn more about Rem Koolhaas.

407 Arcaid/Alamy 12.1 Types of Pictorial Drawing

Connect Scan for this section’s content vocabulary terms and try to deﬁ ne them using what you already know about them, as well as contextual clues, decoding, or dictionary look-up. Content Vocabulary • isometric drawing • dimetric • picture plane • perspective • isometric axes projection • cavalier oblique drawing • axonometric • trimetric • normal oblique • vanishing point projection projection • cabinet oblique • technical illustration Academic Vocabulary Learning these words while you read this section will also help you in your other subjects and tests. • fundamental • speciﬁ c Graphic Organizer Use a chart like the one below to organize notes about pictorial drawings.

Isometric Oblique Perspective Go to glencoe.com for this book’s OLC for a downloadable Uses Uses Uses version of this graphic organizer.

Drawing

Academic Standards

English Language Arts NCTE National Council of Teachers of English Apply strategies to interpret and evaluate texts (NCTE) NCTM National Council of Teachers of Mathematics Mathematics NSES National Science Representation Select, apply, and translate among mathematical representations to solve Education Standards problems (NCTM)

Science Structure and properties of matter (NSES)

408 Chapter 12 Pictorial Drawing Pictorial Drawings What are the three main types of pictorial drawings?

Pictorial drawing is an essential part of graphic language. It is often used to show exploded views on production and assembly drawings (see Figure 12-1). These views are made to explain the operation of machines and equipment, to illustrate parts lists, and so on. See Figure 12-2. The three distinct categories of pictorial drawings are: Figure 12-1 • isometric • oblique An example of a CAD-generated, exploded-view pictorial drawing • perspective

Each category has variations, but the three fundamental ones are based on how the Isometric Drawing drawings are constructed and how they appear. In an isometric drawing, the object is Each has its own speciﬁ c use and is con- aligned with isometric axes, three axes spaced structed in its own unique way. See Figure at equal angles of 120° (see Figure 12-4A). 12-3 for a single object drawn using various Several vertical and horizontal positions of the pictorial techniques. isometric axes are identiﬁ ed in Figure 12-4B

Figure 12-2 An exploded assembly drawing may be used to illustrate a parts list.

Section 12.1 Types of Pictorial Drawing 409 Figure 12-5 Nonisometric lines TWO-POINT PERSPECTIVE

ISOMETRIC

NONISOMETRIC LINES ARE NOT PARALLEL TO ANY OF THE ISOMETRIC AXES.

ONE-POINT PERSPECTIVE Nonisometric lines do not appear in their true length, so they cannot be measured. OBLIQUE CAVALIER Axonometric Projection Axonometric projection is projection Figure 12-3 that uses three axes at angles to show three Types of pictorial drawings sides of an object. Isometric projection is one OBLIQUE CABINET form of axonometric projection. The other forms are dimetric and trimetric projection. and C. You will learn how to apply them later All three projections are made according to in this chapter. the same process; the difference is in the angle Any line of an object that is parallel to one of projection (see Figure 12-6). In isometric of the isometric axes is called an isometric line. projection, the axes form three equal angles of Lines that are not parallel to any of the isomet- 120° on the plane of projection. Only one scale ric axes are nonisometric lines (see Figure 12-5). is needed for measurements along each axis. An important rule of isometric drawing is: Isometric projections are the easiest type of Measurements can be made only along isometric axonometric projection to make. In dimetric lines. projection, only two of the angles are equal,

AB C 120 VERTICAL HORIZONTAL

120 120

FIRST POSITION SECOND POSITION FIRST POSITION SECOND POSITION REGULAR REGULAR

FIRST POSITION SECOND POSITION FIRST POSITION SECOND POSITION REVERSED REVERSED

Figure 12-4 Standard positions for isometric axes

410 Chapter 12 Pictorial Drawing 120 150 120 Deﬁ ne What does the term isometric 135 120 120 105 105 105 projection mean?

30 30 45 15 15 15

ISOMETRIC DIMETRIC TRIMETRIC Oblique Drawing Figure 12-6 The three types of axonometric projection What is an advantage of oblique drawings over isometric drawings? and two special foreshortened scales are Oblique drawings are plotted in the same needed to make measurements. In trimetric way as isometric drawings; that is, on three projection, all three angles are different, and axes. However, in oblique drawing, two axes three special foreshortened scales are needed. are parallel to the picture plane (the plane

Area of a Triangle Calculate the area of the triangle. The triangle is one of the most common geo- Example 2: metric ﬁ gures used in drafting and through- bh AREA = out industry. Finding the area of any triangle 2 is simple, because the formula is the same in 5" (h) 6 x 5 AREA = every case. 2 30 AREA = 6" (b) 2 The formula for ﬁ nding the AREA = 15 in.2 area of a triangle is: bh RIGHT TRIANGLE A = ___ 2 bh AREA = ___ It can also be stated as: The area of any tri- 2 = × angle equals the product of the base and the AREA 10 6/2 60 AREA = __ altitude to that base, divided by 2. 2 Example 1: AREA = 30 in.2

bh AREA = 2 10 x 6 6" (h) AREA = 2 For help with this math activity, go 60 AREA = 2 to this book’s OLC at glencoe.com

2 and click on Math Handbook. 10" (b) AREA = 30 in.

RIGHT TRIANGLE

Academic Standards

Mathematics

Problem Solving Select, apply, and translate among mathematical representations to solve problems (NCTM)

Section 12.1 Types of Pictorial Drawing 411 C Figure 12-7 ANY D D O ANGLE W H The oblique axes and B W W H oblique drawings H D A OBLIQUE AXES

OBLIQUE DRAWINGS

on which the view is drawn) rather than just A one, as in isometric drawing. These two axes on THIS! which drawings are always plotted always make THIS! right angles with each other (see Figure 12-7). As a result, oblique drawings show an object as B if viewed face on. That is, one side of the object is seen squarely, with no distortion, because it is THIS! parallel to the picture plane. NOT THIS! The methods and rules of isometric drawing NOT THIS! apply to oblique drawing. However, oblique drawing also has some special rules: • Place the object so that the irregular outline or contour faces the front. See Figure 12-8A. Figure 12-8 • Place the object so that the longest dimension is Two special rules for oblique drawings parallel to the picture plane (see Figure 12-8B).

Oblique Projection in this way, but, as with isometric projection, Oblique projection, like isometric projec- it is a good idea to understand the theory tion, is used to show depth (see Figure 12-9). behind it. Depth is shown by projectors, or lines, to rep- Because oblique drawing can show one resent the object’s receding edges. These lines face of an object without distortion, it has a are drawn at an angle other than 90° from the distinct advantage over isometric drawing. It picture plane, to make the receding planes is especially useful for showing objects with visible in the front view. As in isometric draw- irregular outlines. Refer again to Figure 12-8A. ing, lines on these receding planes, that are Figure 12-10 shows several positions for actually parallel to each other are shown as oblique axes. In all cases, two of the axes, AO parallel. Figure 12-9 shows how an oblique and OB, are drawn at right angles. The oblique projection is developed. You probably will axis OC can be at any angle to the right, left, never have to develop an oblique projection up, or down. The best way to draw an object

PICTURE TOP VIEW PLANE 45

Figure 12-9 FRONT VIEW MAY BE ANY Oblique projection ANGLE OTHER THAN 90

412 Chapter 12 Pictorial Drawing is usually at the angle from which it would are known as cavalier oblique. Some draft- normally be viewed. ers use three-quarter size receding length. This is sometimes called normal oblique Types of Oblique Drawings or general oblique. If the receding lines are drawn one-half size, the drawing is cabinet Oblique drawings are classiﬁ ed accord- oblique. See Figure 12-11 for a bookcase ing to the length of the receding lines of an in cavalier, normal, and cabinet drawings. object along the oblique axis. Drawings in Cabinet drawings are so named because they which the receding lines are drawn full length are often used in the furniture industry.

O O B B 60 30 C C A A Explain In an oblique drawing, what relationship do two axes have to the picture plane?

A REVERSED AXES A REVERSED AXES TO LEFT TO RIGHT O B O B Perspective Drawing C C When creating pictorial drawings, what factors that affect appearance do you need C C to consider? 45 O O 30 B B A perspective drawing is a three- A A dimensional representation of an object as it looks to the eye from a particular point (see Figure 12-12). Of all pictorial drawings, perspective drawings look the most like A A photographs. The distinctive feature of these TO RIGHT C C TO LEFT drawings is that in perspective, lines on the B B O O receding planes that are actually parallel are not drawn parallel, as they are in isometric and Figure 12-10 oblique drawing. Instead, they are drawn as if they were converging, or coming together. Positions for oblique axes

D .75D .5D WD WWW

MULTIVIEW CAVALIERNORMAL CABINET

Figure 12-11 Three types of oblique drawings

Section 12.1 Types of Pictorial Drawing 413 drawing. The point at which they meet is the vanishing point. Figure 12-14 also shows how the observer’s eye level affects the perspective view. This eye level can be anywhere on, above, or below the ground. If the object is seen from above, the view is an aerial, or bird’s-eye, view. If the object is seen from Figure 12-12 underneath, the view is a ground, or worm’s- Perspective drawing of a music center eye, view. If the object is seen face on, so that the line of sight is directly on it rather than above or below it, the view is a normal view. The view in Figure 12-13 is a normal view. Deﬁ nition of Terms Figure 12-13 illustrates terms used in per- Types of Perspective Drawings spective drawing. The following deﬁ nitions refer Perspective views can have one, two, or even to the card that appears on the picture plane. more vanishing points. One-point perspective, also called parallel perspective, is a perspective view • visual rays The sight lines from points on the card that converge at the observer’s eye. • picture plane (PP) The plane on which the object (a card in this case) is drawn. • line of sight (LS) The visual ray from the eye perpendicular to the picture plane. GROUND OR • station point (SP) The point from which the WORM'S-EYE VIEW observer is looking at the card.

• horizon line (HL) The line formed where a VP horizontal plane that passes through the NORMAL VIEW observer’s eye meets the picture plane. • ground plane The plane on which the observer stands. • ground line (GL) The line formed where the ground plane meets the picture plane. • center of vision (CV) The point at which the AERIAL OR line of sight pierces the picture plane. BIRD'S-EYE VIEW Figure 12-14 Figure 12-14 shows how the projectors, or receding axes, converge in perspective Types of perspective views

LINE OF CENTER OF PICTURE SIGHT VISION PLANE HORIZON

VISUAL RAYS

Figure 12-13 CARD Some perspective terms EYE

STATION GROUND LINE POINT

414 Chapter 12 Pictorial Drawing Ted Mishima Ted

Figure 12-15 The lines of the sidewalk, roof, and building’s side appear to converge at a single point in the distance.

that has one vanishing point (see Figure 12-15). viewer. In that position, the object appears to Notice that if the lines of the building in Figure be the size indicated by the scale. However, 12-15 were extended, they would converge at a if the object is moved back from the scale to single point. a point twice as far away from the viewer, it Two-point perspective drawings have two looks only half as large. Notice that each time vanishing points. This view is also called the distance is doubled, the object looks only angular perspective, because none of the faces is half as large as before. drawn parallel to the picture plane. The photograph in Figure 12-16 shows a typical two- point perspective. Factors That Aff ect Appearance Two factors affect how an object looks in perspective. The fi rst is its distance from the viewer, and the second is its position, or angle, in relation to the viewer. The Eff ect of Distance The size of an object seems to change as you move toward or away from it. The farther Figure 12-16 from the object you go, the smaller it looks. When a building is viewed at an angle, two sides As you come closer, it seems to become larger. can be seen. The top and ground lines on each Figure 12-17 shows a graphic explanation of side appear to converge toward points. This is the this distance effect. An object is placed against eff ect of two-point perspective. a scale at a normal reading distance from the

Section 12.1 Types of Pictorial Drawing 415 Figure 12-17 ETC. The size of an object 1.00" SQUARE AT appears half as large when FOUR TIMES THE NORMAL READING the distance from the DISTANCE observer doubles. (APPROX 6'–0) A B C D 1.00" SQUARE AT TWICE THE NORMAL READING DISTANCE (APPROX 3'–0) 90 60

1.00" SQUARE AT NORMAL READING DISTANCE (APPROX 18.00") 0

DIRECTION C OF 1 23456 B VIEW A D

DIRECTION The Eff ect of Position OF An object’s shape also seems to change VIEW when it is viewed from different angles. This Figure 12-18 is illustrated in Figure 12-18. If you look at a square from directly in front, the top and bot- The position of the object in relationship to the observer tom edges are parallel. If the square is rotated aff ects its appearance. so that you see it at an angle, these edges seem to converge. The square also appears to grow narrower. This foreshortening occurs because out the shape. It serves a practical purpose, one side of the square is now farther from you. not an artistic one. Technical illustrations range from sketches to rather detailed shaded drawings and may be prepared using board drafting techniques Recall How does an object’s appearance or sophisticated CAD or modeling software. change when a person’s distance from it They may be based on any of the pictorial doubles? methods: isometric, perspective, or oblique. The complete project, parts, or groups of parts may be shown. The views may be exterior, Technical Illustration interior, sectional, cutaway, or phantom. The What techniques are used to manipulate purpose in all cases is to provide a clear and the appearance of technical drawings for easily understood description. aesthetic or other reasons? In addition to pictorials, technical illustrations include graphs, charts, schematics, Generally, technical illustration is fl owcharts, diagrams, and sometimes circuit defi ned as a pictorial drawing that pro- layouts. Dimensions are not generally a part vides technical information using visual of technical illustrations, because they are not methods. Technical illustrations are used working drawings. However, dimensions are to present complex parts and assemblies occasionally added to show the relative posi- graphically, in a way that both professionals tion of parts or to show the adjustment of and the general public can read and under- parts in an assembly. stand. They help people understand both the form (shape) and function of parts in an Uses of Technical Illustration assembly. Technical illustrations must show Technical illustration has an important shapes and relative positions in a clear and place in all areas of engineering and science. accurate way. Shading may be used to bring Technical illustrations form a necessary part

416 Chapter 12 Pictorial Drawing of the technical and service manuals for Choice of Drawing Type machine tools, automobiles, machines, and Most technical illustrations are pictorial line appliances. In technical illustration, pictorial drawings. Therefore, you should have a com- drawings describe parts in terms of both their plete understanding of the various types of pic- form and their function. They can also show torial line drawings and their uses. Usually, any the steps that need to be followed to complete type of pictorial drawing can be used as the basis a product on the assembly line or even to set for a technical illustration. However, some types up an assembly line. are more suitable than others. This is especially Technical illustrations have been used for true if the illustration is to be rendered (shaded). many years in illustrated parts lists, operation Figure 12-20 is a V-block shown in several and service manuals, and process manuals types of pictorial drawing. Notice the differ- (see Figure 12-19). The aircraft and automo- ence in the appearance of each. Isometric is tive industries in particular have found pro- the least natural in appearance. Perspective duction illustrations especially valuable. In is the most natural. This might suggest that many industries, these technical illustrations all technical illustrations should be drawn in are used from the time an item is designed, perspective. This is not necessarily true. While through the many production phases, to com- perspective is more natural than isometric in pletion. The technical illustrations included appearance, it takes more time to produce, in the service, repair, and operation manuals and it is also more difﬁ cult to draw. Thus, it is delivered with the product show the customer often a more costly method to use. how to assemble and operate the product. The shape of the object also helps to determine the type of pictorial drawing to use. Figure 12-21 shows a pipe bracket drawn

List What are the uses of technical illustrations?

7 9 8 10 ISOMETRIC DIMETRIC 6

2 3 1 4 TRIMETRIC OBLIQUE CAVLIER

PART NO. PART NAME NO. REQ'D

1 BASE 1 2 MOVABLE JAW 1 3 MOVABLE JAW PLATE 11 4 MACHINE SCREW 1 5 LOCKING PIN 1 6 HANDLE STOP 11 7 HANDLE 1 OBLIQUE CABINET SINGLE-POINT TWO-POINT 8 CLAMP SCREW 1 (PARALLEL) (ANGULAR) 9 JAW FACE 2 PERSPECTIVE PERSPECTIVE 10 CAP SCREW 2 Figure 12-20 Figure 12-19 A V-block in various types of An illustrated parts list pictorial drawing

Section 12.1 Types of Pictorial Drawing 417 in isometric and oblique. This object can be All exploded views are based on the same drawn easily and quickly in oblique. Also, in process: projecting the parts from the posi- many cases, oblique looks more natural than tions they occupy when put together. Simply isometric for objects of this shape. put, the parts are just pulled apart. Refer to If a pictorial drawing is to be used only in Figure 12-23A for the presentation drawing of a plant, the illustrator usually makes it isomet- a fi shing reel. An exploded illustration of the ric or oblique. These are the quickest and least reel is shown in Figure 12-23B. Note that all costly pictorials to make. If the illustration is parts are easily identifi able in the exploded to be used in a publication such as a journal, view. Flow lines are generally used to show operator’s manual, or technical publication, exactly where each part fi ts into the assembly. dimetric, trimetric, or perspective may be used. Identifi cation Illustrations Exploded Views Pictorial drawings are very useful for identi- Perhaps the easiest way to understand an fying parts. They save time when the parts are exploded view is to separate an object into manufactured or assembled in place. They are its individual parts. In Figure 12-22, three also useful for illustrating operating instruc- views are shown in part A, and a pictorial tion manuals and spare-parts catalogs. view is shown in part B. In part C, an “explo- sion” has projected the various parts away from each other. This illustrates the principle of exploded views. Evaluate What type of pictorial drawing is the most natural, and why do all drawings not use this type?

Identiﬁ cation illustrations are usually pre- sented in exploded views. If the object contains several parts, number them as in Figure 12-23B. In this example, the names of the numbered parts are given in a parts list, a portion of which OBLIQUE ISOMETRIC is shown in Figure 12-23C. If an object consists of only a few parts, identify them by their names Figure 12-21 as in Figure 12-24. The shape of an object helps to determine the most suitable type of pictorial drawing to use.

LETTER HOLDER ORTHOGRAPHIC MULTIVIEW DRAWING ISOMETRIC ASSEMBLY DRAWING EXPLODED ISOMETRIC DRAWING ABC

Figure 12-22 How a view is exploded

418 Chapter 12 Pictorial Drawing Figure 12-23 A ﬁ shing reel (A) with an exploded assembly drawing (B) and partial parts list (C) B

Courtesy of Penn Fishing Tackle Inc. Courtesy of Penn Fishing Tackle A

SHAFT NUT

SPRING WASHER

FLAT WASHER

BUMPER NUT SUPPORT ASSEMBLY

ARM ASSEMBLY PAD

Figure 12-24 An identiﬁ cation illustration with parts labeled

Section 12.1 Types of Pictorial Drawing 419 Rendering • Given the refl ections that appear on inside surfaces, does the object have a bright or Rendering, or surface shading, is a method dull fi nish? of enhancing a solid model so that it looks almost lifelike. It may be used when shapes are Consider these defi nitions as you attempt diffi cult to read or for aesthetic reasons. For to answer the questions: most industrial illustrations, accurate descrip- • Refl ectivity the ability for an object’s surface tions of shapes and positions are more impor- to bounce light back to the viewer. tant than fi ne artistic effects. You can often • Opacity not letting light pass through; not achieve satisfactory results without any ren- transparent or translucent. dering. In general, you should limit rendering • Light source direction from which light is when possible. Render the least amount nec- directed onto an object. essary to defi ne the shapes that are being illus- • Material fi nish the quality of the surface of trated. Rendering takes time and is expensive. an object that renders it bright or dull. In board drafting, materials used to render technical illustrations include screen tints, pen and ink, wash, stipple, felt-tip pen and ink with smudge and edge emphasis. Rendering is done in a very different way in Name List diff erent materials used to render CAD drawings. Items to be rendered are created technical illustrations. as solid models using 3D drawing techniques. These models can then be rendered using the Outline Shading rendering function of the CAD software. How- ever, many top companies now import the mod- Outline shading is a convention, or standard els into high-end, dedicated rendering software. method, used by board drafters. It may be done Figure 12-25 shows an example of a part mechanically or freehand. Sometimes a com- that has been modeled and rendered using bination of both methods is used. The light is a CAD program. generally considered to come from behind and When viewing the rendered object in Figure above the observer’s left shoulder and across 12-25, can you answer the following questions? the object’s diagonal (see Figure 12-26A). In Figure 12-26B, the upper left and top edges • Is the part opaque or transparent? are in the light, so they are drawn with thin • Can you tell from which direction the light lines. The lower right and bottom edges are in source is hitting the object? the shadow. They should be drawn with thick lines. In Figure 12-26C, the edges meeting in

LIGHT SOURCE 1 1 1 1

FRONT 2 2 2 A

BCD Figure 12-25 Figure 12-26 CAD programs and third-party rendering software can be used to render solid models. Light source and light-shaded cubes

420 Chapter 12 Pictorial Drawing WIRE OR HEAVY CORD. TYPICAL WING UPPER METHOD OF SUPPORTING ACTUATOR Figure 12-27 SURFACE WHEN CONNECTING OR DISCONNECTING LINKS A maintenance illustration. Notice that only the necessary detail is shown and IDLER LINK (M) that just enough shading is used to DRIVE LINK (J) emphasize and give form to the parts. IDLER LINK (H)

PIN (K)

ACTUATOR SUPPORT STRUCTURE

REMOVE PIN (K) TO DISCONNECT DRIVE LINK (J) FROM THE ACTUATOR. PIN (K) IS INSTALLED IN THE SAME MANNER TO CONNECT DRIVE LINK (J) TO THE ACTUATOR the center are made with thick lines to accent direction (Figure 12-28A), the top and front the shape. In Figure 12-26D, the edges meet- surfaces of a cube should be lighted. Therefore, ing at the center are made with thin lines. the right-hand surface should be shaded. In Thick lines are used on the other edges to bring Figure 12-28B, the front surface is unshaded out the shape. See Figure 12-27 for an exam- and the right surface is lightly shaded using ple of the use of a small amount of line shad- vertical lines. If the front surface has light shading. In this case, the shading is used to outline ing, then the right side should have heavier important parts of the drawing. shading (Figure 12-28C). Solid shading may sometimes be required to avoid confusion. If Surface Shading the front is shaded, then a darker shade may be Shading of the surface, or surface shading used on the right-hand side (Figure 12-28D). or rendering, can be done using board draft- Figure 12-28E was shaded in AutoCAD using ing techniques or computer software. In either the SHADE command. Notice that all three method, the theory of shading is the same. With visible sides are shaded differently to deﬁ ne the the light rays coming from the conventional 3D shape.

LIGHT SOURCE

FRONT

Figure 12-28 Some methods of rendering ABC the faces of a cube

Section 12.1 Types of Pictorial Drawing 421 Wash Rendering A wash rendering, or wash drawing, is a form of watercolor rendering that has tra- ditionally been done with watercolor and watercolor brushes. CAD drawings can be imported to an illustration program and “painted” to achieve the same effect. Wash rendering is commonly used to render architectural drawings and for advertising furniture and similar products in newspapers (see Figure 12-29). Wash rendering is highly specialized and is usually done by a commer- cial artist. However, some technical illustra- tors and drafters are occasionally required to do this type of illustrating. Figure 12-29 This illustration was done electronically. Notice Photo Retouching that the computer artist has achieved a Photo retouching is the process used to wash-rendered eﬀ ect. change details in a photograph. Retouch- ing can be done by hand or with computer software such as Adobe Photoshop®. Details photographs for use in publications. It can may be added, removed, or simply repaired. be used to change the appearance of speciﬁ c This process is often needed in preparing details or the entire photograph.

Section 12.1 Assessment Drafting Practice After You Read 5. In Figure 12-30 below, identify the following pictorial drawings as two-point perspective, one-point perspective, oblique Self-Check cabinet, isometric, or oblique cavalier. 1. Identify and describe the differernt types of pictorial drawing types. 2. Explain the differences in the three types of axonometric projection. 3. Explain how to make cavalier, normal, and cabinet oblique drawings. Academic Integration English Language Arts 4. The English language has many words whose meanings vary, depending on the use of the word in a particular context. Section 12.1 introduced the content vocabulary terms, cabi- Figure 12-30 net oblique and cavalier oblique, which have speciﬁ c drawing-related mean- Go to glencoe.com for this ings in mechanical drawing. How else book’s OLC for help with this can the words cabinet and cavalier be drafting practice. deﬁ ned?

422 Chapter 12 Pictorial Drawing 12.2 Creating Pictorial Drawings

Preview To develop a pictorial drawing, you must understanding the concepts involved and then apply them to a drawing using either board drafting or CAD techniques. What do you think are the diﬀ erences and similarities are of those techniques? Content Vocabulary • box method • isoplane Academic Vocabulary Learning these words while you read this section will also help you in your other subjects and tests. • principles • establish Graphic Organizer Use a table like the one below to organize notes about pictorial drawing techniques.

Drawing Techniques Go to glencoe.com for this Board Drafting CAD book’s OLC for a downloadable Isometric drawing version of this graphic organizer Oblique drawing Perspective drawing

Academic Standards

English Language Arts NCTE National Council of Teachers of English Developing Research Skills Use a variety of technological and information resources (e.g., NCTM National Council libraries, databases, computer networks, video, to gather and synthesize information and to create of Teachers of and communicate knowledge (NCTE) Mathematics

Mathematics

Numbers and Operations Compute ﬂ uently and make reasonable estimates (NCTM)

Section 12.2 Creating Pictorial Drawings 423 DIAMETER Isometric Drawing OF CIRCLE Techniques DRAW AN ISOMETRIC SQUARE How do you draw circles, nonisometric WITH THE SIDES EQUAL TO TO A lines, and reversed axes in isometric THE DIAMETER OF THE CIRCLE. construction?

Section 12.1 discussed the various types A of pictorial drawings and their applications. 4 1 This section describes how to apply the CD USE A 30–60 TRIANGLE TO principles of pictorial drawing using board LOCATE POINTS A, B, C, D, 32B AND 1, 2, 3, 4. drafting and CAD techniques. In isometric B drawing, order is important. For example, in board drafting, you must create the isomet- A ric lines—those that are parallel to the iso- 4 1 metric axes—before you can begin to draw CDR nonisometric lines. This section explains R WITH A AND B AS CENTERS AND C construction techniques and then takes you A RADIUS EQUAL TO A2, DRAW 32 ARCS AS SHOWN. step by step through practice exercises for B isometric drawing. A 1 Isometric Constructions 4 WITH C AND D AS CENTERS AND R CDR Before you attempt to create an isomet- A RADIUS EQUAL TO C4, DRAW D ric drawing using drafting instruments, you ARCS TO COMPLETE THE 32 ISOMETRIC CIRCLE (ELLIPSE). should understand the techniques used to cre- B ate various geometric shapes accurately. The Figure 12-31 following pages describe several procedures. Practice these techniques before you attempt Steps in drawing an isometric circle to create an isometric drawing.

Drawing Isometric Circles In isometric drawing, circles appear as ellipses. Because it takes a long time to plot a true ellipse, a four-centered approximation is generally drawn, especially for large isometric circles. Isometric circle templates may be used for small ellipses. Figure 12-31 describes how to create a four-centered approximation of an ellipse. Figure 12-32 shows isometric circles drawn on three surfaces of a cube. Figure 12-33 shows how to make an isometric drawing of the cylinder shown as a Figure 12-32 multiview drawing in Figure 12-33A. Follow these steps: Isometric circles on a cube 1. Draw an ellipse of the 3.00″ circle following the procedure shown in Figure 12-32. 2. Drop centers A, C, and D a distance equal 4. Complete the ellipses as in Figure 12-33C. to the height of the cylinder (in this case, Construct a line through C′D′ to locate the 4.00″) as in Figure 12-33B. points of tangency. Draw the arcs using the 3. Draw lines A′C′ and A′D′. same radii as in the ellipse at the top.

424 Chapter 12 Pictorial Drawing Figure 12-33 A A ABCR Steps in drawing an 2 R1 isometric cylinder CD C D

3.00 B B A1 A1

C1 D1 C1 D1 R 2 R1 4.00

Figure 12-34 R1 Drawing quarter R R rounds in isometric R drawings

R R

R R2 1

R R R1 2 = RIGHT ANGLE (90) R

5. Draw the vertical lines to complete the T 2 cylinder. Notice that the radii for the arcs TTR H 1 I at the bottom match those at the top. R T 2 1I R T To draw quarter rounds, use the method in T T Figure 12-34 or an ellipse template. In each H case, measure the radius along the tangent T lines from the corner. Then draw the actual perpendiculars to locate the centers for the T R isometric arcs. Observe that the method for 1 fi nding R and R is the same as that for fi nd- I 1 2 T T 1 R T T ing the radii of an isometric circle. When an T arc is more or less than a quarter circle, you R can sometimes plot it by drawing all or part of T T a complete isometric circle and using as much H 2 of the circle as needed. H I Figure 12-35 shows how to draw out- 2 side and inside corner arcs. Note the tangent points T and the centers 1, 11, 2, and 2. Figure 12-35 Constructing outside and inside arcs Drawing Irregular Curves Irregular curves in isometric drawings cannot be drawn using the four-center method. Using Isometric Templates To draw irregular curves, you must fi rst plot Isometric templates are made in a variety points and then connect them using a French of forms. They are convenient and can save curve. See Figure 12-36. time when you have to make many isometric

Section 12.2 Creating Pictorial Drawings 425 15 50 30 45 60

E A B C D E Figure 12-38 D Ellipse templates C B A drawings. Many of them have openings for Figure 12-36 drawing ellipses, as well as 60° and 90° guiding edges. Simple homemade guides like those in Constructing irregular curves Figure 12-37A are convenient for straight-line in isometric drawings work in isometric. These templates can be made to any convenient size. Figure 12-37B shows various ways to position the templates for making an isometric drawing. Ellipse templates such as those in Figure 12-38 are very convenient for drawing true ellipses. If you use these tem- 120 plates, your drawings will look better and you 30 30 will not have to spend time plotting approxi- 30 30 mate ellipses. See Chapters 3 and 4 for informa- 120 tion on templates and how to use them.

A DESIGN OF HOMEMADE ISOMETRIC TEMPLATES

Describe What is the drawing order in isometric drawing?

Isometric Drawing Creation Figure 12-39A shows a multiview drawing of a ﬁ ller block. To make an isometric drawing of the block, begin by drawing the isometric axes in the ﬁ rst position (Figure 12-39B). They represent three edges of the block. Draw them to form three equal angles. Draw axis line OA vertically. Then draw axes OB and OC using the 30°-60° triangle. The point at which the three lines meet represents the upper front corner O of the block (Figure 12-39C). Measure off the width W, the depth D, and the height H of the block on the three axes. Then draw lines parallel to the axes to make the isometric drawing of each block. To locate B VARIOUS POSITIONS OF TEMPLATES the rectangular hole in Figure 12-39D, lay off 1.00" along OC to c. Then from c, lay off 2.00" Figure 12-37 to c'. Through c and c', draw lines parallel to Simple isometric templates OB. In like manner, locate b and b' on axis OB and draw lines parallel to OC. Draw a vertical

426 Chapter 12 Pictorial Drawing 3.00 1.50 line from corner 3. Darken all necessary lines to complete the drawing as in Figure 12-39E. A Pictorial drawings, in general, are made to

2.00 4.00 show how something looks. Because hidden edges are not “part of the picture,” they are 1.00 normally left out. However, you might need

6.00 to include them in special cases, to show a certain feature. Figure 12-40 shows how to make an iso- 3.00 metric drawing of a guide. The guide is shown in a multiview drawing in Figure 12-40A. This drawing is more complex because it B C includes a circular hole and several rounded 120° surfaces. Study the size, shape, and relationship of the views in Figure 12-40 A before you B proceed. Then follow these steps: 120° 120° 1. Draw the axes AB, AC, and AD in the sec-

A ond position (see Figure 12-40B). 2. Lay off the length, width, and thickness measurements given in Figure 12-40A.

B That is, starting at point A, measure the length (3.00″) on AB; the width (2.00″) C on AC; and the thickness (.62″) on AD. O 3. Through the points found, draw isometric C H lines parallel to the axes. This “blocking in” produces an isometric view of the base. W 4. Block in the upright part in the same A D way, using the measurement given in the top view of Figure 12-40A. 5. Find the center of the hole and draw cen- 3 terlines as in Figure 12-40B. B 2 4 ″ b 1 C 6. Block in a .75 isometric square and draw

1 1 3 b C the hole as an approximate ellipse or use C an ellipse template. 1 1 O 2 D 2 1 7. To make the two quarter rounds, measure the .50″ radius along the tangent lines from both upper corners as in A Figure 12-40C. Draw real perpendiculars to ﬁ nd the centers of the quarter circles. Refer again to Figure 12-34 for information about drawing isometric quarter rounds. An ellipse circle template can also be used for this purpose. E 8. Darken all necessary lines. Erase all construction lines to complete the isometric drawing. See Figure 12-40D.

Nonisometric Lines Figure 12-39 To draw a nonisometric line, ﬁ rst locate Steps in making an isometric drawing its two ends, and then connect the points. Angles on isometric drawings do not show in

Section 12.2 Creating Pictorial Drawings 427 E J I F A 1.0 0 D G H C 1.25 2.00 • AJ,G I,H B .50

3.00 O.75 .75 R.50 A

2.00 D C 1.25 .62 B

2.00 B C 1.25 A

B .62 B .75 C D 30 E 30 H 3.00 1.0 0 D A .50 2.00 G C C A RADIUS • B RADIUS • I

E H C D J

G D C A

E D

D E

Figure 12-40 Figure 12-41 Creating an isometric drawing of a guide Drawing nonisometric lines

their true size. Therefore, you cannot measure ric lines are the slanted sides of the pack- them in degrees. ing block shown in the multiview drawing Figure 12-41 shows how to locate and in Figure 12-41A. To make an isomet- draw nonisometric lines in an isometric drawing of the block, use the following ric drawing using the box method. The procedure. box method involves the development of 1. Block in the overall sizes of the packing a framework, or box, that provides surfaces block to make the isometric box ﬁ gure as on which to locate points. The nonisomet- in Figure 12-41B.

428 Chapter 12 Pictorial Drawing 3. Connect points O and B to complete the B isometric angle.

A Follow the same steps to construct the B B angle on the top of the isometric cube. This method can be used to lay out any angle on 40 O A any isometric plane. A A O B Figure 12-43A is a multiview drawing of an object with four oblique surfaces. An isometric Figure 12-42 view of this object can be made using either the Constructing angles in isometric drawings box or the skeleton method. The box method involves the development of a framework, or box, that provides surfaces on which to locate 2. Use dividers or a scale to transfer distances points (see Figure 12-43B). The points are AG and HB from the multiview drawing then connected to develop the edges that form to the isometric ﬁ gure. Lay these distances the oblique surfaces. In the skeleton method off along line AB to locate points G and (see Figure 12-43C), points are located by tak- H. Then draw the lines connecting point ing measurements directly on the base triangle. D with point G and point C with point H. The points are then connected to develop the This is shown in Figure 12-41C. edges that form the oblique surfaces. 3. Complete the layout by drawing GJ and HI and by connecting points E and J to form a third isometric line, as in Figure 12-41D. 4. Erase the construction lines to complete Analyze Why is it not possible to measure the drawing (see Figure 12-41E). angles in degrees on isometric drawings?

Angles Reversed Axes To draw the 40° angle in Figure 12-42A, Sometimes you will need to draw an object use the following procedure. as if it were being viewed from below. To do 1. Make AO and AB any convenient length. so in isometric drawing, reverse the position Draw AB perpendicular to AO at any con- of the axes. Refer again to Figure 12-4. To venient place (see Figure 12-42A). draw an object using reversed axes, follow the 2. Transfer AO and AB to the isometric example in Figure 12-44. Consider how an cube in Figure 12-42B. Lay off AO object appears in a multiview drawing (see along the base of the cube. Draw AB par- Figure 12-44A). Then begin the isometric allel to the vertical axis. view by drawing the axes in reversed position

P P

BOX METHOD SKELETON METHOD ABC

Figure 12-43 Drawing oblique surfaces in isometric drawings

Section 12.2 Creating Pictorial Drawings 429 A B 2.00 .50 1.0 0 3.00 .25 2.00 .50 .50 .62SQ O.88 .50 3.00 A 2.25 1.50 .75 1.50 1.25SQ

1.75

.50 C

1.25

2.25 1.50 Figure 12-44 B Steps in making an isometric drawing with reversed axes

(see Figure 12-44B). Complete the view with dimensions taken from the multiview drawing (see Figure 12-44C). Darken the lines to .50 ﬁ nish the drawing. Long Axis Horizontal When long pieces are drawn in isometric, make the long axis horizontal as in Figure 12-45 or at 30°. For example, a long 1.75 3.75 object is shown in a multiview drawing in Figure 12-45A. See Figure 12-45B for the C beginning of an isometric drawing with the axes shown by thick black lines. In Figure 12-45C, the same object is drawn with the long axis at 30° to the horizontal. The overall size and shape of the object, along with the intended use of the object, determines which method should be used. Remember that in isometric drawing, Figure 12-45 you must draw circles ﬁ rst as isometric squares; Steps in making an isometric drawing then complete them by the four-center method with the long axis horizontal or by using an ellipse template. Dimensions of Isometric Drawings You can place dimensions on isometric drawing are read from the bottom of the sheet. ings in two general ways. The older method is However, because isometric drawings are to place them in the isometric planes and adjust not usually used as working drawings, the letters, numerals, and arrowheads to iso- they are seldom dimensioned at all. Refer metric shapes (see Figure 12-46A). The newer to Chapter 7 for more information about unidirectional system (see Figure 12-46B) is the aligned and unidirectional methods of simpler. In this system, numerals and letter- dimensioning.

430 Chapter 12 Pictorial Drawing .50 CUTTING PLANE O1.0 0

1.25 1.25

.50

1.OO 3.00 A 2.00

ALIGNED

AB .50

O1.0 0 Figure 12-48 1.25 An example of an isometric half section 1.25

.50 1.0 0 of three objects. Note the construction lines 3.00 B 2.00 showing the parts that have been cut away. Figure 12-48 is an illustration of an iso- UNIDIRECTIONAL metric half section. The construction lines in Figure 12-46 Figure 12-48A are for the complete outside view of the original object. Notice the outlines Two methods of dimensioning isometric views of the cut surfaces. Figure 12-48B shows how to create the section. Draw the complete outside view as well as the isometric cutting Isometric Sections plane. Then erase the part of the view that the Isometric drawings are generally “outside” cutting plane has cut away. views of an object. Sometimes, however, a sectional view is needed. To create a sectional view, take a section on an isometric plane—a plane that is parallel to one of the faces of the Explain Why do you not dimension isometric cube. See Figure 12-47 for isometric isometric drawings? full sections taken on a different plane for each

Figure 12-47 Examples of isometric full sections

Section 12.2 Creating Pictorial Drawings 431 Oblique Drawing Techniques How is perspective drawing more complex than isometric and oblique drawing?

In oblique drawing, the front of the object is easy to draw, because it is parallel to the picture plane. The rest of the drawing follows rules similar to those for isomet- Figure 12-50 ric drawings. Lines that are parallel to the Plotting oblique circles axes are drawn fi rst. This section explains construction techniques and then steps you through practice exercises for oblique pictorial drawing. factory for some purposes, but they will not Oblique Constructions be pleasing. Ellipse templates give much bet- As with isometric drawing, you should under- ter results. If you use a template, fi rst block stand how to draw the geometry in an oblique in the oblique circle as an oblique square. drawing before you begin a complete drawing. This shows where to place the ellipse. Block- The techniques used in oblique drawing are ing in the circle fi rst also helps you choose the described below. proper size and shape of the ellipse. If you do not have a template, plot the ellipse as shown Obliques in Figure 12-50. On the front face, circles and curves show in their true shape. On other faces, they show as ellipses. Draw the ellipses using the four- center method or an ellipse template. See Explain What is the four-center method? Figure 12-49A for a circle as it would be drawn on a front plane, a side plane, and a top plane. Figure 12-49B and C show an oblique drawing with arcs in a horizontal plane and in Oblique Drawing Creation a profi le plane, respectively. The procedure for making an oblique draw- When you draw oblique circles using the ing is much the same as that for creating an four-center method, the results will be satis- isometric drawing. Notice that the oblique

R R

A B C

Figure 12-49 Circles parallel to the picture plane are true circles. On other planes, they appear as ellipses.

432 Chapter 12 Pictorial Drawing 1.12 1.50

1.00 .38 1.62 O.38 .50 B 2.38 O1.25 O.62 A C D

2.12 B A R.56

.50

CD Figure 12-51 Steps in making an oblique drawing

drawing in Figure 12-51 can show every- C thing but the two small holes in true shape. B E Follow these steps: C B A

1. Draw or review the multiview drawing E A of the object to be drawn in oblique. See D F Figure 12-51A. B 2. Draw the axes AB, AC, and AD for the D F base in second position and lay off the A length, width, and thickness of the base C B E on the axes (see Figure 12-51B). E A B 3. Draw the base and block in the upright, D omitting the projecting boss (cylinder) F C F (see Figure 12-51B). D 4. Block in the boss and fi nd the centers of D A all circles and arcs. Draw the circles and arcs (see Figure 12-51C). C 5. Darken all necessary lines and erase construction lines to complete the drawing Figure 12-52 (see Figure 12-51D). Angles on oblique drawings Angles and Inclined Surfaces Angles that are parallel to the picture plane of the fi gure shows the plate in oblique draw- show in their true size. For all other angles, ings. In Figure 12-52B, the angles are paral- lay the angle off by locating both ends of the lel to the vertical plane. In Figure 12-52C, slanting line. they are parallel to the profi le plane, and in Figure 12-52A is a multiview drawing of a Figure 12-52D, they are parallel to the hori- plate with the corners cut off at angles. The rest zontal plane. In each case, the angle is laid off

Section 12.2 Creating Pictorial Drawings 433 Perspective Drawing Techniques What techniques for drawing inclined surfaces, circles, and arcs used?

Perspective drawing involves techniques FULL SECTION similar to those used for isometric and oblique drawings. However, perspective drawing is more complex, because you must consider line of sight, vanishing points, and other features. This section explains construction techniques and then takes you step by step through practice exercises for one- and two- HALF SECTION point perspective drawing.

Figure 12-53 Perspective Constructions Oblique full and half sections As with isometric and oblique drawing, you should understand how to draw the geometry in a perspective drawing before you begin to by measurements parallel to one of the axes. draw one. The techniques for inclined sur- These measurements are shown by the con- faces, circles, and arcs are described in the fol- struction lines. lowing paragraphs. Oblique Sections Like isometric drawings, oblique drawings Inclined Surfaces are generally “outside” views. Sometimes, how- Plot inclined surfaces in perspective by ever, you need to draw a sectional view. To do ﬁ nding the ends of inclined lines and con- so, take a section of a plane parallel to one of necting them. This drawing method is shown the faces of an oblique cube. See Figure 12-53 in Figure 12-54. for an oblique full section and an oblique half section. Note the construction lines indicating Circles and Arcs the parts that have been cut away. See Figure 12-55 for a two-point perspective of an object with a cylindrical surface. Points on the front and top views are located ﬁ rst and then are projected to the perspective Describe In what manner do angles that are view. A path is formed where the projection parallel to the picture plane appear? lines meet. The perspective arc is drawn along

Figure 12-54 Two-point perspective of an PP object with an inclined surface HL VPL VPR

434 Chapter 12 Pictorial Drawing TOP VIEW

FRONT VIEW SIDE VIEW PP

HL VPL VPR

Figure 12-55 Two-point perspective of an object with a cylindrical surface SP

ing sheet as in Figure 12-57A. A more

TOP VIEW interesting view is obtained if the top view is drawn slightly to the right or left of center. 2. Draw an edge (top) view of the picture ISOMETRIC plane (PP) through the front edge of the VIEW top view. 3. Draw the horizon line (HL). The loca- FRONT VIEW SIDE VIEW tion depends on whether you want the object to be viewed from above, at, or Figure 12-56 below eye level. Draw the ground line. Multiview and isometric drawings of an object to Its location in relation to the horizon be drawn in single-point perspective line determines how far above or below eye level the object will be viewed. See Figure 12-57A. the path using a French curve or an ellipse 4. To locate the station point (SP), draw template. a vertical line (line of sight) from the picture plane toward the bottom of the One-Point Perspective Creation sheet. Draw the line slightly to the right Refer to Figure 12-56, which shows an or left of the top view. Set your dividers object in multiview and isometric drawings. at a distance equal to the width of the Figure 12-57 shows how to draw the same top view. Begin at the center of vision of object in a one-point, bird’s-eye perspective the picture plan and step off 2 to 3 times view. Follow these steps: the width of the top view along the line 1. Decide on the scale to be used and draw of sight, to locate the station point. See the top view near the top of the draw- Figure 12-57B.

Section 12.2 Creating Pictorial Drawings 435 TOP VIEW

PP PICTURE-PLANE LINE (PP) HORIZON LINE (HL) GL

GROUND LINE (GL) HL VP SP A

W Figure 12-58 CENTER OF One-point (worm’s-eye) perspective VISION (CV)

W VANISHING POINT (VP) LINE OF SIGHT (LS) W PP FRONT STATION B VIEW POINT (SP)

VP HL GL

A PP SP VP HL

Figure 12-59 B GL One-point (normal) perspective

C SP

the station point. At point A on PP, drop PP a vertical line to the perspective view to VP HL establish the back edge. Draw a horizontal line through point B to establish the back top edge. GL 7. Proceed as in the previous step to lay out the slot detail (see Figure 12-57D). D SP 8. Darken all necessary lines and erase Figure 12-57 construction lines to complete the drawing. Procedure for making a one-point (bird’s-eye) perspective drawing In Figures 12-58 and 12-59, the object is drawn in one-point perspective in the other two positions. Notice that in all three cases, 5. Project downward from the top view to one face of the object is placed on the pic- establish the width of the front view ture plane (thus the name parallel perspec- on the ground line. Complete the front tive). Therefore, this face appears in true size view. and shape. True-scale measurements can be 6. The vanishing point is the intersection made on it. of the line of sight and the horizon line. Project lines from the points on the front view to the vanishing point (see Figure 12-57C). Establish depth dimen- Diﬀ erentiate How does the creation of sions in the following way: Project a line one-point and two-point perspective diﬀ er? from the back corner of the top view to

436 Chapter 12 Pictorial Drawing 6. Begin to block in the perspective view by projecting vertical dimensions from the front view to the line of sight (also called the measuring line) and then to the vanishing points. See Figure 12-61C. 7. Finish blocking in the view by projecting lines from points 1 and 2 on the top view to the station point. Where these lines cross the picture plane, drop vertical lines to the perspective view to establish the length and width dimensions. Project point 1' to VPL and point 2' to VPR. Figure 12-60 8. Add detail by following the proce- Multiview and isometric drawings of an object to dure described in steps 6 and 7. See be drawn in two-point perspective Figure 12-61D. 9. Darken all necessary lines and erase con- Two-Point Perspective Creation struction lines to ﬁ nish the drawing. Refer to Figure 12-60 for an object shown Figures 12-62 and 12-63 show the same in multiview and isometric drawings. See object drawn in the other positions. Notice Figure 12-61 for the method to draw this that none of the faces appear in true size and same object with a two-point bird’s-eye per- shape because none of them are on the pic- spective view. ture plane. 1. Draw an edge view of the picture plane (PP). See Figure 12-61A. Allow enough Perspective Grids space at the top of the sheet for the top Perspective drawing can take a lot of view. Draw the top view with one corner time. This is because so much layout work is touching the PP. In this case, the front needed before you can start the actual per- and side of the top view form angles of spective view. Also, a large drawing surface 30° and 60°, respectively. Other angles is often needed in order to locate distant may be used, but 30° and 60° seem to points. However, you can offset these disad- give the best appearance on the ﬁ nished vantages by using perspective grids. Exam- drawing. The side with the most detail ples are shown in Figure 12-64. There are is usually placed along the smaller angle many advantages in using grids. But there for a better view. is one major disadvantage: a grid cannot 2. Draw the horizon line (HL) and the show a variety of views. It is limited to one ground line (GL). type of view based on one set of points and 3. Draw a vertical line (line of sight) from one view location. However, for the work the center of vision (CV) toward the bot- done in some industrial drafting rooms, tom of the sheet to locate the station only one view may be needed. point. You can buy perspective grids, or you can 4. Draw line SP-B parallel to the end of the make your own. Creating your own grids is top view and line SP-C parallel to the front only practical, however, if you have a number of the top view (see Figure 12-61B). Use of perspective drawings to make in a special a 30°-60° triangle. style. 5. Drop vertical lines from the picture plane to the horizon line to locate vanishing point left (VPL) and vanishing point right (VPR). Draw the front or side Evaluate What are the advantages and view of the object on the ground line as disadvantages of perspective grids? shown in Figure 12-61B.

Section 12.2 Creating Pictorial Drawings 437 W

A 60 PICTURE-PLANE LINE (PP) 30

HORIZON LINE (HL) CENTER OF VISION W LINE OF SIGHT

GROUND LINE (GL) W

STATION POINT (SP)

C BPP CV VPL VPR HL

C 1 2 C BPP CV VPL VPR HL

2' 1'

D 1 2 C BPP CV VPL VPR HL

2' 1'

Figure 12-61 Procedure for making a two-point perspective drawing (bird’s-eye view)

438 Chapter 12 Pictorial Drawing Figure 12-62 Two-point (worm’s-eye) perspective PP

VPL VPR HL

Figure 12-63 Two-point (normal) PP perspective

VPL VPR HL GL

8 5 7

6 4

5 3 4 8 7 3 6 2 5 2 4 7 6 3 5 1 4 7 2 3 6 I 4 5 2 3 I 2 1 1 8 7 6 5 4 3 2 I 0 0 SINGLE-POINT PERSPECTIVE GRID TWO-POINT PERSPECTIVE GRID

Figure 12-64 Examples of perspective grids

CAD Techniques struct ellipses to represent circles or holes on Why would you choose to create a CAD isometric planes. AutoCAD creates “isocircles” drawing in 2D rather than in 3D? on all three planes. For rendering, however, the CAD work becomes somewhat more complex In many ways, making a 2D pictorial draw- because all rendering is done on 3D models. ing is a simpler process if you use a CAD The following sections discuss using AutoCAD system. For example, you do not have to con- to create various types of pictorial drawings.

Section 12.2 Creating Pictorial Drawings 439 LEFT TOP RIGHT .75 2.50 4.00 A Figure 12-66

ø.50 Positions of the isometric 1.50 crosshairs .75

three isometric plane orientations MIDPOINTS OF TOP AND BOTTOM LINES available for the cursor to choose in automatic drawing. By default, B the crosshairs are parallel to the left isometric plane, or isoplane. Figure 12-65 Development of a 2D You can change them to the top isometric drawing in and right planes using the ISO- AutoCAD PLANE command. However, it is faster and more convenient to use C one of the shortcut methods. You can toggle through the left, top, and right isoplanes by pressing CTRL+E or simply by pressing the F5 key. Both of these methods work while other 2D Isometric Drawing commands are active, which can simplify drawing tasks. Figure 12-66 shows the Techniques crosshairs in each isometric orientation. You can create isometric drawings in either 3. Change the crosshairs to the right two or three dimensions. If the drawing is to isoplane. be used as an isolated illustration or for a sin- 4. Draw the baseline of the block up and to gle purpose, a 2D isometric is often suffi cient. the right, as shown in Figure 12-65B. Drawings created in an engineering environ- Reenter the LINE command and use the ment are often created in three dimensions, Midpoint object snap to snap a second line because 3D models can be used for many dif- to the midpoint of the base. Extend the sec- ferent purposes. ond line vertically up from the midpoint of To create a 2D drawing of the block in the base, and make its length equal to the Figure 12-65A, begin by setting up the grid height of the block (1.50"). This temporary and snap spacing for an isometric drawing. vertical line will form the basis for the top The rest of the steps are then fairly easy. As in line and the isometric circle. board drafting, you should draw the isometric 5. At any location on the screen, draw a lines fi rst. Follow these steps: 2.50" line parallel to the isometric base- 1. Press the F7 key to turn on the grid, and line. This will become the top line of the enter ZOOM All. isometric block. After creating the line, 2. Enter the SNAP command at the key- move it into position by selecting the board. Notice the options that appear on midpoint of the 2.50" line as the base the Command line. Enter S (Style), and point for the move and snapping it to then enter I (Isometric). Enter a vertical the upper end of the temporary vertical spacing of .25 to fi nish setting the snap. line. Refer again to Figure 12-65B. Notice that the grid and crosshairs (cur- 6. Use the LINE command to connect the sor) change to an isometric orientation. ends of the top and bottom lines of the In Auto CAD, isoplane is one of the block.

440 Chapter 12 Pictorial Drawing 7. Switch the crosshairs to the left isoplane, tons is faster than using the View pull-down and draw the .50″ lines at the top and bot- menu. tom front corner and the top back corner 1. Use the PLINE command to create the to show the depth of the block. Then con- front view of the block just as you would ″ nect the .50 lines to complete the basic for a 2D orthographic drawing (see shape of the block (see Figure 12-65C). Figure 12-67A). 8. Isometric circles, or isocircles, are created 2. Enter the ISOLINES command and set a using the ELLIPSE command. When the new density of 10. This is not critical, but snap is set to Isometric mode, an additional it will show the isocircle in better detail option called Isocircle appears when you in the fi nished drawing. enter the ELLIPSE command. To create the 3. Enter the EXTRUDE command and select hole in the block, fi rst make sure the cross- the entire front view. Specify a height hairs are set to the right isoplane. Then equal to the thickness of the block (.50″). enter the ELLIPSE command and select the Press Enter to specify a taper angle of 0 Isocircle option. Use the Midpoint object (no taper). snap to snap the center of the isocircle to 4. Display the model from the SW Isomet- the midpoint of the temporary vertical line ric viewpoint to verify that the base is you created in step 4. The command acts now a 3D model. Then return to the pre- exactly like the CIRCLE command. Enter a vious view by picking the Undo button diameter of .50" to complete the isocircle. on the Standard or Standard Annotation Erase the temporary vertical line. The com- toolbar. Although this looks like a correct pleted block should look like the isometric isometric representation of the block, it drawing in Figure 12-65A. has one major fault as a solid model. The circle is not truly a hole. It is a solid cylinder in the middle of a solid block. You must subtract the extruded circle from the block to create a real hole. 5. Enter the SUBTRACT command, and pick anywhere on the outside of the base The Ortho Mode block as the solid from which to subtract. Like the snap and grid, the Ortho Press Enter and then select the cylinder mode is aff ected by the isometric to subtract. Remove hidden lines, and orientation. You can therefore use notice the difference in the model (see Ortho to keep lines aligned perfectly Figure 12-67B). The hole now passes all with the isometric axes. Use Ortho for the way through the block. Now you can all isometric lines. create the dowel that fi ts into the hole in the base. To create an exploded assembly, you must show the dowel above the base and in line with the hole. 3D Isometric Drawings 6. Enter the PLAN command and select the As you may recall from previous chapters, World option to return to the plan view AutoCAD provides standard, predefi ned iso- of the model. metric views for 3D objects and assemblies. 7. Enter the CIRCLE command. Use the Therefore, to create a 3D isometric, you sim- Center object snap to center the new ply build the objects in three dimensions, and circle on the hole in the base. Create the then change to an isometric view. The follow- circle with a diameter of .235. ing steps use the EXTRUDE command to cre- 8. Enter the EXTRUDE command, select ate a simple exploded assembly model of the the new circle, and extrude it to a base block from Figure 12-67 and the dowel height of 3.00 to create the dowel. The that fi ts into the hole. Note: Display the View dowel now exists and is in line with the toolbar to save time. Picking the view but- base block, but the base of the dowel is

Section 12.2 Creating Pictorial Drawings 441 12. Enter the LINE command and use the Center object snap to select the center of the top of the dowel as the starting point for the line. A 13. With Ortho still on, move the crosshairs straight down and select a point below the base block for the other endpoint of the line. The centerline should now run through the center of the dowel and D through the center of the hole in the base block. B 14. Pick the grip at the top of the centerline and move it up so that it extends beyond the top of the dowel. 15. Enter the HIDE command to see the exploded assembly. It should look similar to the one in Figure 12-67E.

Summarize How do you create a 3D C E isometric?

Figure 12-67 Steps to develop a 3D exploded assembly model in AutoCAD Oblique Drawing Techniques—CAD What is the advantage of using 3D Orbit in aligned with the top of the block (see creating oblique drawings? Figure 12-67C). To explode the assem- The procedures for creating an oblique bly, you must move the dowel up while drawing using a CAD system are much like keeping it in proper alignment. those for creating an isometric drawing. You 9. Switch back to the SW Isometric view- can create oblique drawings in either two or point to see the dowel and base block. three dimensions. Also, if Ortho mode is not on, turn it on now by pressing the F8 key. This will keep the dowel in proper alignment. 2D Oblique Drawings 10. Enter the MOVE command and select the Because the front view of an oblique draw- dowel. Move it straight up to clear the ing is at true size and shape, you can draw the base block, as shown in Figure 12-67D. front view as you normally would an ortho- 11. To complete the exploded assembly, graphic. Then you can change the snap to you need to create a trail to show how make the top and side views easier to create. the two parts ﬁ t together. In this case, Follow these steps: the trail will be a centerline that extends 1. Create the front view of the pole support through the center of the dowel and as in Figure 12-68A. the center of the hole in the base block. 2. Be sure the grid is on, and enter the Enter the LAYER command and cre- SNAP command at the keyboard. Enter R ate a new layer called Center. Specify (for Rotate) and pick the lower right cor- the Center linetype, and make this the ner of the front view as the base point. current layer. Enter a rotation angle of 30. The grid and

442 Chapter 12 Pictorial Drawing crosshairs rotate counterclockwise 30°. The procedure given here is for a cavalier Set the snap to .25. oblique drawn at 30°. The same procedure 3. Starting at the lower right corner of the can be used to create an oblique at any angle base, create the .75″ line that represents simply by changing the angle of the snap the depth of the pole support. Then rotation. To create a cabinet oblique, divide copy this line to the other key points as the depth dimensions by 2 before adding the in Figure 12-68B to deﬁ ne the depth. dimensions to the drawing. Use the Endpoint object snap to ensure accuracy. 3D Oblique Drawings 4. Copy the right upright, hole, and arched Like 3D isometric drawings, 3D oblique top of the front view to the back of the drawings are created as normal 3D models. object (see Figure 12-68C). The viewpoint is then changed to create the 5. Draw a line tangent to the front and back oblique. Follow these steps to create a model arcs to connect them, and add the lines of the pole support: to complete the right side of the object 1. Use the PLINE command to draw the (see Figure 12-68D). front view of the pole support shown in 6. To complete the oblique drawing, trim Figure 12-69A. away the unwanted lines from construc- 2. Set ISOLINES to 10. Then enter FACETRES tion, as shown in Figure 12-68E. and enter a new value of 1. FACETRES

.75

1.38 2.75

ø1.03 E A 1.75 .50

.50

Figure 12-68 Steps to develop a 2D oblique drawing in D AutoCAD

Section 12.2 Creating Pictorial Drawings 443 tage of using 3D Orbit is that you can actually see the object as you rotate the view. See Figure 12-70. Activate this feature using the 3DORBIT command. Move the viewpoint by dragging the mouse. Note: In some ver- A B sions of AutoCAD, the spherical orbit does not appear. The command works exactly the Figure 12-69 same in these versions, however. Steps to develop a 3D oblique drawing in AutoCAD

Recall What does extrude mean? is a command variable that controls the appearance of curved objects in 3D views. 3. Use the EXTRUDE command to extrude the object by the depth dimension, .75". Perspective Drawing 4. To create the hole, use the SUBTRACT command to subtract the hole from the Techniques—CAD pole support (if your version of AutoCAD How are the commands 3DORBIT, PLINE, supports this feature). and EXTRUDE used in perspective drawing? 5. For convenience, select the SW Isometric viewpoint from the View menu. As with Perspective drawing in AutoCAD is done the 3D isometric, the drawing is lying entirely in 3D. Therefore, the ﬁ rst step in on its side (see Figure 12-69A). Use the drawing any perspective view is to create a ROTATE3D command to rotate it into normal model of the object. Then you can position. Use the Xaxis option and select view the model either in parallel projection the lower front corner as the base point. (normal) or perspective views. The 3DORBIT Rotate it 90° to achieve the position in command provides an easy method of adding Figure 12-69B. perspective to a model. Follow these steps: 1. Create the box shown in Figure 12-71A AutoCAD includes a free-rotation feature using the PLINE and EXTRUDE com- known as 3D Orbit. This feature allows you mands. Extrude it to a height of .50 inch. to rotate a model in 3D space interactively 2. For convenience, switch to AutoCAD’s using a spherical orbit algorithm. The advan- preset SW Isometric view. 3. Enter the 3DORBIT command and right-click to present a shortcut menu. From this menu, pick Projec- tion and then Perspective. This places the model into the perspective mode. 4. Use the cursor to move the object in the perspective view. Create a view similar to the one in Figure 12-72. Press Enter to end the 3DORBIT command.

Figure 12-70 The 3D Orbit feature

444 Chapter 12 Pictorial Drawing 10.50 Figure 12-72 1.50 The 3DORBIT command oﬀ ers A better control for creating 3D perspective views.

5. Enter the HIDE command to remove BC hidden lines. As you can see, the object PARALLEL VIEW PERSPECTIVE VIEW retains the perspective view even after you end the 3DORBIT command. Figure 12-71 6. To remove the perspective view, reenter Use DVIEW to create a 3D perspective view. the 3DORBIT command, right-click, and choose Projection and Parallel.

Section 12.2 Assessment Drafting Practice After You Read 1. Make an isometric drawing of the bab- bitted stop shown in Figure 12-73. Start at the corner indicated by thick lines. Self-Check 1. Select and draw appropriate isometric sections. 2. Manipulate 3D models in AutoCAD to .70 achieve isometric, oblique, and perspective views.

Academic Integration .80 .80 Mathematics .50

3. Imagine you are applying for a loan to 6.00 start your freelance drafting business. The lender tells you that you will get a better rate if your debt payments-to-income 2.00 .50 ratio is low. Your debt payments would be

for any credit card balances or loans that .80 you are paying. If your monthly income is $1,200 and your monthly debt payments 3.25 1.50 total $180, what is your debt-payments- to-income ratio? Figure 12-73 Number and Operations To ﬁ gure out a ratio, you need to use a fraction. To calculate the DPR ratio, divide Go to glencoe.com for this the total debts by the total income. Con- book’s OLC for help with this vert the decimal outcome to a percent- drafting practice. age by moving the decimal point two places to the right and adding a percent sign (%).

Section 12.2 Creating Pictorial Drawings 445 12 Review and Assessment Chapter Summary Section 12.1 Section 12.2 • An isometric drawing is a drawing in which • Oblique drawings are classifi ed accord- the object is aligned with the three axes ing to the length of an object’s receding equally spaced at 120° angles. An oblique lines along the oblique axis: cavalier (full drawing is one in which two axes of the length), normal (three-fourths size), and object are parallel to the projection plane. A cabinet (one-half size). perspective drawing is a three-dimensional • One-point perspective is a view that has representation of an object as it appears to one vanishing point in comparison to a the eye from a particular point. two-point perspective that has two van- • Axonometric projection has three types: ishing points. diametric in which only two angles are • At times, it is necessary to show a sec- equal; trimetric in which all three angles tional (full or half) view of an isometric are different; and isometric in which the drawing. The process involves drawing axes form three equal angles of 120° on the object’s complete view and then eras- the plane of projection. ing the part that has been cut away. • AutoCAD provides predefi ned, standard views for 3D objects. The fi rst step is to build the object in three dimensions and then change to an isometric, oblique, or perspective view as your need dictates.

Review Content Vocabulary and Academic Vocabulary 1. Use each of these Content and Academic Vocabulary words in a sentence or drawing. Content Vocabulary • picture plane (p. 409) • box method (p. 426) • isometric drawing (p. 407) • cavalier oblique (p. 411) • isoplane (p. 438) • isometric axes (p. 407) • normal oblique (p. 411) Academic Vocabulary • axonometric projection • cabinet oblique (p. 411) • fundamental (p. 407) (p. 408) • perspective drawing (p. 411) • speciﬁ c (p. 407) • dimetric projection (p. 408) • vanishing point (p. 412) • principles (p. 422) • trimetric projection (p. 409) • technical illustration (p. 414) • establish (p. 434)

Review Key Concepts 2. Identify various pictorial drawing types. 3. Explain the differences between the three types of axonometric projection. 4. Make cavalier, normal, and cabinet oblique drawings. 5. Create one-point and two-point perspective drawings. 6. Select appropriate isometric sections. 7. Manipulate 3D models in AutoCAD to achieve isometric, oblique, and perspective views.

446 Chapter 12 Pictorial Drawing Technology Prep 8. The Information Age Multiple Choice Question Many historical eras have been given names For 11. You have a design prob- that in some way describe the particular gen- lem for which you need eration. Examples include the Age of Reason, a solution that is easy the Gilded Age, and the Age of Discovery. We to draw, can be drawn with- currently live in the Information Age. Why do out projecting from other views, and you think our era has been given this name? whose measurements can be made In a one-page paper, deﬁ ne the Information with a regular scale. Which of these Age and the emphasis it places on the process- drawings would meet your needs? ing and exchange of information. a. oblique c. 3D oblique b. axonometric d. isometric

9. Information Literacy TEST-TAKING TIP You hear the word economy at least daily. When you take a test, read the instructions How would you defi ne the word? Research before you begin. Failing to read directions the major economic systems used worldwide could cause you to completely misinterpret today. Go to libraries, databases, and computer what the test is asking you to do. networks to fi nd your sources. Be sure to keep bibliographical information on those sources. When you have enough information, write a fi ve-page paper explaining the two most commonly used economic systems. Be sure to use proper grammar, spelling, and organizational Win rules. Devote one page to critiquing the qual- Competitive ity of the individual sources you found. Events Mathematics 12. Architectural Drafting Organizations such as SkillsUSA offer a 10. Recording Finances variety of architectural, career, and draft- Ahra set up a spreadsheet for her company’s ing competitions. Completing activities fi nances. For each month, she has informa- such as the one below will help you pre- tion about earnings and expenditures. Create a pare for these events. monthly spreadsheet to display this data that Activity Work with a partner to brain- includes an equation for total cash fl ow. storm ways research and development Spreadsheets can be used as a tool to troubleshoot, or solve problems. For example, what kind Spreadsheets are basically tables, with rows of research might be needed to solve and columns, use to display information. technological problems? What is the dif- Computer spreadsheet programs can perform ference between technological and non- operations automatically when you input an technological problems? equation into the row or column in question. Step 1: Consider which data categories Go to glencoe.com for this book’s should go in the columns and rows. OLC for more information about Step 2: Create an equation for total cash competitive events. fl ow using earnings and expenditures. Create another line for this data as well.

Review and Assessment 447 12 Problems

Drafting Problems The drafting problems in this chapter are designed to be completed using board drafting techniques or CAD. For problems 1 through 15, determine an appropriate scale and create isometric drawings according to the instructions for each problem. Do not dimension.

1. Determine an appropriate scale, and create an isometric drawing of the object(s) assigned

from Figure 12-74. Note: These objects may also be used for oblique and perspective drawing practice.

2.50 2.50 24 50 13 76 27 6.00 5.50 130 2.50

1.20 1.20 30 .60

ABBRICK LAP JOINT CHOLLOW BLOCK METRIC

0'-10 2.30 1.30 2.25 .50 1'-4 1.0 0 6.00 5.30 4'-0 1'-8 3.30 2.00 0'-8 1.0 0 1.40 CONCRETE STEPS .70 DOOR STOP .25 DEBASE PAD F

30 .80 30 2.00 2.50 60 50 4.00 .30 .80 90 10 150 5.50 .30 2.00 24 70 1.80

30 16 2.00 V-BLOCK .80 TOY BOAT SAW BRACKET GHIMETRIC

Figure 12-74

448 Chapter 12 Pictorial Drawing 2. Make an isometric drawing of the stirrup 3. Make an isometric drawing of the brace

shown in Figure 12-75. Start the draw- shown in Figure 12-76. Start the drawing at the lower left. Note the thick starting at the lower right. Note the thick ing lines. starting lines.

.50

45 1.0 0 3.25 3.20 1.0 0 1.0 0

45 1.30

5.25 5.30 .50 .50 .50 .50

.50 .50

2.50 3.50 3.50 2.50

Figure 12-75 Figure 12-76

.80 30 .40 .80 4. Make an isometric drawing of the ratchet

.60 1.0 0 shown in Figure 12-77. 3.00 2.40

.80 .80

1.40

5.30 1.40 Figure 12-77 1.40 .80

Problems 449 12 Problems

5. Make an isometric drawing of the object(s) 6. Make an isometric full or half sec-

assigned from Figure 12-78. Note: These tion of the object(s) assigned from objects may also be used for oblique and Figure 12-78. perspective drawing practice.

METRIC Ø2.00 Ø2.00

3.00

3.00 1.50

1.50 3.00 6.00 3.00 2.00 6.00 Ø130 Ø110 6 1.0 0 1.50 .50 12

SPACER BASE SUPPORT AB CTRAY

R1.30 Ø1.75

2X R1.20

R1.80 2X R.80 3.50 4.30 Ø4.38 Ø3.00 .25 .90

1.50 1.0 0 LINK

.25 MAGNET DIDLER SPOOL E F

2X Ø.75

Ø12 1.50 3.00

1.50 5.50

METRIC .40 4.50 .75

6.00 .50 SQUARES R1.50 Ø64 Ø30 3.00 R1.20 .30 8 .40 3 GHICLAMP FLANGE CORNER BRACE

Figure 12-78

450 Chapter 12 Pictorial Drawing 7. Make an isometric drawing of the hung bearing shown in Figure 12-79. Most of the con-

struction is shown on the layout. Make the drawing as though all corners were square, and then construct the curves.

R.70 1.60 2X O .625

1.30 Figure 12-79 2.00

.62

1.50

5.50 Ø1.00 O 2.00

1.50 1.50 3.00 3.00 .60 1.30 TO BORDER

8. Make an isometric drawing of the bracket shown in Figure 12-80. Some of the construc-

tion is shown on the layout. Make the drawing as though all corners were square, and then construct the curves.

2.00 .60 1.60 .60 R.60 .80 1.00

.60

R.70 3.00 1.00 3.25

1.75 1.40 .60

Figure 12-80

R O.75 2 HOLES

Problems 451 12 Problems

9. Make an isometric drawing of the tablet shown in Figure 12-81. Use reversed axes. Refer to the

layout on the right.

84 64

12 12 24 12

60 6 146 50

10 20

METRIC

Figure 12-81

10. Make an oblique drawing of the angle

support shown in Figure 12-82.

38 26 20

150 R 12

20 120 50

90 88

Figure 12-82

452 Chapter 12 Pictorial Drawing 11. Make an oblique half or full section of the object(s) assigned from Figure 12-83. Note: These

objects may also be used for isometric and perspective drawing practice.

Ø1.30

Ø2.50 Ø2.50 Ø1.80 Ø1.80 Ø3.50 1.30 1.25 .60 .50 .50

ABDISK POST SUPPORT CFLANGE

Ø50 Ø2.00 Ø1.50 70 20

METRIC

Ø100 Ø4.10 Ø3.40 Ø4.00 Ø3.00 Ø2.70 .25

58 1.50 1.50 1.0 0 .50 .25 BUSHING STEP FLANGE SPOOL DE F

100

2.00 2.00

100 Ø4.00 METRIC 4.00 2.00 Ø50 .50 1.80 44 2.00 .80 20

SQUARE POST SUPPORT ROUND POST SUPPORT LUG GH I

Figure 12-83

Problems 453 12 Problems

12. Make a one-point perspective or two-point perspective drawing of each object assigned. Use any

suitable scale.

2.60 1.0 0 2.60 .80

.80 .90

4.00 .80 5.50 6.00 3.00

1.0 0 2.60 3.00

.80 .80

ABALIGNMENT BAR CORNER BRACE

3.50 2.00 .70 1.0 0 3.00 1.50 .50

1.0 0 1.50 .70 2.70 1.0 0 1.0 0 .50

6.00 2.00 .50 5.00 D TOOL SUPPORT

160 100 24 24 88 LETTER "N" 90° C 8 76

28 2X 20 R30 METRIC E V-BLOCK

4.50 8.00 100 METRIC 1.60

45° 1.0 0 Ø44 R40 3.50

45° 38 .90 12

FGBEARING DOVETAIL SLIDE

Figure 12-84

454 Chapter 12 Pictorial Drawing For problems 13 and 14, determine an appropriate scale and create a pictorial drawing

according to the instructions for each problem. Do not dimension unless instructed to do so.

13. To develop a good understanding of 14. Make instrument or CAD drawings of

the relationship of the various types the same tool support (Figure 12-84D) of pictorial drawings, make an isomet- in isometric, oblique cavalier, oblique ric, oblique cavalier, oblique cabinet, cabinet, one-point perspective, and two- one-point perspective, and two-point point perspective. Compare the sketches perspective sketch of the tool support you made in Problem 13 with the instru- shown in Figure 12-84D. ment or CAD drawings. Are they similar? Which type of pictorial drawing gives the most natural appearance?

Design Problems Design problems have been prepared to challenge individual students or teams of students. In these problems, you are to apply skills learned mainly in this chapter but also in other chapters throughout the text. They are designed to be completed using board drafting, CAD, or a combination of the two.

Challenge Your Creativity

1. Design an educational toy or game for chil- 4. Design a park bench to be made from at

dren ages three to ﬁ ve. Material optional. least two different materials. Develop Carefully consider safety issues. Include design sketches and pictorial drawings overall dimensions only. with dimensions. 2. Design a portable tool holder to accommo- 5. In this chapter, you used AutoCAD’s

date a cordless electric drill with accessories. SUBTRACT command to create a hole in The design should also incorporate a means a solid model. SUBTRACT is one of sev- for attaching the tool holder to a tool panel. eral commands that allow you to per- The accessories include at least a set of drill form Boolean operations (operations bits and screwdriver bits. Prepare a list of all based on Boolean mathematics) on 3D items before proceeding with the design. models. The other two common Boolean Material optional. Develop design sketches commands are UNION, which allows and pictorial drawings with dimensions. you to combine simpler models to create a single, more complex model, and Teamwork INTERSECTION, which creates a new 3. Design a device that can be used to convert model from the intersecting portion of

a portable electric router into a bench-type two existing models. Investigate these router. It can be designed as a fl oor model or commands and then use them to cre- a bench-top model. Make it easy and quick ate a solid model of the bracket shown Challenge to install and remove the router. Mate- in Figure 12-80. : It is possible rial optional. Each team member should to build this model using more than one develop design sketches of his or her design. construction method. Try at least two Select the best ideas from each to fi nalize different methods and determine which the team design. Prepare a fi nal set of picto- variation results in the smallest database rial drawings with dimensions. (fi le) size.

Problems 455