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TECHNICAL GRAPHICS COMMUNICATION PDF

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Technical graphics communication / Gary B. Bertoline. 1 Introduction to Graphics Communications, 5 PDF format for viewing and printing hard copies . unlikely user who is enthusiastic in name but complaining by post. 1 Only for. 3DS 4. Technical graphics communication bertoline 4th pdf. Technical graphics. TECHNICAL GRAPHICS COMMUNICATION FOURTH EDITION by Gary R. Bertoline. Postado por Green Mechanic. No comments: Post a Comment.


Technical Graphics Communication Pdf

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Technical Graphics Communication [Gary Robert Bertoline, Eric N Wiebe, Nathan W Hartman, William A Ross] on sppn.info *FREE* shipping on qualifying. Introduction to Graphics Communications for Engineers Fourth Edition Gary Thinking in the language of technical graphics, you will visualize. KWH. #PDF~ Technical Graphics Communication Free. Detail ○ ○ ○ ○ ○ ○. Author: William Ross Pages: pages Publisher.

They design products, systems, devices, and structures to improve our living conditions. Although problem solutions begin with thoughts or images in the mind of the designer, presentation devices and computer graphics hardware and software are powerful tools for communicating those images to others.

They can also aid the visualization process in the mind of the designer. As computer graphics have a greater impact in the field of engineering, engineers will need an ever-growing under-standing of and facility in graphics communications.

Each of the activities listed is so heavily slanted toward graphics communications that engineering is 92 percent graphically based. Courtesy of RealD Stereographics Figure 1.

Drawings are the road maps that show how to manufacture or build products and structures. Try to describe the part shown in Figure 1. The instructions must be of such detail that another person can make a sketch of the part. Now try verbally describing the part to another person. Have the person make a sketch from your instructions. These two examples will help you appreciate the difficulty in trying to use written or verbal means to describe even simple mechanical parts.

Refer to Figure 1. It is also important to note that air and water craft have thousands of parts. For example, the nuclear powered Sea Wolf class submarine has more than two million parts.

Try using verbal or written instructions to describe that! The 3-D model is used to design and visualize the hanger. The engineering drawings are used to communicate and document the design process. Tools are used to produce three basic types of drawings: CAD is computer soft-ware and related computer hardware that supplements or replaces traditional hand tools for creating models and tech-nical drawings Figure 1.

Since many industries have not fully integrated CAD into their design offices, it is necessary to learn both tradi-tional and computer design methods. Also, traditional tools are used for sketching, which is one of the most effective methods available to represent design ideas quickly. Design in Industry Going Virtual Virtual reality and simulation software tools hold the prom-ise of drastically slashing product development costs through the elimination of expensive physical prototypes.

With costs for the latest virtual reality VR tools and simula-tion systems coming down, automotive and aerospace manufacturers increasingly are seeking to deploy sophisti-cated, collaborative visualization systems throughout their product development planning organizations, as well as using virtual simulations for designing overall plant layouts and within manufacturing cells.

Although VR tools historically have been the domain of researchers, commercial applications in automotive, aero-space, and medical device manufacturing are becoming much more common.

Collaborative visualization may represent a new opportunity to manufacturers, particularly in the automo-tive industry where many major auto manufacturers are try-ing to persuade their top suppliers to adopt visualization technology.

Large-scale displays like the WorkWall enable manufacturing teams to collaborate in much the same way they used to work around drafting tables, but with realistic, full-scale 3-D models. Courtesy of Fakespace Systems Inc.

Copyright by Society of Manufacturing Engineers. All rights retained. This article may only be viewed or printed one 1 time for personal use. User may not save any text or graphical items to hard drives or duplicate this article in whole or in part in any medium. Courtesy of Fakespace Systems, Inc. A CAD system consists of hardware devices used in combination with specific software. There are many different hardware man-ufacturers and types of hardware devices, all of which are used to create, store, or output technical drawings and mod-els.

It is not uncommon in industry to have multiple input, storage, and output devices for a CAD system. Many tools were originally used in ancient Greece to study and develop geometry. Although computers may someday replace the need for some traditional tools, they are still useful today for draw-ing, and more importantly, for sketching. Traditional tools are devices used to assist the human hand in making technical drawings.

The assistance includes drawing lines straighter, making circles more circular, and increasing the speed with which drawings are made.

The tools typi-cally used to create mechanical drawings or sketches Figure 1. Wood and mechanical pencils 2. Instrument set, including compass and dividers 3. Descriptions of complex products or structures must be communicated with drawings. A designer uses a visual, nonverbal process.

A visual image is formed in the mind, reviewed, modified, and is ultimately communicated to someone else, all using visual and graphics processes. Courtesy of Staedtler, Inc. Table 1. ASME Y Two line weights are sufficient to follow the standards, a 0. These approximate widths are intended to differentiate between thin and thick lines and are not for control of acceptance or rejection of drawings. Thick lines are drawn using soft lead, such as F or HB.

Thin lines are drawn using a hard-er lead, such as H or 2H. Construction lines are very light and are drawn using 4H or 6H lead. Following are the standard linetypes and their applica-tions in technical drawings: Center lines are used to represent symmetry and paths of motion and to mark the centers of circles and the axes of symmetrical parts, such as cylinders and bolts. Break lines come in two forms: Break lines are used to show where an object is broken to save draw-ing space or reveal interior features.

Dimension and extension lines are used to indicate the sizes of features on a drawing. Section lines are used in section views to represent surfaces of an object cut by a cutting plane.

Cutting plane lines are used in section drawings to show the locations of cutting planes. Visible lines are used to represent features that can be seen in the current view.

Graphic communication

Hidden lines are used to represent features that cannot be seen in the current view. Scales 5. Irregular curves 6. Protractors 7. Erasers and erasing shields 8. Drawing paper 9. Circle templates Isometric templates 1. The media used for technical drawings are different types or grades of paper, such as tracing paper, vellum, and polyester film. Tracing paper is a thin, translucent paper used for detail drawings. Vellum is a tracing paper chemically treated to improve translucency.

Polyester film, or its trade name Mylar, is transparent, waterproof, and difficult to tear. Mylar can be used for lead pencil, plastic-lead pencil, or ink drawings. Mylar is an excellent drawing surface that leaves no trace of erasure.

Special papers have also been developed for CAD plotters. For example, plotter paper used for fiber-tipped pens has a smooth or glossy surface to enhance line def-inition and minimize skipping. Often, the paper comes with a preprinted border, title block, and parts list Figure 1.

Each paper size is designated by a letter, as shown in Table 1. The approximate dimensions shown on some linetypes are used as guides for drawing them with traditional tools.

The technical drawing at the top shows how different linetypes are used in a drawing. Stitch lines are used to indicate a sewing or stitching process. Chain lines are used to indicate that a surface is to receive additional treatment. Symmetry lines are used as an axis of symmetry for a particular view.

It is important that you understand and remember these dif-ferent linetypes and their definitions and uses, because they are referred to routinely throughout the rest of this book.

CAD software provides different linestyles for creating standard technical drawings. The thicknesses of lines on a CAD drawing are controlled by two different means: Visualization—the ability to mentally control visual information.

Graphics theory—geometry and projection techniques. Standards—sets of rules that govern how parts are made and technical drawings are represented. Conventions—commonly accepted practices and methods used for technical drawings.

CGT Technical Graphics Communications

Tools—devices used to create engineering drawings and models, including both handheld and computer tools. Applications—the various uses for technical graphics in engineering design, such as mechanical, electrical, and architectural.

Each chapter in the text will explain the graphics theory important for a topic, integrate the visualization practices, explain the relevant standards and conventions, demon-strate the tools used to create drawings, and apply the topic to engineering design. Learning to communicate with drawings is very similar to learning to write or speak in a language. For someone inexperienced in technical drawing, the learning process is very similar to learning a new language.

There is a set of rules that must be learned in order to communicate graphically or when learning a new language. You will soon find out that graphics is a very effective method of supporting the design process.

These new processes and technolo-gies can extend the circle of people in an organization who are involved in design. Many of these future trends are beginning to combine the design and manufacturing processes into a whole. A few trends even take a more global approach of attempting to control the entire enterprise. Today, however, the importance of sharing design ideas with others is even more important. One technique that is becoming popular is the sharing of design ideas through various computer graphics tech-niques.

The following is a list in order of realism and interactivity that can be produced with computer graphics tools. Test your written description by having someone attempt to make a sketch from your description.

Title Block for D and E. Is this mental image 2-D or 3-D? Try to put words to each feature of the TV you are drawing. In this problem you will experience the difficulty in trying to verbally describe an object with enough detail for it to be manufactured. Bezier, or George Lucas. The rise R is one-fourth the span of the truss. Construct the irregular polygon shown in the figure, using the given dimensions, on an A- or A4-size sheet. Do not dimension. Construct the centering plate, using the given dimensions.

All of the angles are proportional to angle A. Place the drawing on an A-or A4-size sheet. Construct the retaining ring shown in the figure.

Use an A-size sheet and triple the size of all radii. A laser beam directed from source Ais reflected at a degree angle from mirror B to mirror C, then onto the horizontal machine surface. Draw the mirrors, machine surface, and light path. Determine angle X for mirror C. Angle Y must equal angle Z angle of incidence equals angle of reflection. Construct the pump gasket shown in the figure, using a B-size sheet.

Construct the chamber clip shown in the figure, using a B-size sheet. Sketch Number: Problem Worksheet Sketch Number: Define technical sketching. Understand how sketching integrates into the design process. Identify and define two types of sketches. Create a design sketch using pencil or computer.

Identify and use sketching tools. Use grid paper to create sketches. Lay out a sketch using proportions. Understand the difference between pictorial and multiview projection. Create a perspective sketch. Create an isometric sketch. Create an oblique sketch. Create a multiview sketch.

Identify the types and precedence of lines. Follow good hand-lettering practice. Identify important practices when using CAD for lettering. Such sketches have traditionally been done freehand; today, CAD systems can also be used. A technical sketch is generally less finished, less structured or restricted, and it takes less time than other types of freehand illustrations.

Also, a technical sketch may communicate only selected details of an object, using lines; whole parts of an object may be ignored, or shown with less emphasis, while other features may be shown in great detail.

Technical sketches can take many different forms, depending on the clarity needed and the purpose of the sketch, both of which depend on the audience for which the All rights reserved. Figure 2. For example, a sketch made quickly to record a fleeting design idea may be very rough Figure 2. This type of sketch is for personal use and is not meant to be understood by anyone but the individual who produced it. A sketch may also use the format of a more formal, multiview drawing intended to be used by someone who understands technical drawings Figure 2.

However, this type of sketch would not be appropriate for a nontechnical person. Pictorial sketches would be used to further clarify the design idea and to communicate that idea to nontechnical individu-als Figure 2.

Shading can be used to further enhance and clarify a technical sketch Figure 2. Technical sketches are used extensively in the first ideation stage of the design process and are an infor-mal tool used by everyone involved in the design and For example, an industrial engineer might make several sketches of a layout for a factory floor.

Many designers find that sketching becomes part of their creative thinking process. Each sketch is used as a stepping stone to the next sketch or drawing, where ideas are refined, detail is added, and new ideas are formed.

On a large project, hundreds of sketches are created, detailing both the successful and the unsuccessful approaches considered for solving the design problem. Since all but the smallest of design projects are collabora-tive efforts, sketches become important tools for commu-nicating with other members of the design team.

At the early stages of the design process, highly refined, detailed drawings can actually impede the exploration of alternative ideas. What is needed are informal, nonrestric-tive sketches that can communicate both geometric and nongeometric information and can be produced quickly and changed easily. Technical sketching, being fast and less restrictive, can convey ideas at a level of detail that communicates the design intent and, at the same time, can allow the viewers to imagine for themselves how different solutions might further the design.

Sketches as communi-cations tools encourage collaborative contributions from other members of the design team. Although variations on these tools are numerous and sophisticated, the goal of technical sketching is simplifica-tion. Just a couple of pencils, an eraser, and a few sheets of paper should be all that is needed. Many a great design idea was born on the back of a napkin with a No.

This type of sketch is more appropriate for technical illustrations than for design communications. Irwin drawing contest winner Tim Brummett, Purdue University.

Although there may be a temptation to use straight-edges, such as T-squares and triangles, a minimum amount of practice should allow you to draw lines good enough for sketches without these aids.

Mechanically drawn lines can slow you down, add a level of accuracy not needed in the early stages of a design, and restrict the types of forms explored. Pencils The lead used in pencils comes in many different hardnesses; the harder the lead, the lighter and crisper the line. For general-purpose sketching, leads in the H and HB range will give you acceptable lines. If the lead is much harder, the lines will be too light and hard to see.

In addi-tion, hard lead has a tendency to puncture and tear some of the lighter-weight papers used in sketching. On the other hand, if the lead is too soft, too much graphite is deposited on the paper and can be smudged easily. Leads in the mid-dle range allow for a dark, relatively crisp line. Eraser Erasing should only be used to correct mistakes in a line, not to make changes in a design. Such changes should be recorded on a separate sketch, and the original C Figure 2.

Still, most people find that a small amount of erasing is helpful. Usually, the eraser on the end of the pencil is sufficient. However, if you are going to do a lot of sketching, you may need a separate eraser, and one of any size or shape will do. You might consider a gum eraser, since they leave less residue when used. Paper There is a wide range of paper choices for sketch-ing including a napkin you could draw on during lunch.

Because of the difficulty of drawing long lines freehand, paper much larger than that is normally not useful for a single sketch. On the other hand, larger paper is useful for drawing multiple sketches that should be visually grouped together. Plain bond paper with no lines offers the highest degree of flexibility; lined paper tends to lock you in visually to drawing along the lines. However, when you want the guidance of existing lines on the paper, it is most useful to have the lines running along both dimensions, forming a grid.

Two of the most common grid papers used in sketching are square grid Figure 2. Common grid densities run from 4 to 10 lines per inch. A less common type of grid paper is perspective, which is used to create another type of pictorial sketch Figure 2.

Often, it would be useful to have grid lines for the sketch, but not for the final drawing. One way this can be achieved is to sketch on thin, plain, semitransparent trac-ing paper laid over the grid paper and taped down so that the grid lines show through. When the sketch is done, it is untaped from the grid paper and viewed without the grid lines behind it. This technique is also a money saver because grid paper is more expensive than tracing paper often called trash paper , which can be bought in bulk on rolls.

The other advantage to tracing paper is that it can be laid over other sketches, photos, or finished technical drawings. A light table can be used to improve the tracing process. Tracing is a fast, accurate method for refining a design idea in progress or for using an existing design as the starting point for a new one. The following sections describe common techniques used to produce good sketches quickly.

The discussions cover the tools and the techniques for creating straight lines, curves such as cir-cles and arcs , and proportioned views. With patience and practice, it is possible for you to become good at making quick, clear sketches, regardless of your experience and natural drawing ability. Over a period of time and with practice you will be able to acquire the skills and knowledge necessary to create design sketches.

Sketching is based on seeing perception and visual thinking through a process of seeing, imaging, and representing Figure 2. Seeing is our primary sensory channel because so much infor-mation can be gathered through our eyes. It is our best-developed sense and one we take for granted every day as we easily move through our environment. Seeing empowers us to sketch. Imaging is the process that our minds use to take the visual data received by our eyes to form some structure and meaning. Representing is the process of creat-ing sketches of what our minds see.

Boring in , you can see either the head of an older woman or the profile of a younger woman. The illustration on the right can be viewed as either a vase or two profiles of the same person looking at each other. Figures 2. It is also possible to make sketch-es of objects that cannot exist in the real world. Escher was a genius at creating sketches and drawings of objects or environments that could not exist in reali-ty Figure 2.

Practice Exercise 2. Images often appear spontaneously in response to a memory recall. Your bedroom where you grew up as a child, or the street you lived on. A close relative, a famous actor, or a close friend from high school. A basketball sitting at center court on your high school gym floor. Try sketching the basketball on the floor. Your response to these written prompts is an example of your visual memory.

You are thinking visually, which is a very powerful way of thinking when designing. Escher Company-Holland. The lines or outlines of an object are used to represent the edges and contours of objects we see in the world. If we sketch the boundaries, an object slowly takes shape and we begin to recognize it as a familiar object. This technique of sketching the out-line of an object is called contour sketching and is an important technique used by novice sketchers to gain con-fidence in their sketching ability.

Contours on objects can take the form of edges of an object, lines that separate contrasting light or color, changes in the surface of an object, and overlapping parts. The primary reason for con-tour sketching is to develop your visual acuity and sensi-tivity to important object features, which are needed to create accurate sketched representations. When you first learn how to use contour sketching, begin by slowly tracing the outline of an object with your eyes while slowly sketching what you see.

At first the sketch may seem crude and out of proportion, but with practice your sketches will be quite good. Both tech-niques are useful when learning how to observe and cre-ate sketches of what you see. Making a Contour Sketch In this exercise, you are to create a sketch of the stapler shown in Figure 2. Step 1. Using a plain piece of white paper and a soft lead pencil, place your drawing hand with the pencil near the center of the paper.

Step 2. Orient the paper in a comfortable position for sketching. Step 3. Comfortably and in a relaxed manner, very slowly begin to trace the outline of the object with your eyes. Step 4. Slowly move your pencil across the paper as your eyes scan the outline of the object.

Do not erase or sketch over lines and do not look at your sketch. Sketch very slowly and deliberately. Step 5. Continue to draw each edge as you view it at a slow and deliberate pace. Step 6. Look at your sketch after you have finished viewing the contours of the object.

This technique is used to improve your sketching ability. In this example, the contour sketch was created without looking at the paper. Making a Modified Contour Sketch In this exercise, you are to create a contour sketch, but you will be able to look at your sketch as you are working Figure 2.

Do not erase or sketch over lines. Occasionally look at your sketch to match it with the object being drawn. Continue to draw each edge and interior edges at a slow and deliberate pace as you view the object.

In this technique you concentrate on the spaces In other words, you concentrate on the geometry of the objects, such as lines, curves, angles, and tangencies, and not on the names of the objects, such as handle, hole, base, cube.

An example of a negative space sketch is shown in Figure 2. Notice that the object itself is not shaded and lacks details, but the space surrounding the object is shaded. In this technique you take a photograph of a recognizable object, such as a chair, and turn it upside-down before sketching it. By turning it upside-down you can concentrate on the shape and form of the object, allowing you to create a better sketch.

Making a Negative Space Sketch For this exercise, you are to create a negative space sketch of the object shown in Figure 2. Use a plain sheet of white paper and begin by sketching the box surrounding the object. Sketch over the top of the negative spaces in the figure to reinforce that you are going to be sketching the negative spaces and not the object itself.

Focus on one of the outlined negative spaces just created in step 2 until you can visualize the negative space. Now begin sketching the negative space form on your sheet of paper. Concentrate on drawing lines and curves by determining the angles, lengths, tangencies, and other geometric characteristics. Repeat steps 3 and 4 until all the negative space has been created. Courtesy of Lunar Design Incorporated. Carefully sketch the outline of the object by concentrating on the geometry or form and not the names of the part, such as legs or feet.

By doing so you will be able to create a more accurate sketch of the object. Lines created for sketches differ from mechanically produced lines in that they are not constrained or guided by instruments, such as a T-square, template, or compass. Instead, the lines are guided strictly by the eye and hand.

Such lines have a different aesthetic quality than mechanical lines Figure 2. At a micro level, sketched straight lines are uneven; at a macro level, they should appear to follow a straight path without any interruptions Figure 2. One of the easiest guides to use for sketched lines is grid paper.

Lines drawn right on the grid are the easiest to produce, and even those lines that are offset but parallel to a grid line are fairly easy to produce. The idea is to keep your sketched line a uniform but not necessarily equal distance between two existing grid lines. Curved lines, straight lines not parallel to a grid line, and lines drawn without the aid of a grid are more diffi-cult. In all of these cases, the lines are drawn as interpola-tions between two or more points.

Quite often, the sketched line is built up from a sequence of two or three passes with the pencil Figure 2. The first pass is drawn light, using a hard lead, such as a 4H, sharpened to a point, and may not be as straight as your final line will be; however, it should provide a path on top of which the final, even, darker line is drawn.

For particu-larly long lines, the initial line may be drawn in segments, coming from the two endpoints and meeting in the middle; however, the final line should be drawn in one single pass to avoid choppiness. If necessary, another pass can be used to darken or thicken the line. Long lines are difficult to control, even for someone with a lot of experience. If you cannot choose a drawing scale that reduces the size of the sketch, use grid paper as a guide, drawing either directly on the grid paper or on tracing paper placed on top of the grid paper.

If the line is parallel and rel-atively close to the edge of the paper, you can rest a finger or a portion of your palm along the edge of the paper to sta-bilize your drawing hand Figure 2. If necessary, you can use a ruler or a scrap of paper to mark a series of points on the sketch, but this will slow you down a bit. Another technique that helps when drawing lines of any length is changing the orientation of the paper. Sketching paper should not be fixed to your drawing sur-face.

Instead, you should be able to rotate the paper freely, orienting it in the direction that is most comfortable. Practice will determine which orientation is best for you.

Many people find that drawing the lines by moving away from or toward the body, rather than from left to right, produces the quickest, straightest lines; others find it most comfort-able if the paper is angled slightly away from the body. Mechanical Sketched Figure 2. The light line is then drawn over and darkened. The following summarizes the techniques used to sketch straight lines: Do not fix the paper to the surface. One technique is to use the edge of the paper as a guide for your hand A.

Another technique is to mark equal distances from the edge of the paper using a marked scrap of paper as a guide B. The marks are then used as a guide to produce the line. Refer to Figures 2. Comfortably and in a relaxed manner, position your hand so that the pencil is close to one of the marked end-points of the first line to be sketched. Sketch the top line first, to avoid smearing newly sketched lines with your hand.

Quickly scan the two endpoints of the first line to determine the general direction in which you will be sketching. Repeat steps 4 and 5 until the other end of the line is reached. Step 7. Return to the starting point of the line and overdraw the line segments with a slightly longer, heavier stroke, to produce a thick, dark, more continuous straight line.

Step 8. Repeat steps 3 through 7 to sketch the remaining straight lines. The most common curve is a circle or circular arc. Although very small circles and arcs can be drawn in one or two strokes and with no guide points, larger circles need some preliminary points.

The minimum number of points for a circle is four, marked on the perimeter at equal degree intervals. For an arc, use at least one guide point for every 90 degrees and one at each end. One way is to draw a square box whose sides are equal to the diameter of the circle Figure 2. The midpoints on each side of the square mark the points where the circle will touch the square. These points are called points of tangency.

More guide points can be added by drawing the two diagonals across the square. The center of the circle being sketched is the point where the diagonals cross Figure 2. Mark the guide points on each diagonal approximately two-thirds the distance from the center of the circle to the corner of the square. This distance is the approximate radius of the circle Figure 2.

As with longer straight lines, large arcs and circles are harder to draw and may need guide points marked at more frequent intervals. To do this, it is handy to use a scrap of paper with the radius marked on it Figure 2. Circular arcs are drawn the same way as circles, adjust-ing the number of points to suit the degree of curvature i. Noncircular arcs, however, can be more difficult. Since these lines are only to be sketched, cal-culating the points that the curve should pass through is too involved and is not recommended.

Simply use the eye to estimate guide points and then gradually draw a curve to pass through those points. Ellipses and curves in multiview drawings are two special cases treated later in this chapter. As with straight lines, positioning the paper and using a relaxed grip are important for helping you create good curves.

Unlike straight lines, curves are usually best drawn in a series of arcs of not more than 90 degrees. After each arc is drawn, rotate the paper for the next seg-ment of arc.

With practice you may be able to eliminate rotating the paper for smaller arcs, but you will probably still have to do so for larger ones. Refer to Figure 2. Orient the paper in a comfortable position and relax your grip on the pencil. Center lines are used to represent symmetry and paths of motion and to mark the centers of circles and the axes of symmetrical parts, such as cylinders and bolts.

Break lines come in two forms: Break lines are used to show where an object is broken to save draw-ing space or reveal interior features.

Dimension and extension lines are used to indicate the sizes of features on a drawing. Section lines are used in section views to represent surfaces of an object cut by a cutting plane. Cutting plane lines are used in section drawings to show the locations of cutting planes.

Visible lines are used to represent features that can be seen in the current view. Hidden lines are used to represent features that cannot be seen in the current view. Scales 5. Irregular curves 6. Protractors 7. Erasers and erasing shields 8. Drawing paper 9. Circle templates Isometric templates 1. The media used for technical drawings are different types or grades of paper, such as tracing paper, vellum, and polyester film. Tracing paper is a thin, translucent paper used for detail drawings.

Vellum is a tracing paper chemically treated to improve translucency. Polyester film, or its trade name Mylar, is transparent, waterproof, and difficult to tear. Mylar can be used for lead pencil, plastic-lead pencil, or ink drawings. Mylar is an excellent drawing surface that leaves no trace of erasure.

Special papers have also been developed for CAD plotters. For example, plotter paper used for fiber-tipped pens has a smooth or glossy surface to enhance line def-inition and minimize skipping. Often, the paper comes with a preprinted border, title block, and parts list Figure 1. Each paper size is designated by a letter, as shown in Table 1. The approximate dimensions shown on some linetypes are used as guides for drawing them with traditional tools.

The technical drawing at the top shows how different linetypes are used in a drawing. Stitch lines are used to indicate a sewing or stitching process. Chain lines are used to indicate that a surface is to receive additional treatment. Symmetry lines are used as an axis of symmetry for a particular view. It is important that you understand and remember these dif-ferent linetypes and their definitions and uses, because they are referred to routinely throughout the rest of this book.

CAD software provides different linestyles for creating standard technical drawings. The thicknesses of lines on a CAD drawing are controlled by two different means: Visualization—the ability to mentally control visual information.

Graphics theory—geometry and projection techniques. Standards—sets of rules that govern how parts are made and technical drawings are represented. Conventions—commonly accepted practices and methods used for technical drawings.

Tools—devices used to create engineering drawings and models, including both handheld and computer tools. Applications—the various uses for technical graphics in engineering design, such as mechanical, electrical, and architectural. Each chapter in the text will explain the graphics theory important for a topic, integrate the visualization practices, explain the relevant standards and conventions, demon-strate the tools used to create drawings, and apply the topic to engineering design.

Learning to communicate with drawings is very similar to learning to write or speak in a language. For someone inexperienced in technical drawing, the learning process is very similar to learning a new language.

There is a set of rules that must be learned in order to communicate graphically or when learning a new language. You will soon find out that graphics is a very effective method of supporting the design process. These new processes and technolo-gies can extend the circle of people in an organization who are involved in design. Many of these future trends are beginning to combine the design and manufacturing processes into a whole.

A few trends even take a more global approach of attempting to control the entire enterprise. Today, however, the importance of sharing design ideas with others is even more important.

One technique that is becoming popular is the sharing of design ideas through various computer graphics tech-niques. The following is a list in order of realism and interactivity that can be produced with computer graphics tools. Test your written description by having someone attempt to make a sketch from your description.

Title Block for D and E. Is this mental image 2-D or 3-D? Try to put words to each feature of the TV you are drawing. In this problem you will experience the difficulty in trying to verbally describe an object with enough detail for it to be manufactured. Bezier, or George Lucas. The rise R is one-fourth the span of the truss. Construct the irregular polygon shown in the figure, using the given dimensions, on an A- or A4-size sheet.

Do not dimension. Construct the centering plate, using the given dimensions. All of the angles are proportional to angle A. Place the drawing on an A-or A4-size sheet. Construct the retaining ring shown in the figure. Use an A-size sheet and triple the size of all radii.

A laser beam directed from source Ais reflected at a degree angle from mirror B to mirror C, then onto the horizontal machine surface. Draw the mirrors, machine surface, and light path. Determine angle X for mirror C. Angle Y must equal angle Z angle of incidence equals angle of reflection. Construct the pump gasket shown in the figure, using a B-size sheet. Construct the chamber clip shown in the figure, using a B-size sheet.

Sketch Number: Problem Worksheet Sketch Number: Define technical sketching. Understand how sketching integrates into the design process. Identify and define two types of sketches. Create a design sketch using pencil or computer. Identify and use sketching tools. Use grid paper to create sketches. Lay out a sketch using proportions. Understand the difference between pictorial and multiview projection.

Create a perspective sketch. Create an isometric sketch.

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Create an oblique sketch. Create a multiview sketch. Identify the types and precedence of lines. Follow good hand-lettering practice. Identify important practices when using CAD for lettering. Such sketches have traditionally been done freehand; today, CAD systems can also be used.

A technical sketch is generally less finished, less structured or restricted, and it takes less time than other types of freehand illustrations.

Also, a technical sketch may communicate only selected details of an object, using lines; whole parts of an object may be ignored, or shown with less emphasis, while other features may be shown in great detail.

Technical sketches can take many different forms, depending on the clarity needed and the purpose of the sketch, both of which depend on the audience for which the All rights reserved. Figure 2.

For example, a sketch made quickly to record a fleeting design idea may be very rough Figure 2. This type of sketch is for personal use and is not meant to be understood by anyone but the individual who produced it. A sketch may also use the format of a more formal, multiview drawing intended to be used by someone who understands technical drawings Figure 2. However, this type of sketch would not be appropriate for a nontechnical person.

Pictorial sketches would be used to further clarify the design idea and to communicate that idea to nontechnical individu-als Figure 2. Shading can be used to further enhance and clarify a technical sketch Figure 2. Technical sketches are used extensively in the first ideation stage of the design process and are an infor-mal tool used by everyone involved in the design and For example, an industrial engineer might make several sketches of a layout for a factory floor.

Many designers find that sketching becomes part of their creative thinking process. Each sketch is used as a stepping stone to the next sketch or drawing, where ideas are refined, detail is added, and new ideas are formed.

On a large project, hundreds of sketches are created, detailing both the successful and the unsuccessful approaches considered for solving the design problem. Since all but the smallest of design projects are collabora-tive efforts, sketches become important tools for commu-nicating with other members of the design team. At the early stages of the design process, highly refined, detailed drawings can actually impede the exploration of alternative ideas. What is needed are informal, nonrestric-tive sketches that can communicate both geometric and nongeometric information and can be produced quickly and changed easily.

Technical sketching, being fast and less restrictive, can convey ideas at a level of detail that communicates the design intent and, at the same time, can allow the viewers to imagine for themselves how different solutions might further the design.

Sketches as communi-cations tools encourage collaborative contributions from other members of the design team. Although variations on these tools are numerous and sophisticated, the goal of technical sketching is simplifica-tion. Just a couple of pencils, an eraser, and a few sheets of paper should be all that is needed. Many a great design idea was born on the back of a napkin with a No.

This type of sketch is more appropriate for technical illustrations than for design communications. Irwin drawing contest winner Tim Brummett, Purdue University. Although there may be a temptation to use straight-edges, such as T-squares and triangles, a minimum amount of practice should allow you to draw lines good enough for sketches without these aids.

Mechanically drawn lines can slow you down, add a level of accuracy not needed in the early stages of a design, and restrict the types of forms explored. Pencils The lead used in pencils comes in many different hardnesses; the harder the lead, the lighter and crisper the line. For general-purpose sketching, leads in the H and HB range will give you acceptable lines. If the lead is much harder, the lines will be too light and hard to see. In addi-tion, hard lead has a tendency to puncture and tear some of the lighter-weight papers used in sketching.

On the other hand, if the lead is too soft, too much graphite is deposited on the paper and can be smudged easily. Leads in the mid-dle range allow for a dark, relatively crisp line. Eraser Erasing should only be used to correct mistakes in a line, not to make changes in a design.

Such changes should be recorded on a separate sketch, and the original C Figure 2. Still, most people find that a small amount of erasing is helpful.

Usually, the eraser on the end of the pencil is sufficient. However, if you are going to do a lot of sketching, you may need a separate eraser, and one of any size or shape will do. You might consider a gum eraser, since they leave less residue when used.

Paper There is a wide range of paper choices for sketch-ing including a napkin you could draw on during lunch. Because of the difficulty of drawing long lines freehand, paper much larger than that is normally not useful for a single sketch. On the other hand, larger paper is useful for drawing multiple sketches that should be visually grouped together.

Plain bond paper with no lines offers the highest degree of flexibility; lined paper tends to lock you in visually to drawing along the lines. However, when you want the guidance of existing lines on the paper, it is most useful to have the lines running along both dimensions, forming a grid. Two of the most common grid papers used in sketching are square grid Figure 2.

Common grid densities run from 4 to 10 lines per inch. A less common type of grid paper is perspective, which is used to create another type of pictorial sketch Figure 2. Often, it would be useful to have grid lines for the sketch, but not for the final drawing.

One way this can be achieved is to sketch on thin, plain, semitransparent trac-ing paper laid over the grid paper and taped down so that the grid lines show through. When the sketch is done, it is untaped from the grid paper and viewed without the grid lines behind it. This technique is also a money saver because grid paper is more expensive than tracing paper often called trash paper , which can be bought in bulk on rolls.

The other advantage to tracing paper is that it can be laid over other sketches, photos, or finished technical drawings. A light table can be used to improve the tracing process. Tracing is a fast, accurate method for refining a design idea in progress or for using an existing design as the starting point for a new one. The following sections describe common techniques used to produce good sketches quickly.

The discussions cover the tools and the techniques for creating straight lines, curves such as cir-cles and arcs , and proportioned views. With patience and practice, it is possible for you to become good at making quick, clear sketches, regardless of your experience and natural drawing ability. Over a period of time and with practice you will be able to acquire the skills and knowledge necessary to create design sketches.

Sketching is based on seeing perception and visual thinking through a process of seeing, imaging, and representing Figure 2. Seeing is our primary sensory channel because so much infor-mation can be gathered through our eyes. It is our best-developed sense and one we take for granted every day as we easily move through our environment. Seeing empowers us to sketch. Imaging is the process that our minds use to take the visual data received by our eyes to form some structure and meaning.

Representing is the process of creat-ing sketches of what our minds see. Boring in , you can see either the head of an older woman or the profile of a younger woman. The illustration on the right can be viewed as either a vase or two profiles of the same person looking at each other. Figures 2. It is also possible to make sketch-es of objects that cannot exist in the real world.

Escher was a genius at creating sketches and drawings of objects or environments that could not exist in reali-ty Figure 2. Practice Exercise 2. Images often appear spontaneously in response to a memory recall.

Your bedroom where you grew up as a child, or the street you lived on. A close relative, a famous actor, or a close friend from high school.

A basketball sitting at center court on your high school gym floor. Try sketching the basketball on the floor. Your response to these written prompts is an example of your visual memory. You are thinking visually, which is a very powerful way of thinking when designing. Escher Company-Holland. The lines or outlines of an object are used to represent the edges and contours of objects we see in the world. If we sketch the boundaries, an object slowly takes shape and we begin to recognize it as a familiar object.

This technique of sketching the out-line of an object is called contour sketching and is an important technique used by novice sketchers to gain con-fidence in their sketching ability. Contours on objects can take the form of edges of an object, lines that separate contrasting light or color, changes in the surface of an object, and overlapping parts.

The primary reason for con-tour sketching is to develop your visual acuity and sensi-tivity to important object features, which are needed to create accurate sketched representations. When you first learn how to use contour sketching, begin by slowly tracing the outline of an object with your eyes while slowly sketching what you see. At first the sketch may seem crude and out of proportion, but with practice your sketches will be quite good.

Both tech-niques are useful when learning how to observe and cre-ate sketches of what you see. Making a Contour Sketch In this exercise, you are to create a sketch of the stapler shown in Figure 2. Step 1. Using a plain piece of white paper and a soft lead pencil, place your drawing hand with the pencil near the center of the paper.

Step 2. Orient the paper in a comfortable position for sketching. Step 3. Comfortably and in a relaxed manner, very slowly begin to trace the outline of the object with your eyes. Step 4. Slowly move your pencil across the paper as your eyes scan the outline of the object. Do not erase or sketch over lines and do not look at your sketch. Sketch very slowly and deliberately. Step 5. Continue to draw each edge as you view it at a slow and deliberate pace.

Step 6. Look at your sketch after you have finished viewing the contours of the object. This technique is used to improve your sketching ability. In this example, the contour sketch was created without looking at the paper. Making a Modified Contour Sketch In this exercise, you are to create a contour sketch, but you will be able to look at your sketch as you are working Figure 2. Do not erase or sketch over lines. Occasionally look at your sketch to match it with the object being drawn.

Continue to draw each edge and interior edges at a slow and deliberate pace as you view the object. In this technique you concentrate on the spaces In other words, you concentrate on the geometry of the objects, such as lines, curves, angles, and tangencies, and not on the names of the objects, such as handle, hole, base, cube.

An example of a negative space sketch is shown in Figure 2. Notice that the object itself is not shaded and lacks details, but the space surrounding the object is shaded. In this technique you take a photograph of a recognizable object, such as a chair, and turn it upside-down before sketching it. By turning it upside-down you can concentrate on the shape and form of the object, allowing you to create a better sketch. Making a Negative Space Sketch For this exercise, you are to create a negative space sketch of the object shown in Figure 2.

Use a plain sheet of white paper and begin by sketching the box surrounding the object. Sketch over the top of the negative spaces in the figure to reinforce that you are going to be sketching the negative spaces and not the object itself. Focus on one of the outlined negative spaces just created in step 2 until you can visualize the negative space.

Now begin sketching the negative space form on your sheet of paper. Concentrate on drawing lines and curves by determining the angles, lengths, tangencies, and other geometric characteristics. Repeat steps 3 and 4 until all the negative space has been created. Courtesy of Lunar Design Incorporated. Carefully sketch the outline of the object by concentrating on the geometry or form and not the names of the part, such as legs or feet. By doing so you will be able to create a more accurate sketch of the object.

Lines created for sketches differ from mechanically produced lines in that they are not constrained or guided by instruments, such as a T-square, template, or compass.

Instead, the lines are guided strictly by the eye and hand. Such lines have a different aesthetic quality than mechanical lines Figure 2. At a micro level, sketched straight lines are uneven; at a macro level, they should appear to follow a straight path without any interruptions Figure 2. One of the easiest guides to use for sketched lines is grid paper. Lines drawn right on the grid are the easiest to produce, and even those lines that are offset but parallel to a grid line are fairly easy to produce.

The idea is to keep your sketched line a uniform but not necessarily equal distance between two existing grid lines. Curved lines, straight lines not parallel to a grid line, and lines drawn without the aid of a grid are more diffi-cult. In all of these cases, the lines are drawn as interpola-tions between two or more points. Quite often, the sketched line is built up from a sequence of two or three passes with the pencil Figure 2.

The first pass is drawn light, using a hard lead, such as a 4H, sharpened to a point, and may not be as straight as your final line will be; however, it should provide a path on top of which the final, even, darker line is drawn. For particu-larly long lines, the initial line may be drawn in segments, coming from the two endpoints and meeting in the middle; however, the final line should be drawn in one single pass to avoid choppiness.

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If necessary, another pass can be used to darken or thicken the line. Long lines are difficult to control, even for someone with a lot of experience. If you cannot choose a drawing scale that reduces the size of the sketch, use grid paper as a guide, drawing either directly on the grid paper or on tracing paper placed on top of the grid paper.

If the line is parallel and rel-atively close to the edge of the paper, you can rest a finger or a portion of your palm along the edge of the paper to sta-bilize your drawing hand Figure 2. If necessary, you can use a ruler or a scrap of paper to mark a series of points on the sketch, but this will slow you down a bit.

Another technique that helps when drawing lines of any length is changing the orientation of the paper. Sketching paper should not be fixed to your drawing sur-face. Instead, you should be able to rotate the paper freely, orienting it in the direction that is most comfortable. Practice will determine which orientation is best for you. Many people find that drawing the lines by moving away from or toward the body, rather than from left to right, produces the quickest, straightest lines; others find it most comfort-able if the paper is angled slightly away from the body.

Mechanical Sketched Figure 2. The light line is then drawn over and darkened. The following summarizes the techniques used to sketch straight lines: Do not fix the paper to the surface. One technique is to use the edge of the paper as a guide for your hand A. Another technique is to mark equal distances from the edge of the paper using a marked scrap of paper as a guide B.

The marks are then used as a guide to produce the line. Refer to Figures 2. Comfortably and in a relaxed manner, position your hand so that the pencil is close to one of the marked end-points of the first line to be sketched. Sketch the top line first, to avoid smearing newly sketched lines with your hand. Quickly scan the two endpoints of the first line to determine the general direction in which you will be sketching.

Repeat steps 4 and 5 until the other end of the line is reached. Step 7. Return to the starting point of the line and overdraw the line segments with a slightly longer, heavier stroke, to produce a thick, dark, more continuous straight line.

Step 8. Repeat steps 3 through 7 to sketch the remaining straight lines. The most common curve is a circle or circular arc. Although very small circles and arcs can be drawn in one or two strokes and with no guide points, larger circles need some preliminary points. The minimum number of points for a circle is four, marked on the perimeter at equal degree intervals.

For an arc, use at least one guide point for every 90 degrees and one at each end. One way is to draw a square box whose sides are equal to the diameter of the circle Figure 2. The midpoints on each side of the square mark the points where the circle will touch the square. These points are called points of tangency. More guide points can be added by drawing the two diagonals across the square.

The center of the circle being sketched is the point where the diagonals cross Figure 2. Mark the guide points on each diagonal approximately two-thirds the distance from the center of the circle to the corner of the square. This distance is the approximate radius of the circle Figure 2. As with longer straight lines, large arcs and circles are harder to draw and may need guide points marked at more frequent intervals.

To do this, it is handy to use a scrap of paper with the radius marked on it Figure 2. Circular arcs are drawn the same way as circles, adjust-ing the number of points to suit the degree of curvature i. Noncircular arcs, however, can be more difficult. Since these lines are only to be sketched, cal-culating the points that the curve should pass through is too involved and is not recommended.

Simply use the eye to estimate guide points and then gradually draw a curve to pass through those points. Ellipses and curves in multiview drawings are two special cases treated later in this chapter. As with straight lines, positioning the paper and using a relaxed grip are important for helping you create good curves. Unlike straight lines, curves are usually best drawn in a series of arcs of not more than 90 degrees. After each arc is drawn, rotate the paper for the next seg-ment of arc.

With practice you may be able to eliminate rotating the paper for smaller arcs, but you will probably still have to do so for larger ones. Refer to Figure 2. Orient the paper in a comfortable position and relax your grip on the pencil. Lightly mark the corners of a square with sides equal in length to the diameter of the circle or arc to be sketched.

Lightly sketch the square, using short strokes to create the straight lines. Mark the midpoints of the four sides of the square.

This gives you four marks on the perimeter of the circle. Sketch diagonals across the corners of the square. Where the diagonals cross is the center of the circle. Mark the diagonals at two-thirds the distance from the center of the circle to the corner of the square.

Sketch the circle by creating eight short arcs, each between two adjacent marks on the perimeter. Start at any mark and sketch an arc to the next mark on either side of the first one, whichever is most comfort-able for you.

Rotate the paper and sketch the next arc from the last mark you touched to the next mark on the perimeter. Repeat this step until all eight arc segments have been sketched. For smoother sketches, rotate the paper in the opposite direction from the one you used to draw the arc. Overdraw the arcs with a thick, black, more contin-uous line to complete the sketched circle. For small circles, use a square A or multiple center lines B C to guide the construction process.

For large circles, use a scrap of paper with the radius marked on it as a guide D. A proportion is the ratio between any two dimensions of an object. These proportions are represented in the sketch by a series of preliminary lines, which are drawn light and fast, and which may or may not represent the locations of the final lines in the sketch. Their purpose is to form a backbone, a structure inside which the final linework can be drawn.

Construction lines are very light, thin lines used to roughly lay out some of the details of sketches or drawings. Do not try to draw the construction lines to exact lengths since lengths are marked later, either by intersecting lines or short tick marks. Construction lines have two primary features: For example, the construction lines become the paths for the final straight lines.

Points marked by the inter-sections of construction lines guide the drawing of circles. Usually, both of these features are used in creating sketches. Since all the dimensions of a sketch are estimated, groups of construction lines forming boxes and other shapes are an important tool for preserving the shape and proportion of the object and its features as the sketch is developed. Grid paper can be used as a guide in creating construc-tion lines but should not be thought of as a substitute, since the grid does not directly represent the proportions of the object, and there are many more grid lines than there are features on the object.

The goal is to draw con-struction lines on top of the grid to reveal the form of the object. With experience, you may be able to make do with fewer construction lines, but while you are learning how to create properly proportioned sketches, you should use more, rather than fewer, construction lines to guide you.

Each feature has a proportion that can be represented by a series of construction lines.

The following steps describe how to proportion a drawing by breaking it down into its component features. Creating a Proportioned Sketch Step 1. Gage the proportion of the overall size of the object. For the first sketch, use two over-all dimensions of the object: Lightly sketch a box that represents the ratio of these two dimen-sions Figure 2.

This box is called a bounding box because it represents the outer dimensional limits of the feature being drawn. If the object is rectangular in shape, the final linework will follow the perimeter of the bounding box. Inside the first bounding box, draw other boxes to represent the larger features of the object, and within those boxes draw still others to represent the smaller features of the object.

Often, a construction line can be used for more than one box. The final boxes each show the proportions of one feature of the object. Continue to draw bounding boxes until the smallest features of the object have been represented. As you gain experience, you may find that some of these smaller fea-tures need not be boxed; instead, their final lines can be sketched directly.

When all of the features of the object have been boxed, begin sketching the final linework, which is done significantly darker than the construction lines. If there is not enough contrast between the construction lines and the final linework, then the con-struction lines become a distraction.

Make the final lines darker, or the construction lines lighter, or both; however, do not erase your construction lines. One of the most difficult sketching techniques to learn is making a sketch look well proportioned. For example, Figure 2. Proportioning skills will improve with practice. A good rule of thumb is, if the drawing does not look or feel right, it probably is not. In the poorly proportioned monitor in Figure 2.

We live in a three-dimensional 3-D world, and representing that world for artistic or technical purposes is largely done on two-dimensional 2-D media. Although a sheet of paper is technically three-dimensional, the thickness of the paper the third dimension is useless to us. It should be noted that the computer screen is a form of two-dimensional medium, and images projected on it are governed by the same limita-tions as projections on paper. Modern techniques, such as holograms, stereograms, and virtual reality devices, are attempts to communicate three-dimensional ideas as three-dimensional forms.

However, drawings are still the primary tool used for representing 3-D objects. Most projection methods were developed to address the problem of trying to represent 3-D images on 2-D media Figure 2.Sketch a line from point 14 to point 16 and located where the projectors for X and Y intersect.

For smoother sketches, rotate the paper in As with straight lines, positioning the paper and using the opposite direction from the one you used to draw a relaxed grip are important for helping you create good the arc. Probably the easiest way of creating such views is to use a 3-D CAD package to create a model. Therefore, after the marks are made for the sketch the isometric axes. Figure 2. Cancel Save. Symmetry lines are used as an axis of symmetry for a particular view.

The basic criterion is, In Figure 4. Problems Use the gridded problem sheets provided at the end of this Hints for Multiview Sketching section to complete the problems that follow.

This is an example of why and label this new line 22—