Chapter Seven. 2D Drawing Representation


Objectives

After studying the material in this chapter, you should be able to:

1. Represent curved surfaces in multiview drawings.

2. Show intersections and tangencies of curved and planar surfaces.

3. Represent common types of holes.

4. Show fillets, rounds, and runouts in a 2D drawing.

5. Use partial views.

6. Apply revolution conventions when necessary for clarity.

7. Show removed views and projected views.

8. Show right- and left-hand parts.

9. Project curved surfaces by points.

10. Show and label an enlarged detail.

11. Show conventional breaks.



Refer to the following standards:

• ANSI/ASME Y14.3 Multiview and Sectional View Drawings


Photograph of CoWorker robot is made by the iRobot Corporation that is used to provide a mobile telepresence in remote locations.

The CoWorker robot is a 3-high Pentium powered robot that can provide a mobile telepresence in remote locations. The CoWorker is made by the iRobot Corporation. (Courtesy of Sam Ogden/Photo Researchers, Inc.)


Overview

An object with molded plastic parts like the one shown above has curved surfaces on inside and outside corners to make it easier to remove the part from the mold. There are a number of practices for showing curved surfaces in your drawings.

Learning the names of typical features and hole types that are used in part design and how they are represented in drawing views will make it easier for you to communicate about designs and to understand their documentation requirements.

At times, conventional practices are used that are not standard orthographic projections. This is to make it easier to represent or interpret objects in drawings. An example is revolving certain features when it adds to the clarity of the drawing. Another example is showing “breaks” when a part does not fit well on the sheet because of its long shape, or to avoid unnecessary detail.

There is an art to creating drawings that show the information clearly and provide all the detail necessary to manufacture it. People can read drawings most easily when views, dimensions, and lines are placed in logical locations that aid in the reader’s comprehension of the part and the design intent for the part.


Practices for 2D Documentation Drawings

Now that you are familiar with the basics of orthographic projection and visualizing objects from the information presented in orthographic views, you are ready to make and read more complex 2D drawings. Although you might sketch complex designs by hand, it is more likely that you would create these types of drawings using CAD, either as 2D CAD drawings, or as 2D CAD drawings generated from a 3D solid model.

Sometimes, practices used to create drawings with 3D CAD differ from those used to create hand-drawn or 2D CAD drawings. You must understand the standards and practices for creating good drawings even when using 3D CAD. The software will not do everything for you.

Common Manufactured Features

Certain features are a part of many engineering designs. Learning their names and shapes, as shown in Figure 7.1 and detailed in Table 7.1, helps you visualize and communicate about them. Some CAD systems may even have prebuilt features that you can place onto a 3D part to create them quickly.

Figure shows an engineering design created by CAD systems to indicate commonly manufactured features.

7.1 Commonly Manufactured Features

Table 7.1 Common Manufactured Features

Feature

Example

Fillet: A rounded interior blend between surfaces; used, for example, to strengthen adjoining surfaces or to allow a part to be removed from a mold

Image

Round: A rounded exterior blend between surfaces; used to make edges and corners easier to handle, improve strength of castings, and allow for removal from a mold

Image

Counterbore: A cylindrical recess around a hole, usually to receive a bolt head or nut

Image

Countersink: A cone-shaped recess around a hole, often used to receive a tapered screw head

Image

Spotface: A shallow recess like a counterbore, used to provide a good bearing surface for a fastener

Image

Boss: A short raised protrusion above the surface of a part, often used to provide a strong flat bearing surface

Image

Lug: A flat or rounded tab protruding from a surface, usually to provide a method for attachment

Image

Flange: A flattened collar or rim around
a cylindrical part to allow for attachment

Image

Chamfer: An angled surface, used on a cylinder to make it easier to start into a hole, or a plate to make it easier to handle

Image

Neck: A small groove cut around the diameter of a cylinder, often where it changes diameter

Image

Keyway/Keyseat: A shaped depression cut along the axis of a cylinder or hub to receive a key, used to attach hubs, gears, and other parts to a cylinder so they will not turn on it

Image

Knurl: A pattern on a surface to provide for better gripping or more surface area for attachment, often used on knobs and tool handles

Image

Bushing: A hollow cylinder that is often used as a protective sleeve or guide, or as a bearing

Image

Conventional Representationsc

Standard orthographic projections don’t always show complex shapes as clearly and simply as you may wish, so certain alternative practices, referred to as conventions, are accepted. Although “convention” is usually a general term for an accepted method, in the case of technical drawing it refers particularly to a simplified representation that enhances economy and clarity in a drawing. Although conventional representations do deviate from true orthographic projection, their methods of simplification are generally recognized and accepted. (See ASME Y14.3.) In other words, conventions are like rules for breaking the rules.

Intersections and Tangencies

To represent complex objects, multiview drawings use standard methods for depicting the way planar and curved surfaces meet. A plane surface can intersect or be tangent to a contoured surface, as shown in Figures 7.2 and 7.3. When a plane surface intersects the contoured surface, a line is drawn to represent the edge formed by that intersection. When the plane surface is tangent to the contoured surface, no line or a thin phantom line pattern is drawn where the surfaces meet, depending on whether the phantom line is needed to aid in visualization.

Two models on the left and right depict intersecting and tangent surfaces.

7.2 Intersecting and Tangent Surfaces

Eight drawings placed adjacent to each other depict intersecting and tangent surfaces.

7.3 Orthographic Views of Intersecting and Tangent Surfaces

Removed Views

It is not always possible to show all the drawing views in alignment on the sheet. This is particularly true of civil and architectural drawings where the size and complexity of the object make it hard to show the level of detail necessary and still fit the views on one sheet. When this is the case, a removed view can be used. There are two different ways to indicate the viewing direction for removed views. One is to use a view indicator arrow to show the direction of sight, as shown in Figure 7.4a. The other is to use a viewing plane line, as shown in Figure 7.4b. Clearly label the removed view.

Two sheets placed at the top and bottom depict removed views.

7.4 Indicating Removed Views

7.1 Visualizing and Drawing Complex Cylindrical Shapes

The illustrations in Figure 7.5 show how to visualize cylindrical features being cut from a rectangular block (prism). Compare each illustration showing the material being removed with the drawing.

The drawing shows four steps of visualizing and drawing cylindrical shapes.

7.5 Visualizing and Drawing Cylindrical Shapes

In Figure 7.5a there is no line where the contoured surface of the rounded top joins the straight planar sides. The top view appears as a rectangle. The centerline for the rounded top is shown in all three views. Consider these questions as you look at Figure 7.5a:

• In this drawing, how many views are necessary?

• Which views are repetitive?

• Is the centerline required to locate the rounded top?

In Figure 7.5b, the material for the center hole is removed. Then, hidden lines are added to the top and side view showing the limiting elements of the cylindrical hole. As you look at Figure 7.5b note:

• In the front view the hole appears round.

• The centerlines in the drawing locate the hole as well as the rounded top, since they are concentric.

In Figure 7.5c the counterbored holes are created. As you look at Figure 7.5c ask yourself:

• How many lines are used to show the counterbore in the side and top views?

• How many views are necessary?

In Figure 7.5d a portion of the top surface is removed. Notice how those lines appear in the top and side views. How many views are necessary now?

In Figures 7.5a and 7.5b only one view is required.

In Figure 7.5c, the side view or top view or a note specifying the depth of the counterbore is needed. The counterbore is five lines.

In Figure 7.5d the top or side view or a note is required. The side view is probably a better choice, because it shows more about the shape than the top view.

7.2 Cylinders when Sliced

Cylinders are often machined to form plane or other types of surfaces. Figure 7.6a shows a single machined cut that created two normal surfaces. Normal surfaces appear true shape in the view where the line of sight is perpendicular to the surface. In the two other views that normal surface appears on edge. The back half remains unchanged.

Three views of cylinders with Planar Surfaces Cut Away is displayed.

7.6 Showing Views of Cylinders with Planar Surfaces Cut Away

In Figure 7.6b, two stepped cuts form four normal surfaces. Note that surface 7–8 (top view) is through the center of the cylinder, producing in the side view line 21–24 and in the front view surface 11–14–16–15, which is equal in width to the diameter of the cylinder. Surface 15–16 (front view) shows in the top view as 7–8–Arc 4. Surface 11–14 (front view) shows in the top view as 5–6–Arc 3–8–7–Arc 2.

Figure 7.6c shows a part with two coaxial cylindrical features, which is cut to form a normal surface parallel to the axis of the cylinders.


Step by Step: Plotting Curves by Hand

Example 1

Figure shows one type of plotting curves by hand in three steps.

Steps 1–3 apply to both illustrated examples.

Image Given the front and right-side view, project the correct view of the curve into the top view. Break up the curve into several points and locate them in the adjacent view.

Image Project the points along projection lines into the top view from the front view. Transfer the depth from the side view, using the back surface as a reference plane.

Image Draw the curve through the points.

Example 2

Figure shows another type of plotting curves by hand in three steps.

7.3 Cylinders and Ellipses

If a cylinder is cut by an inclined plane, as shown in Figure 7.7a, the inclined surface is bounded by an ellipse. This ellipse will appear as a circle in the top view, as a straight line in the front view, and as an ellipse in the side view. Note that circle 1 appears circular in the top view regardless of the angle of the cut. If the cut is at 45° from horizontal, it would also appear as a circle in the side view.

Three drawings depict elliptical surfaces on cylinders.

7.7 Elliptical Surfaces on Cylinders

When a circular shape is shown inclined in another view and projected into the adjacent view as shown in Figure 7.7b, it will appear as an ellipse, even though the shape is a circle. The inclined ellipse in Figure 7.7c is not shown true size and shape in any of the standard views given. You will learn in Chapter 9 how to create auxiliary views to show the true size and shape of inclined surfaces like these.

7.4 Intersections and Tangencies

Where a curved surface is tangent to a plane surface (Figure 7.8a) no line is drawn, but when it intersects a plane surface, as in Figure 7.8b, a definite edge is formed.

Four drawings depict Intersections and Tangencies.

7.8 Intersections and Tangencies

Figure 7.8c shows that when curves join each other or plane surfaces smoothly (i.e., they are tangent) a line is not drawn to show where they come together. If a combination of curves creates a vertical surface, as in Figure 7.8d, the vertical surface is shown as a line (here in the top view).

When plane surfaces join a contoured surface, a line is not shown if they are tangent, but is shown if they intersect. Figures 7.8eh show examples of planes joining contoured surfaces.

Intersections of Cylinders

Figure 7.9a shows an example of a small cylinder intersecting a large cylinder. When the intersection is small, its curved shape is not plotted accurately because it adds little to the sketch or drawing for the time it takes. Instead it is shown as a straight line.

Four diagrams depict intersections of cylinders.

7.9 Intersections of Cylinders

When the intersection is larger, it can be approximated by drawing an arc with the radius the same as that of the large cylinder, as shown in Figure 7.9b.

Large intersections can be plotted accurately by selecting points along the curve to project, as shown in Figure 7.9c.


Tip

Using CAD tools you can locate the center and points on the major and minor axis and use the CAD software’s ellipse tool to draw the whole ellipse through the points. Then, trim off the extra portion.

A similar technique works when using a template.


When the cylinders are the same diameter, their intersections appear as straight lines in the adjoining view, as shown in Figure 7.9d. When you are using 3D modeling, the accurate intersection of the surfaces is typically represented (see Figure 7.10).

Intersections of cylinders is shown.

7.10 Intersections. (a) and (b) Examples of a narrow prism intersecting a cylinder. (c) and (d) Intersections of a keyseat and cylinder and a small hole and cylinder.


CAD at Work: To Show or Not to Show: Tangent Surfaces in Solid Models

Figure shows a solid model of contoured surfaces that are used to show the tangent edges.
Figure shows the best way to demonstrate the tangent surfaces in the solid models. In the pictorial view, the tangent edges are shown as phantom lines.
Figure shows the fine way to demonstrate the tangent surfaces in the solid models. In the pictorial view, the tangent edges are shown as solid lines.
Figure shows the worst way to demonstrate the tangent surfaces in the solid models. In the pictorial view, when the view is unclear without tangent edges is said to be the worst way.
Illustration shows the front view and top view of the solid model with the fillets and rounds is drawn using the phantom lines to show the tangent edges.
Figure depicts the orthographic view of the solid model.

When you are creating solid models of contoured surfaces, it can be very useful to show the “tangent edges” where the contoured surface intersects the model. These lines that depict where the contoured surface ends and where the planar surface begins are not typically drawn in orthographic drawing views, unless the drawing might be confusing without them. When it is necessary to show the tangent edges, use a phantom line for them.

Using a phantom line to show the tangent edges of the model in the pictorial view is often necessary on parts that have many fillets and rounds; otherwise, the view generated by the software may not show the part clearly.

Most CAD software allows you to set the display of tangent edges both for the entire drawing and for individual views.

Even when you are creating drawings using a CAD system you should follow standard drawing conventions. Knowing your CAD software well is important so that you can manage settings like those for tangent edges to show your drawing clearly.


7.5 Fillets and Rounds

A rounded interior corner is called a fillet. A rounded exterior corner is called a round (Figure 7.11a). Sharp corners are usually avoided in designing parts to be cast or forged because they are difficult to produce and can weaken the part.

Four drawings placed adjacent to each other depict rough and finished surfaces.

7.11 Rough and Finished Surfaces

Two intersecting rough surfaces produce a rounded corner (Figure 7.11b). If one of these surfaces is machined, as shown in Figure 7.11c, or if both surfaces are machined, as shown in Figure 7.11d, the corner becomes sharp. In drawings, a rounded corner means that both intersecting surfaces are rough. A sharp corner means that one or both surfaces are machined. Do not shade fillets and rounds on multiview drawings. The presence of the curved surfaces is indicated only where they appear as arcs, unless it is done to call attention to them.

3D CAD software varies in its ability to create complex blends for fillets and rounds. Figure 7.12 shows a CAD model with complex fillets. Figure 7.13 shows complex 3D CAD rounds.

A 3D CAD model shows a rectangular box with several fillets.

7.12 Fillets on a CAD Model (Courtesy of Ross Traeholt.)

3D CAD model of a three-hole punch is shown.

7.13 Rounds on a CAD Model of a Design for a Three-Hole Punch (Courtesy of Douglas Wintin.)

7.6 Runouts

Small curves called runouts are used to represent fillets that connect with plane surfaces tangent to cylinders, as shown in Figures 7.14ad. The runouts should have a radius equal to that of the fillet and a curvature of about one eighth of a circle, as shown in Figure 7.15c. Figures 7.14en show more examples of conventional representations for fillets, rounds, and runouts.

Runouts are explained.

7.14 Conventional Fillets, Rounds, and Runouts

Three drawings placed adjacent to each other depict runouts.

7.15 Runouts

Runouts from different filleted intersections will appear different owing to the shapes of the horizontal intersecting members. In Figures 7.14e and 7.14f, the runouts differ because the top surface of the web is flat in Figure 7.14e, whereas the top surface of the web in Figure 7.14f is considerably rounded.

When two different sizes of fillets intersect, the direction of the runout is dictated by the larger fillet, as shown in Figures 7.14g and 7.14j.

7.7 Conventional Edges

Rounded and filleted intersections eliminate sharp edges and can make it difficult to present the shape clearly. In some cases, as shown in Figure 7.16a, the true projection may be misleading. There is a conventional way of showing rounded and filleted edges for the sake of clarity. Added lines depicting rounded and filleted edges, as shown in Figures 7.16b and 7.16c, give a clearer representation, even though it is not the true projection. Project the added lines from the intersections of the surfaces as if the fillets and rounds were not present.

Three drawings placed adjacent to each other depict conventional representations.

7.16 Conventional Representation of a Rail

Figure 7.17 shows top views for each given front view. The first set of top views have very few lines, even though they are the true projection. The second set of top views, where lines are added to represent the rounded and filleted edges, are quite clear. Note the use of small Y shapes where rounded or filleted edges meet a rough surface. If an edge intersects a finished surface, no Y shape is shown.

Four set of drawings placed adjacent to each other depict conventional edges.

7.17 Conventional Edges

Figure shows an oval with four slanting lines on either side that are enclosed in a square box.

George Washington Crossing the Delaware as Seen by a Trout (Excerpted from Droodles – The Classic Collection by Roger Price ©2000 by Tallfellow Press. Used by permission. All rights reserved.)

7.8 Necessary Views

What are the absolutely minimum views required to completely define an object?

As you have already seen, sometimes only a single view with a note about the part’s thickness is enough to define the shape (Figure 7.18). Sometimes two views are required (Figure 7.19). For complex parts three or more views may be required (Figure 7.20).

Figure illustrating One-View drawing.

7.18 One-View Drawing

Figure illustrating Tow-View drawing.

7.19 Two-View Drawing

Figure illustrating Three-View drawing.

7.20 Three-View Drawing

In each set of views shown in Figure 7.21, three views are shown, but only two of the three are required.

Five examples showing the unnecessary views being eliminated.

7.21 Three-View Drawings Showing Unnecessary Views Eliminated

When deciding which views to show, keep in mind the following:

• Show sufficient views to completely describe the shape.

• Show the right-hand view instead of the left-hand view if both show the object equally well.

• Choose the top view rather than the bottom view.

• Show long parts horizontally on the sheet for two reasons: (1) they fit better; (2) they tend to appear even longer when shown vertically.

• Make it your goal to communicate the information clearly. If an additional view helps toward this goal, show it. Keep in mind that drawings are easier to read and update if they are simpler, rather than more complex.

7.9 Partial Views

A view may not need to be complete to show what is necessary to clearly describe the object. This is called a partial view and is used to save sketching time and make the drawing less confusing to read. You can use a break line to limit the partial view, as shown in Figure 7.22a, or limit a view by the contour of the part shown, as shown in Figure 7.22b. If the view is symmetrical, you can draw a half-view on one side of the centerline, as shown in Figure 7.22c, or break out a partial view, as shown in Figure 7.22d. The half-views should be the near side, as shown.

Partial views are explained.

7.22 Partial Views

When you are drawing a partial view, do not place a break line where it will coincide with a visible or hidden line, as this may cause the drawing to be misinterpreted.

Occasionally, the distinctive features of an object are on opposite sides. In either complete side view there will be a considerable overlapping of shapes. In cases like this, two side views are often the best solution, as shown in Figure 7.23. The views are partial views, and certain visible and hidden lines have been omitted for clarity.

Partial side views of a drawing is displayed.

7.23 Partial Side Views

Showing Enlarged Details

Figure 7.24 shows drawing details clearly by including detail views drawn at a larger scale. When adding a detail, draw a circle around the features that will be included in the detail as shown in Figure 7.24 (top). Place the detail view on the sheet as you would a removed view. Label successive details with the word DETAIL followed by a letter, as in DETAIL A, DETAIL B, and so on, and note the scale for the detail below its name.

Two drawings placed on the top and bottom shows enlarged details.

7.24 Enlarged Detail

Enlarged details are easy to generate using CAD software.

Conventional Breaks

To shorten the view of a long object, you can use break lines as shown in Figure 7.25. Figure 7.26 shows two views of a garden rake. When the long handle of the rake is shown to scale, the details of the drawing are small and hard to read. Using a break to leave out a portion of the handle allows the scale for the ends to be increased to show the details clearly.

Five drawings placed adjacent to each other depict conventional breaks.

7.25 Conventional Break

Two drawings placed on the left and right depict the use of conventional breaks.

7.26 Conventional breaks allow for increased scale to show detail.

7.10 Alignment of Views

Always draw views in the standard arrangement shown in Figure 7.27 to be sure that your drawings are not misinterpreted. Figure 7.27a shows an offset guide that requires three views. Their correct arrangement is shown in Figure 7.27b. The top view should be directly above the front view, and the right-side view directly to the right of the front view—not out of alignment, as in Figure 7.27c, unless absolutely necessary and then the viewing directions must be clearly labeled in a pictorial view.

Alignment of views for Third-Angle Projection is displayed.

7.27 Alignment of Views for Third-Angle Projection

Never draw the views in reversed positions, with the bottom over the front view or the right side to the left of the front view, as shown in Figure 7.27d. Even though the views do line up with the front view, this arrangement could be misread.

Figure 7.28 shows three views in the correct alignment, but this drawing has a poor choice for the front view. The front view should show the shape of the object clearly. One way to consider this is that the front view shows the most information about the material that would have to be removed from a block.

Three different views are shown.

7.28 Three Views in Correct Alignment but Poor Choice of Front View

After design sketches are completed, you will usually follow them with detailed CAD models and drawings. In CAD drawings, you should apply the same rules for arranging views, clearly depicting the subject of the drawing, using the proper line patterns and lineweights, and following all the necessary standards as used in drawings created by hand.


Tip

Because CAD makes it easy to move whole views, it is tempting to place views where they fit on the screen or plotted sheet and not in the standard or alternative projected arrangement. This is not acceptable, unless you label the viewing direction and show a removed view. Use removed views only when they are really necessary and be sure to label them clearly.


7.11 Removed Views

A removed view is a complete or partial view removed to another place on the sheet so that it is no longer in direct projection with any other view, as shown in the upper left corner of Figure 7.29. A removed view may be used to show a feature of the object more clearly, possibly to a larger scale, or to save drawing a complete regular view. A viewing-plane line is used to indicate the part being viewed. The arrows at the corners show the direction of sight. The removed views should be labeled View A–A or View B–B and so on; the letters refer to those placed at the corners of the viewing-plane line. A view indicator arrow can also be used to show the viewing direction for the removed view, as shown in Figure 7.30. Be sure to label the removed view clearly and provide its scale if it is different from the overall drawing scale.

Removed view is explained. View A-A is marked.

7.29 Removed View Using Viewing-Plane Line

Two drawings placed on the left and right depict the use of view indicator arrow.

7.30 Removed View Using View Indicator Arrow

Architectural drawings often cannot fit even two standard views on the sheet. The sheets are typically labeled to indicate the standard views, as in Figure 7.31. Views are labeled, for example, “Plan” for the top view, “East Elevation” for the side view seen from the east compass direction, and so forth. Additional views use a viewing-plane line or arrow to indicate the direction of sight.

Architecture drawing of a house.

7.31 Architectural Drawing with Views Labeled (Courtesy of CH2M HILL.)

In large civil drawings and other complex drawings such as the electrical drawing in Figure 7.32, one entire view may not be able to be shown clearly on a single sheet. For projects that extend sheet to sheet, match lines are often drawn showing how one sheet matches to the previous one.

Figure shows a Portion of a Building System Electrical Drawing Using Match lines.

7.32 A Portion of a Building System Electrical Drawing Using Match Lines (Courtesy of CH2M HILL.)

7.12 Right-Hand and Left-Hand Parts

Often, parts function in pairs of similar opposite parts, but opposite parts can rarely be exactly alike. For example, the right-front fender of an automobile cannot be the same shape as the left-front fender. A left-hand part is not simply a right-hand part turned around; the two parts are mirror images and are not interchangeable.

On sketches and drawings a left-hand part is noted as LH, and a right-hand part as RH. In Figure 7.33a, the part in front of the mirror is a right-hand part, and the image shows the left-hand part. No matter how the object is turned, the mirror image will show the left-hand part. Figures 7.33b and c show left-hand and right-hand drawings of the same object.

Right-hand and left-hand parts are explained.

7.33 Right-Hand and Left-Hand Parts

Ordinarily you draw only one of two opposite parts and label the one that is drawn with a note, such as LH PART SHOWN, RH OPPOSITE. If the opposite-hand shape is not clear, you should make a separate sketch or drawing to show it clearly and completely.

7.13 Revolution Conventions

Regular multiview projections are sometimes awkward, confusing, or actually misleading. For example, Figure 7.34a shows an object that has three triangular ribs, three holes equally spaced in the base, and a keyway. The right-side view is a regular projection, but is not recommended—the lower ribs appear in a foreshortened position, the holes do not appear in their true relation to the rim of the base, and the keyway is projected as a confusion of hidden lines.

Six drawings placed adjacent to each other depict revolution conventions.

7.34 Revolution Conventions

The method shown in Figure 7.34c is preferred because it is simpler to read and requires less time to sketch. Each of the features mentioned has been revolved in the front view to lie along the vertical centerline, from which it is projected to the correct side view.

Figures 7.34d and 7.34e show regular views of a flange with several small holes. The hidden holes are confusing and take unnecessary time to show. Figure 7.34f shows the holes revolved for clarity.

Figure 7.35 shows a regular projection with a confusing foreshortening of its inclined arm. In Figure 7.35b, the lower arm is revolved to line up vertically in the front view so that it projects the true length in the side view and makes the object’s symmetry clear.

Three drawings placed adjacent to each other depict revolution conventions.

7.35 Revolution Conventions

Revolutions like these are frequently used in connection with sectioning. Revolved sectional views are called aligned sections.

In views generated from 3D CAD models, revolving the features to show their true size is not required, but it is preferred, especially in hand-drawn and 2D CAD drawings.

Common Hole Features Shown in Orthographic Views

Orthographic views of common hole features are shown in Figure 7.36. See Table 7.1 on page 286 for descriptions of these common hole features.

Orthographic views of common hole features are displayed.

7.36 Representing Holes in Orthographic Views; Dimensions for (a)–(e) in Metric, (h)-(j) in Inches

Common Features Shown in Orthographic Views

Orthographic views of common features are shown in Figure 7.37. See Table 7.1 on page 286 for descriptions of common features.

Common features in Orthographic Views are displayed.

7.37 Representing Common Features in Orthographic Views


Portfolio

Figure shows the portfolio in an orthographic view of a solenoid valve manifold.

Orthographic Views of a Solenoid Valve Manifold. This drawing is for a part that has many intersecting holes. (Courtesy of Wood’s Power-Grip Co., Inc.)

Figure shows the architecture drawing of the typical portfolio projection that are viewed in differenct elevations.

The views in this architectural drawing are too large to fit on a sheet in typical projection, so removed views are used. Notice that each view is clearly labeled as to its direction of sight, since the views are not in projection. (Courtesy of Locati Architects.)


Key Words

Boss

Bushing

Counterbore

Countersink

Chamfer

Fillet

Flange

Intersect

Keyway/Keyseat

Knurl

Left-Hand Part

Lug

Neck

Partial View

Removed View

Revolutions

Right-Hand Part

Round

Runouts

Spotface

Tangent

Chapter Summary

• Irregular curves can be plotted by identifying points on the object. The points can be projected to approximate the boundaries of the curved surface.

• Drawing conventions define usual practices for the representation of features such as holes, bosses, ribs, webs, lugs, fillets, and rounds.

• Use the same main practices to arrange drawing views on the sheet for both hand-drawn and CAD drawings. Show and label enlarged details and removed views. Use partial views and leave out hidden lines as long as the object is shown clearly.

• When curved and planar surfaces intersect, an edge is formed that is represented by a line in the drawing. When curved and planar surfaces are tangent, no edge is formed, so no line is needed. If the drawing is not clear without it, use a phantom line to show tangencies.

• Common types of holes are through, blind, countersunk, counterbored, and spotfaced.

• Fillets, rounds, and runouts are special types of tangent contours formed on parts with rounded edges.

• When necessary for clarity, features are sometimes shown in a revolved position using revolution conventions.

• Break lines can be used to leave out a section of a part where it is uniform or repetitive. Often, this is done to enlarge the scale of the remaining portions of the part so that details can be seen clearly.

Review Questions

1. If the top view of an object shows a drilled through hole, how many hidden lines will be necessary in the front view to describe the hole? How many if the hole is countersunk? Counterbored?

2. If a plane surface intersects a contoured surface, should you show a line in the drawing to represent that intersection? What about when the plane is tangent?

3. What is a fillet? A round? A lug? A boss? Knurling?

4. How do you show right-hand and left-hand parts?

5. Which is easier, creating an enlarged detail by hand or using a CAD system?

Chapter Exercises

Illustration shows missing view problems.

Exercise 7.1 Missing-View Problems. Sketch or draw the given views, and add the missing view. These exercises are designed to fit on 8.5″ × 11″ A-size or A4 metric size paper. Use a title block or title strip as assigned by your instructor. If dimensions are required, study Chapter 11 and use metric or decimal-inch dimensions as assigned by your instructor. Move dimensions to better locations where possible.

Figure shows an isometric projection of a support rod with its dimensions marked.

Exercise 7.2 Rod Support*

Figure shows an isometric view of a Tailstock, with its dimensions labeled.

Exercise 7.3 Tailstock*

Figure shows an isometric view of a linear bearing, with its dimensions labeled.

Exercise 7.4 Bearing*

Figure shows an isometric projection of a rectangular holder clip with its dimensions labeled.

Exercise 7.5 Holder Clip*

Figure shows an isometric projection of a Cam.

Exercise 7.6 Cam*

Figure shows Index Arm drawing in CAD.

Exercise 7.7 Index Arm*

Figure shows Roller Lever.

Exercise 7.8 Roller Lever*

Figure shows the drawing of Support in CAD.

Exercise 7.9 Support*

Figure shows the side view of locating finger.

Exercise 7.10 Locating Finger*

Figure shows the drawing of Toggle lever.

Exercise 7.11 Toggle Lever*

Figure shows the drawing of Cut-off Holder.

Exercise 7.12 Cut-off Holder*

Figure shows the Index Slide.

Exercise 7.13 Index Slide*

Figure shows a side view of Frame Guide.

Exercise 7.14 Frame Guide*

Figure shows the drawing of Chuck Jaw.

Exercise 7.15 Chuck Jaw*

Figure shows the front and bottom views of Hinge Bracket.

Exercise 7.16 Hinge Bracket.* Given: Front and bottom views. Required: Front, top, and right-side views.

Figure shows the front and left side view of Tool Holder.

Exercise 7.17 Tool Holder.* Given: Front and left-side views. Required: Front, top, and right-side views.

Figure shows Shifter Block with Front and left side view.

Exercise 7.18 Shifter Block.* Given: Front and left-side views. Required: Front, top, and right-side views.

Figure shows the side view drawing of Crossfade stop.

Exercise 7.19 Cross-feed Stop*

Figure shows front and left side views of Cross Cam.

Exercise 7.20 Cross Cam.* Given: Front and left-side views. Required: Front, top, and right-side views.

Figure shows drawing of Roller stud.

Exercise 7.21 Roller Stud*

Figure shows the drawing of Hinge Block.

Exercise 7.22 Hinge Block*

Figure shows Feed Rod Bearing.

Exercise 7.23 Feed Rod Bearing*

Figure shows half-size drawing of Lever hub.

Exercise 7.24 Lever Hub.* Draw half size.

Figure shows Vibrator arm.

Exercise 7.25 Vibrator Arm*

Figure shows a front view of the Clutch Lever.

Exercise 7.26 Clutch Lever*

Figure shows Counter Bearing Bracket.

Exercise 7.27 Counter Bearing Bracket.* Draw half size.

Figure shows the drawing of Tool Holder.

Exercise 7.28 Tool Holder*

Figure shows the engineering drawing of Control Block.

Exercise 7.29 Control Block*

Figure shows the drawing of Socket Bearing.

Exercise 7.30 Socket Bearing*

Figure shows the drawing of Tool Holder.

Exercise 7.31 Tool Holder*

Figure shows front view drawing of Locating V-block.

Exercise 7.32 Locating V-Block*

Figure shows the front view drawing of Anchor Bracket.

Exercise 7.33 Anchor Bracket*

Figure shows the drawing of Lead screw bracket.

*Sketch or draw necessary views. These exercises are designed to fit on 8.5″ × 11″ A-size or A4 metric size paper. Use a title block or title strip as assigned by your instructor. If dimensions are required, study Chapter 11 and use metric or decimal-inch dimensions as assigned by your instructor. Move dimensions to better locations where possible.

Exercise 7.34 Lead Screw Bracket.** Draw half size.

Figure shows the drawing of lever bracket from both top and bottom.

Exercise 7.35 Lever Bracket.** Draw half size.

**Sketch or draw necessary views. Larger and more detailed parts show the details more clearly when drawn on larger sheet sizes. Consider using B, C, or A3 or A2 sheets. Use a title block or title strip as assigned by your instructor. If dimensions are required, study Chapter 11 and use metric or decimal-inch dimensions as assigned by your instructor. Move dimensions to better locations where possible.

Figure shows the side view drawing of Gripper rod center.

Exercise 7.36 Gripper Rod Center*

Figure shows the drawing of Bearing bracket.

Exercise 7.37 Bearing Bracket*

Figure shows the drawing of Bearing bracket.

Exercise 7.38 Link Arm Connector.* Draw one-quarter size.

Figure shows a side view of the mounting bracket.

Exercise 7.39 Mounting Bracket*

Figure shows LH sifter fork.

Exercise 7.40 LH Shifter Fork*

Figure shows the side view of Gear shift bracket.

Exercise 7.41 Gear Shift Bracket*

Figure shows Fixture Base Drawing.

Exercise 7.42 Fixture Base*

Figure shows Ejector Base drawing in half size.

Exercise 7.43 Ejector Base.* Draw half size.

Figure shows Tension Bracket.

Exercise 7.44 Tension Bracket*

Figure shows Offset bearing drawing.

Exercise 7.45 Offset Bearing*

Figure shows the drawing of Feed Guide.

Exercise 7.46 Feed Guide*

Exercise 7.47 Feed Shaft Bracket. Given: Front and top views. Required: Front, top, and right-side views, half size.*

Figure shows front and top views of Feed shaft bracket.

Exercise 7.48 Trip Lever. Given: Front, top, and partial side views. Required: Front, bottom, and left-side views, drawn completely.*

Figure shows Trip Lever with Front, top, and partial side views.

*Sketch or draw necessary views. Larger and more detailed parts show the details more clearly when drawn on larger sheet sizes. Consider using B, C, or A3 or A2 sheets. Use a title block or title strip as assigned by your instructor. If dimensions are required, study Chapter 11 and use metric or decimal-inch dimensions as assigned by your instructor. Move dimensions to better locations where possible.

Figure shows Electronics Enclosure drawing with orthographic views for the sheet metal electronics mount.

Exercise 7.49 Electronics Enclosure. Create a drawing with the necessary orthographic views for the sheet metal electronics mount.

Figure shows Gyroscope base by Creating a drawing with orthographic views.

Exercise 7.50 Gyroscope Base. Create a drawing with the necessary orthographic views.

Figure shows the drawing of Pry Bar.

Exercise 7.51 Pry Bar. Create a drawing with the necessary orthographic views for the pry bar.

Collage of 4 pictures of an ice cube tray, with 3-dimensional views of top and rear and section views showing the interior parts for better illustration and its dimensions are labeled.

Exercise 7.52 Ice Cube Tray. Create a drawing showing the necessary orthographic views of the ice-cube tray.

Collage of 3 pictures representing different views of a simple knob with its dimensions labeled.

Exercise 7.53 Simple Knob. Create a drawing showing the necessary orthographic views of the knob.

Figure shows the drawing of Wall Hanger.

Exercise 7.54 Wall Hanger. Create a drawing showing the necessary orthographic views of the wall hanger. If assigned, create a 3D model and generate the drawing views from the model.

Figure shows Knurl Bracket Bearing.

Exercise 7.55 Knurl Bracket Bearing. Given: Front and left-side views. Required: Take front as top view on new drawing, and add front and right-side views (Layout B–3 or A3–3).*

*Draw or sketch necessary views. Use metric or decimal-inch dimensions as assigned by the instructor.

Figure shows Horizontal Bracket for broaching.

Exercise 7.56 Horizontal Bracket for Broaching Machine. Given: Front and top views. Required: Take top as front view in new drawing; then add top and left-side views (Layout C–4 or A2–4).*

Figure shows Boom swing bearing for a Power Crane.

Exercise 7.57 Boom Swing Bearing for a Power Crane. Given: Front and bottom views. Required: Front, top, and left-side views (Layout C–4 or A2–4).*

Figure shows Power Feed Bracket for Universal Grinder.

Exercise 7.58 Power Feed Bracket for Universal Grinder. Given: Front and right-side views. Required: Front, top, and left-side views, full size (Layout C–4 or A2–4).*

Set of two figures.

Exercise 7.59 Sliding Nut for Mortiser. Given: Top and right-side views. Required: Front, top, and left-side views, full size (Layout C–4 or A2–4).*

*Draw or sketch necessary views. If dimensions are required, study Chapter 11 and use metric or decimal-inch dimensions as assigned by the instructor.

Exercise 7.60 Create a set of orthographic views generated from a solid model for the part shown. Change the overall width of the part from 3.18 to 3.75 inches. Change the angle from 120 to 135 degrees. Keep the remaining dimensions as given.

Figure shows the orthographic drawing of a 3-dimensional object.

Exercise 7.61 Create a set of orthographic views generated from a solid model for the decorative corner cap part. Change the hole diameters from .125 to .1625. Change the spherical diameter to 1.25.

Figures show the orthographic projections of a solid model - decorative corner cap part.

Exercise 7.62 Carefully consider which feature to use as the base feature and how you will create the model for the hand weight so it will update as specified. Determine the weight if this part is cast from ASTM class 20 gray iron. Update the model to create a set of three hand weights of different weights, but maintain the diameter and length of the crossbar grip. Create a set of orthographic views generated from your solid models for each of the three hand weights.

3D model of a hand weight is shown along with its front view and side view.

Exercise 7.63 Model the part so that as the overall height, width, depth of the part are changed the other features are updated proportionally to them. Before starting, carefully consider which feature to use as the base feature and how you will create the model so it will be updated as specified. Create a set of orthographic views generated from the solid model for the part as shown. Update the part so the overall height is 6.5″, the overall width is 2.5″ and the depth is 2.25″. Produce a second set of orthographic views showing the updated part.

Figure shows the orthographic drawing of a 3-dimensional object.

Exercise 7.64 Create a constraint-based model of the first configuration, save the part, then edit the part to create the second configuration shown. Before starting, carefully consider which feature to use as the base feature and how you will create the model so it will update as specified. Save all part files. Create a set of orthographic views generated from the solid model for each version of the geneva gear.

3D model of a Geneva cam is shown along with its different view drawings.

Exercise 7.65 Create a constraint-based model of the first configuration, save the part, then edit the part to create the second configuration shown. Before starting, carefully consider which feature to use as the base feature and how you will create the model so it will be updated as specified. Save all part files. Create a set of orthographic views for each version of the part.

3D model of a brace is shown. Five view drawings of the model are shown along with the model.
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