Study Unit Auxiliary Views This sneak preview of your study material has been prepared in advance of the book's actual online release.
iii Preview You re entering now into another subject area in your step-by-step quest for drafting proficiency. You re beginning your study of auxiliary views. An understanding of how to use auxiliary views is essential to your complete training. Auxiliary views are used to show the true size and shape of surfaces that aren t parallel to any of the six principal views. A surface feature that s not perpendicular to the line of sight is said to be foreshortened, or shorter than true length. A foreshortened view fails to clearly or accurately represent the feature. On a drawing, an auxiliary view allows you to look directly at an inclined surface so you can view the surface in its true size and shape. Normally, the information needed from the auxiliary view involves the inclined surface only; depicting the other areas of the object typically won t add any clarity to the drawing. However, each drafting object must be considered separately. The standard for auxiliary view presentation can be found in the document Multi and Sectional View Drawings (ANSI Y14.3), published by the American National Standards Institute. Your study unit, Auxiliary Views, consists essentially of several drafting assignments. You re to complete these assignments on the plates contained in the corresponding exam booklet. In effect, as you work through the study unit, you ll be completing your exam. When you complete this study unit, you ll be able to Use the reference plane method to construct auxiliary views Explain the difference between primary and secondary auxiliary views
v Contents DRAWING AN AUXILIARY VIEW....................... 1 Exam Plate E1: Auxiliary Views A Exam Plate E2: Auxiliary Views B MULTIPLE AUXILIARY VIEWS......................... 10 Exam Plate E3: Auxiliary Views C Inspecting Your Work LEARNING CHECK ANSWERS........................ 17
1 Auxiliary Views DRAWING AN AUXILIARY VIEW FIGURE 1 How would you lay out this spar clip in an orthographic projection? Right now, you may be confused about how to accurately depict the slanted surfaces containing holes. By using primary auxiliary views, however, you can solve this problem simply and directly. Look at the airplane s spar clip shown as an isometric pictorial in Figure 1. At first, it may seem extremely difficult to lay out this object in an orthographic projection. However, a drafter who understands the basic principles of auxiliary views could complete the orthographic projection fairly easily. With practice, creating such projections will become easy for you as well. In fact, once you know how to make auxiliary views, you should be able to draw just about any object, given enough information about the object s shape. Exam Plate E1: Auxiliary Views A Your assignment for Exam Plate E1 will be to complete an auxiliary view depicting an object s slanted surface. Figure 2 shows a pictorial and two complete views of the object, called an angle stop. Taking a Closer Look The view of the angle stop on the far left in Figure 2 is the left-side view. The view next to it is the front view of the angle stop. A hole has been machined through the upper part of the object. A slot was added to this hole to form a keyway. In the left-side view, the upper portion of the angle stop is depicted with foreshortened lines because of the slanted surface. The circular hole thus appears as an ellipse in the left-side view.
2 Auxiliary Views FIGURE 2 Your assignment is to complete a primary auxiliary view of the angle stop s slanted portion. The left-side and front views of the angle stop are shown here next to the pictorial. Actually, it would be a common practice in industry to not draw the upper portion of the angle stop at least not as it s shown in the object s leftside view. A foreshortened view of that surface isn t necessary for accurately describing the object. In fact, the foreshortened view would be difficult to draw without an ellipse template, and if drawing it doesn t contribute to an accurate shape description there s no reason for a drafter to spend valuable time drawing the foreshortened view. However, the inclined surface includes special features, such as the hole and keyway. Without a true view of this inclined surface, the object s shape description would be incomplete. Showing that surface in its true size and shape clearly calls for an auxiliary view. Now, from which regular orthographic view should you project the true view of the slanted surface? To establish an accurate auxiliary view, you must project at right angles to the view. Thus, you ll need to project off the front view s version of the inclined surface. In completing your drafting plate, you ll then use the reference plane method to transfer dimensions. Completing the View Step 1: Lay out your drawing on Exam Plate E1. Tape Exam Plate E1 to your drafting board so that the title block is at the bottom. Referring to Figure 2, lay out the left-side view and front view of the angle stop. Use light pressure for this preliminary layout.
Auxiliary Views 3 FIGURE 3 Here is shown the layout of the left-side view, the front view, and the reference planes (RP). Step 2: Add the reference planes. Make one reference plane (which is sometimes also called a reference line) parallel to the inclined surface shown in the front view. Draw this reference plane 3 in. up from the front view. Draw the other reference plane so that it passes through the center of the holes shown in the left-side view. Label both reference planes RP. Your drawing should now look something like what s shown in Figure 3. The only difference is that the upper portion of the angle stop will be broken off and not shown in your drawing. (Your auxiliary view will show this portion of the object.) Step 3: Project limits for your auxiliary view up from the front view. Draw a light projection line from each edge of the inclined surface up through and slightly beyond the reference plane. Later, you ll mark off these projection lines with dimensional points. Step 4: Refer to the left-side view to get the depth dimensions for the auxiliary view. By looking at the left-side view, you can determine the depth dimensions for the drawing. (In fact, any primary orthographic view that s projected from a front view can be used to determine the true depth of the object.) Using your dividers, transfer the depth dimensions from the leftside view to the projection lines. At this point, your drawing should look like what s shown in Figure 4, except for the labels D1, D2, and D3. These labels are
4 Auxiliary Views FIGURE 4 The auxiliary view can be projected up from the slanted surface in the front view as shown here. included in Figure 4 to show you exactly how each depth dimension is transferred. On your drawing, though, you should have no labeled dimensions. In addition, the upper portion of the angle stop won t appear in your drawing as it s shown in Figure 4. Your auxiliary view will show that part of the object. Step 5: Complete the auxiliary view. To complete the light-line construction of the auxiliary view, join all the points together. Add the correctly curved edges and the keyway. Specifications for these features are given on the pictorial in Figure 2. Note in Figure 5 that the upper part of the object appears to have been broken away from the left-side view. This part of the object is effectively represented in the auxiliary view. Completing a second view of this slanted surface would serve no useful purpose here; it would actually be a waste of drafting time. Step 6: Finish the drawing. Darken the outlines of the views with your 2H lead. Make sure you conform to the standards for drawing visible lines. The hidden lines, centerlines, and reference plane lines should be darkened with your 4H lead. Make the title of Exam Plate E1 Auxiliary Views A.
Auxiliary Views 5 FIGURE 5 Once the auxiliary view is added to the partial left-side view and the top view, the shape description of the object is complete. Exam Plate E2: Auxiliary Views B For your next drafting assignment, you ll practice laying out and drawing an auxiliary view of an inclined surface without the aid of a pictorial. Now, you ll use only the information given in the two orthographic views. Usually, these are similar to the conditions under which you ll be working on an actual job. Often, you ll have only a minimum of information from which to start your drawing. As a result, you must continually develop your powers of visualization. Always study every detail of your instructions and reading assignments. By now you may be impressed with the amount of knowledge you need to be a successful drafter. This knowledge, though, can be learned readily because each of your lessons each new thing that you learn builds on what you ve learned previously. The more you learn, the more you become capable of learning. Taking a Closer Look As already mentioned, your assignment here is to complete an auxiliary view based on two existing orthographic views. Figure 6 shows two regular orthographic views a front view and a top view of an object called an anchor lug. On Exam Plate E2, you re to draw this anchor lug. You ll be using an auxiliary view to represent the slanted surface that s currently a part of the top view.
6 Auxiliary Views FIGURE 6 Your job here is to draw the anchor lug, including a complete auxiliary view of the slanted surface. On your drawing, therefore, you won t need to show the hole and the object s rounded end as part of the top view. Completing the View Step 1: Set up Exam Plate E2. Tape Exam Plate E2 to your drafting board so that the title block is at the bottom. Refer to Figure 7 for your step-by-step instructions. Step 2: Lay out the front view. Refer to block 1 of Figure 7. Use the 3 4 and 2 1 4 dimensions to orient your front view on the drafting plate. Lay out the front view of the anchor lug with your 4H lead. You may darken the front view now, or you may wait until your drawing is complete and then darken all the views at once. Some drafters like to darken the views after the layout is complete. (Smearing may sometimes result if the views are darkened during construction.)
Auxiliary Views 7 FIGURE 7 Here is a four-part sequence showing how your drawing should develop.
8 Auxiliary Views Step 3: Lay out the top view. Refer to block 2 of Figure 7. Note that the top view is positioned so that its bottom edge is 2 1 2 from the upper left corner of the front view. Using the specifications shown on Figure 6, complete the top view. Break away the right side of the view as shown in Figure 7, block 2. If you tried to draw the hole and the object s rounded end as part of the top view, you would need to draw elliptical curves. As mentioned previously, drawing such foreshortened views is time consuming and often serves no useful purpose. Therefore, simply sketch a break line across the top view to indicate where the slanted part of the anchor lug had been broken away. Step 4: Add the reference planes. Add the reference plane for the auxiliary view 2 1 2 away from the front view. As shown in Figure 7, block 2, this reference plane is parallel to the angular surface in the front view. Add the auxiliary reference plane through the center of the top view as shown in Figure 7, block 2. Label both reference planes RP. Step 5: Transfer the limits for your auxiliary view. Refer to Figure 7, block 3. With your 4H lead, draw projection lines from the top view into the broken-away area as indicated. With your dividers, transfer the dimensions d1 and d2 from the top view to the auxiliary view. Use these transferred dimensions to draw construction lines as shown in Figure 7, block 3. Step 6: Transfer the depth dimensions to complete the auxiliary view. Refer to Figure 7, block 4. Transfer dimensions d3, d4, d5, and d6. Connect the points to reveal the outline of the auxiliary view. Draw the full radius arc with your compass. Note that this arc takes up the full depth of the view. Draw the 1 diameter circle with your circle template. Step 7: Finish the drawing. Darken in the views as required. When you re finished with the drawing, your completed problem should look similar to what s shown in Figure 8. You don t need to erase your construction lines if they re very light. Construction lines are often difficult to erase when they re in or around an object; therefore, they should always be drawn very light with a 4H or 6H lead. The title of Exam Plate E2 is Auxiliary Views B.
Auxiliary Views 9 FIGURE 8 This is how your completed drawing should appear on Exam Plate E2. On your exam plate though, the drawing will be oriented so that the auxiliary view is in the top left corner of the plate. Now, take a few moments to review what you ve learned about drawing an auxiliary view by completing Learning Check 1. Learning Check 1 At the end of each section of Auxiliary Views, you ll be asked to check your understanding of what you ve just read by completing a Learning Check. Writing the answers to these questions will help you review what you ve learned so far. Please complete Learning Check 1 now. Indicate whether each of the following statements is True or False. 1. In a finished drawing, the auxiliary view must be displayed along with the foreshortened view and the reference planes. 2. If the bottom view of an object is projected from the front view, you can use the bottom view to establish the true depth of the object. 3. The visible lines in an auxiliary view should be darkened with 2H lead, while the hidden lines should be darkened with 4H lead. 4. All the views in a drawing each primary orthographic view and any auxiliary views must be darkened at the same time. Check your answers with those on page 17.
10 Auxiliary Views MULTIPLE AUXILIARY VIEWS Exam Plate E3: Auxiliary Views C Sometimes, it may not be possible to reveal the true size and shape of an object using only one auxiliary view. Look, for example, at surface 1-2-3-4 in Figure 9. In each of the six principal orthographic views, this inclined surface would be foreshortened. Normally, a single auxiliary view set in a plane parallel to the inclined surface is all you would need to describe the shape of that surface accurately. However, in this situation, all the edges of the inclined surface are also foreshortened in the principal orthographic views. To project an auxiliary view of an inclined surface, you need to start from at least one edge drawn to the proper (true) length. In Figure 9, a primary auxiliary view has been constructed to display the surface as an edge. In this primary auxiliary view, note that points 1, 2, 3, and 4 appear as a line, or edge view, of the inclined surface. Once that auxiliary edge view had been established, dimensional points were projected onto a secondary auxiliary view. Thus, both auxiliary views a primary and a secondary are necessary to display the true size and shape of the entire inclined surface. FIGURE 9 Secondary auxiliary views are projected from primary auxiliary views.
Auxiliary Views 11 FIGURE 10 To produce an accurate shape description of the shaft bracket shown here, you ll need to create two auxiliary views. Both views, however, will be primary auxiliary views. However, a second auxiliary view on a drawing isn t necessarily a secondary auxiliary view. Because they have more than one inclined feature, some objects require more than one auxiliary view. In this assignment, you ll complete a drawing of an object in which two auxiliary views are needed to complete the object s shape description. Both of these views will be primary auxiliary views. Some complicated objects require a dozen or more primary views (or portions of views) to create a complete shape description. Figure 10 shows a pictorial view of the shaft bracket you ll be drawing on Exam Plate E3. Separate auxiliary views will be necessary to describe the two inclined surfaces that are part of this object. If you can visualize the principal orthographic views of this bracket, however, you can see that the required edge views of the two surfaces already exist in the regular orthographic projection. Thus, you won t need to create primary and secondary auxiliary views to draw this object. Remember, a primary auxiliary view is projected directly from one of the six principal orthographic views; a secondary auxiliary view is projected from a primary auxiliary view. Taking a Closer Look Now, let s take a closer look at the shaft bracket shown in Figure 9. The bracket consists of three distinct geometric shapes: A round, straight piece 2 1 4 long and with a 2 1 4 diameter A lug shaped like a two-pronged fork and set in an inclined surface angled up 30 A lug with a full radius on its end and also set in an inclined surface, but angled down 30
12 Auxiliary Views FIGURE 11 Shown here is the layout of the top and front views of the shaft bracket. The foreshortened views of the two lugs have been broken away from the top view. If you were to lay out the top view and front view of the object, your drawing would look similar to what s shown in Figure 11. Note that the lugs are broken away in the top view. The two lugs would be foreshortened in that view, and drawing them in that way would contribute little to an accurate shape description. In the front view, the inclined surface on each side begins 1 3 8 from the centerline of the 2 1 4 D piece in the middle. Do you see how a complete shape description of this object will require two primary auxiliary views? Each lug requires a separate auxiliary view. Completing the Views Step 1: Lay out the top and front views on Exam Plate E2. Tape Exam Plate E3 to your drafting board so that the title block is at the bottom. Center the views on the sheet, and refer to Figures 10 and 11. Place the centerline of the top view (serving here as a reference plane) 1 1 2 from the top border. Place the lower edge of the front view 1 1 4 from the bottom border. Step 2: Complete the two views and add the reference planes. Note that the dimensions in the pictorial are for layout information only. Don t include them on your drawing. The distance to the reference planes are indicated in Figure 12.
Auxiliary Views 13 The reference planes are drawn parallel to the inclined surfaces. The distance to a parallel reference plane is determined by the nature of the object and the size of the drawing. In this case, a 1 3 8 space above the left-hand lug and a 1 3 8 space below the righthand lug provide sufficient room for the auxiliary views. FIGURE 12 Once the reference planes are added, your drawing should appear as shown here. Step 3: Lay out the left and right auxiliary views. Show only the true size and shape of the inclined surfaces. Provide break lines for each auxiliary view in a way similar to how it was done in the top view. When you re done laying out the auxiliary views, your drawing should look similar to what s shown in Figure 13. Step 4: Finish the drawing. When you re finished with your light-line construction, darken the views. Use a 2H lead in the compass for your compass lines. Follow all the standards for creating drafting lines. Never let up on quality. Quality lines and lettering may be your ticket to a good job in the future. The title of Exam Plate E3 is Auxiliary Views C.
14 Auxiliary Views FIGURE 13 Your light-line construction, including both of the primary auxiliary views, should appear as shown here. Inspecting Your Work After you ve finished your exam plates, inspect your work by considering the following points. Do you have any dimensions that don t belong on the finished drawings? If you do, make the necessary corrections. Are all your lines correctly drawn? Fix any lines that don t conform to the standards. Did you apply enough pressure for color to penetrate into the fibers of the paper? Even a black line may be dark only on the surface of the drawing paper. If the drawing was to get reproduced, this surface layer of graphite can wear away, leaving behind a weak line. Check the overall appearance of your work. Are your drawings free from smudging? Now, take a few moments to review what you ve learned about drawing multiple auxiliary views by completing Learning Check 2.
Auxiliary Views 15 Learning Check 2 Indicate whether each of the following statements is True or False. 1. One auxiliary view can be projected from another. 2. A primary auxiliary view is projected directly from one of the six principal orthographic views. 3. To ensure that your drawing has an overall neat appearance, you should always space reference planes at least 1 away from the parallel inclined surfaces. 4. A single drawing could have several auxiliary views. Check your answers with those on page 17.
16 Auxiliary Views NOTES
17 Learning Check Answers 1 1 False. Usually, completing a foreshortened view of a surface that s already shown in an auxiliary view would be a waste of drafting time. 2. True 3. True 4. False. You can darken each view as you complete it, or you may wait until all the views are finished. However, be aware that there s a greater risk of smearing the drawing when the views are darkened during construction. 1. True 2. True 2 3. False. The appropriate distance from a reference plane to the parallel surface is determined by the nature of the object and the intended size of the drawing. 4. True