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Study Unit

Auxiliary Views

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 es-sential to your complete training. Auxiliary views are used to show the true size and shape of sur-faces that aren’t parallel to any of the six principal views. A surface feature that’s not perpendicularto the line of sight is said to be foreshortened, or shorter than true length. A foreshortened view fails toclearly or accurately represent the feature.

On a drawing, an auxiliary view allows you to look directly at an inclined surface—so you can viewthe surface in its true size and shape. Normally, the information needed from the auxiliary view in-volves the inclined surface only; depicting the other areas of the object typically won’t add any clar-ity to the drawing. However, each drafting object must be considered separately. The standard forauxiliary view presentation can be found in the document Multi and Sectional View Drawings (ANSIY14.3), published by the American National Standards Institute.

Your study unit, Auxiliary Views, consists essentially of several drafting assignments. You’re to com-plete these assignments on the plates contained in the corresponding exam booklet. In effect, as youwork 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

Preview

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DRAWING AN AUXILIARY VIEW . . . . . . . . . . . . . . . . . . . . . . . 1Exam Plate E1: Auxiliary Views AExam Plate E2: Auxiliary Views B

MULTIPLE AUXILIARY VIEWS . . . . . . . . . . . . . . . . . . . . . . . . . 10Exam Plate E3: Auxiliary Views CInspecting Your Work

LEARNING CHECK ANSWERS . . . . . . . . . . . . . . . . . . . . . . . . 17

Contents

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DRAWING AN AUXILIARY VIEW

Look at the airplane’s spar clip shown as an isometric pictorial in Figure1. At first, it may seem extremely difficult to lay out this object in an or-thographic projection. However, a drafter who understands the basicprinciples of auxiliary views could complete the orthographic projectionfairly easily. With practice, creating such projections will become easyfor you as well. In fact, once you know how to make auxiliary views, youshould be able to draw just about any object, given enough informationabout the object’s shape.

Exam Plate E1: Auxiliary Views A

Your assignment for Exam Plate E1 will be to complete an auxiliary viewdepicting an object’s slanted surface. Figure 2 shows a pictorial and twocomplete 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 beenmachined through the upper part of the object. A slot was added to thishole to form a keyway. In the left-side view, the upper portion of the an-gle stop is depicted with foreshortened lines because of the slanted sur-face. The circular hole thus appears as an ellipse in the left-side view.

Auxiliary Views

1

FIGURE 1—How would youlay out this spar clip in anorthographic projection?Right now, you may beconfused about how toaccurately depict theslanted surfaces containingholes. By using primaryauxiliary views, however,you can solve this problemsimply and directly.

Actually, it would be a common practice in industry to not draw the up-per portion of the angle stop—at least not as it’s shown in the object’s left-side view. A foreshortened view of that surface isn’t necessary foraccurately describing the object. In fact, the foreshortened view would bedifficult to draw without an ellipse template, and—if drawing it doesn’tcontribute to an accurate shape description—there’s no reason for a draf-ter to spend valuable time drawing the foreshortened view. However,the inclined surface includes special features, such as the hole and key-way. Without a true view of this inclined surface, the object’s shape de-scription would be incomplete. Showing that surface in its true size andshape clearly calls for an auxiliary view.

Now, from which regular orthographic view should you project the trueview of the slanted surface? To establish an accurate auxiliary view, youmust project at right angles to the view. Thus, you’ll need to project offthe front view’s version of the inclined surface. In completing your draft-ing 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 isat the bottom.

• Referring to Figure 2, lay out the left-side view and front view ofthe angle stop.

• Use light pressure for this preliminary layout.

FIGURE 2—Your assignment is to complete a primary auxiliary view of the angle stop’s slanted portion. The left-sideand front views of the angle stop are shown here next to the pictorial.

2 Auxiliary Views

Step 2: Add the reference planes.

• Make one reference plane (which is sometimes also called a refer-ence 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 centerof the holes shown in the left-side view.

• Label both reference planes RP. Your drawing should now looksomething like what’s shown in Figure 3. The only difference isthat the upper portion of the angle stop will be broken off and notshown in your drawing. (Your auxiliary view will show this por-tion 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 surfaceup through and slightly beyond the reference plane.

• Later, you’ll mark off these projection lines with dimensionalpoints.

Step 4: Refer to the left-side view to get the depth dimensions for the auxiliaryview.

• By looking at the left-side view, you can determine the depth di-mensions for the drawing. (In fact, any primary orthographic viewthat’s projected from a front view can be used to determine the truedepth of the object.)

• Using your dividers, transfer the depth dimensions from the left-side 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

FIGURE 3—Here is shown thelayout of the left-side view,the front view, and thereference planes (RP).

Auxiliary Views 3

included in Figure 4 to show you exactly how each depth dimen-sion is transferred. On your drawing, though, you should have nolabeled dimensions. In addition, the upper portion of the angle stopwon’t appear in your drawing as it’s shown in Figure 4. Your auxil-iary view will show that part of the object.

Step 5: Complete the auxiliary view.

• To complete the light-line construction of the auxiliary view, joinall the points together. Add the correctly curved edges and the key-way. Specifications for these features are given on the pictorial inFigure 2.

• Note in Figure 5 that the upper part of the object appears to havebeen “broken away” from the left-side view. This part of the objectis effectively represented in the auxiliary view. Completing a sec-ond view of this slanted surface would serve no useful purposehere; 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 youconform to the standards for drawing visible lines. The hiddenlines, centerlines, and reference plane lines should be darkenedwith your 4H lead.

• Make the title of Exam Plate E1 “Auxiliary Views A.”

FIGURE 4—The auxiliary viewcan be projected up fromthe slanted surface in thefront view as shown here.

4 Auxiliary Views

Exam Plate E2: Auxiliary Views B

For your next drafting assignment, you’ll practice laying out and draw-ing an auxiliary view of an inclined surface without the aid of a pictorial.Now, you’ll use only the information given in the two orthographicviews. Usually, these are similar to the conditions under which you’ll beworking on an actual job. Often, you’ll have only a minimum of informa-tion from which to start your drawing. As a result, you must continuallydevelop your powers of visualization. Always study every detail of yourinstructions and reading assignments.

By now you may be impressed with the amount of knowledge you needto be a successful drafter. This knowledge, though, can be learned read-ily because each of your lessons—each new thing that you learn—buildson what you’ve learned previously. The more you learn, the more youbecome capable of learning.

Taking a Closer Look

As already mentioned, your assignment here is to complete an auxiliaryview based on two existing orthographic views. Figure 6 shows tworegular orthographic views—a front view and a top view—of an objectcalled 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’scurrently a part of the top view.

FIGURE 5—Once the auxil-iary view is added to thepartial left-side view and thetop view, the shape descrip-tion of the object is com-plete.

Auxiliary Views 5

Completing the View

Step 1: Set up Exam Plate E2.

• Tape Exam Plate E2 to your drafting board so that the title block isat 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 21⁄4′′ dimensions to ori-ent 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 yourdrawing is complete and then darken all the views at once. Somedrafters like to darken the views after the layout is complete.(Smearing may sometimes result if the views are darkened duringconstruction.)

FIGURE 6—Your job here is to draw the anchor lug,including a completeauxiliary view of the slantedsurface. On your drawing,therefore, you won’t need toshow the hole and theobject’s rounded end aspart of the top view.

6 Auxiliary Views

FIGURE 7—Here is a four-part sequence showing how your drawing should develop.

Auxiliary Views 7

Step 3: Lay out the top view.

• Refer to block 2 of Figure 7. Note that the top view is positioned sothat its bottom edge is 21⁄2′′ from the upper left corner of the frontview.

• 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 partof the top view, you would need to draw elliptical curves. As men-tioned previously, drawing such foreshortened views is time con-suming and often serves no useful purpose. Therefore, simplysketch a break line across the top view to indicate where theslanted part of the anchor lug had been “broken away.”

Step 4: Add the reference planes.

• Add the reference plane for the auxiliary view 21⁄2′′ away from thefront view. As shown in Figure 7, block 2, this reference plane isparallel to the angular surface in the front view.

• Add the auxiliary reference plane through the center of the topview 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 linesfrom the top view into the broken-away area as indicated.

• With your dividers, transfer the dimensions d1 and d2 from the topview to the auxiliary view. Use these transferred dimensions todraw 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. Drawthe full radius arc with your compass. Note that this arc takes upthe full depth of the view. Draw the 1′′ diameter circle with yourcircle template.

Step 7: Finish the drawing.

• Darken in the views as required.

• When you’re finished with the drawing, your completed problemshould look similar to what’s shown in Figure 8. You don’t need toerase your construction lines if they’re very light. Constructionlines 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 6Hlead.

• The title of Exam Plate E2 is “Auxiliary Views B.”

8 Auxiliary Views

Now, take a few moments to review what you’ve learned about drawingan auxiliary view by completing Learning Check 1.

FIGURE 8—This is how yourcompleted drawing shouldappear on Exam Plate E2.On your exam plate though,the drawing will be orientedso that the auxiliary view is in the top left corner of the plate.

Learning Check 1At the end of each section of Auxiliary Views, you’ll be asked to checkyour understanding of what you’ve just read by completing a “LearningCheck.” Writing the answers to these questions will help you reviewwhat 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 bottomview 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 auxiliaryviews—must be darkened at the same time.

Check your answers with those on page 17.

Auxiliary Views 9

MULTIPLE AUXILIARY VIEWS

Exam Plate E3: Auxiliary Views CSometimes, it may not be possible to reveal the true size and shape of an ob-ject using only one auxiliary view. Look, for example, at surface 1-2-3-4 inFigure 9. In each of the six principal orthographic views, this inclined sur-face would be foreshortened. Normally, a single auxiliary view set in aplane parallel to the inclined surface is all you would need to describe theshape of that surface accurately. However, in this situation, all the edges ofthe inclined surface are also foreshortened in the principal orthographicviews. To project an auxiliary view of an inclined surface, you need to startfrom at least one edge drawn to the proper (true) length. In Figure 9, a pri-mary 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 hadbeen established, dimensional points were projected onto a secondary auxil-iary 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.

10 Auxiliary Views

However, a second auxiliary view on a drawing isn’t necessarily a secon-dary 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 areneeded to complete the object’s shape description. Both of these viewswill be primary auxiliary views. Some complicated objects require adozen or more primary views (or portions of views) to create a completeshape description.

Figure 10 shows a pictorial view of the shaft bracket you’ll be drawing onExam Plate E3. Separate auxiliary views will be necessary to describe thetwo inclined surfaces that are part of this object. If you can visualize theprincipal orthographic views of this bracket, however, you can see thatthe required edge views of the two surfaces already exist in the regularorthographic projection. Thus, you won’t need to create primary and sec-ondary auxiliary views to draw this object. Remember, a primary auxil-iary view is projected directly from one of the six principal orthographicviews; a secondary auxiliary view is projected from a primary auxiliaryview.

Taking a Closer Look

Now, let’s take a closer look at the shaft bracket shown in Figure 9. Thebracket consists of three distinct geometric shapes:

• A round, straight piece 21⁄4′′ long and with a 21⁄4′′ diameter

• A lug shaped like a two-pronged fork and set in an inclined surfaceangled up 30°

• A lug with a full radius on its end and also set in an inclined sur-face, but angled down 30°

FIGURE 10—To produce anaccurate shape descriptionof the shaft bracket shownhere, you’ll need to createtwo auxiliary views. Bothviews, however, will beprimary auxiliary views.

Auxiliary Views 11

If you were to lay out the top view and front view of the object, yourdrawing would look similar to what’s shown in Figure 11. Note that thelugs are broken away in the top view. The two lugs would be fore-shortened in that view, and drawing them in that way would contributelittle to an accurate shape description. In the front view, the inclined sur-face on each side begins 13⁄8′′ from the centerline of the 21⁄4′′D piece inthe middle. Do you see how a complete shape description of this objectwill require two primary auxiliary views? Each lug requires a separateauxiliary 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 isat 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 referenceplane) 11⁄2′′ from the top border.

• Place the lower edge of the front view 11⁄4′′ 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 informationonly. Don’t include them on your drawing. The distance to the ref-erence planes are indicated in Figure 12.

FIGURE 11—Shown here isthe layout of the top andfront views of the shaftbracket. The foreshortenedviews of the two lugs havebeen broken away from thetop view.

12 Auxiliary Views

• The reference planes are drawn parallel to the inclined surfaces.The distance to a parallel reference plane is determined by the na-ture of the object and the size of the drawing. In this case, a 13⁄8′′space above the left-hand lug and a 13⁄8′′ space below the right-hand lug provide sufficient room for the auxiliary views.

Step 3: Lay out the left and right auxiliary views.

• Show only the true size and shape of the inclined surfaces. Providebreak lines for each auxiliary view in a way similar to how it wasdone in the top view.

• When you’re done laying out the auxiliary views, your drawingshould look similar to what’s shown in Figure 13.

Step 4: Finish the drawing.

• When you’re finished with your light-line construction, darken theviews. Use a 2H lead in the compass for your compass lines.

• Follow all the standards for creating drafting lines. Never let up onquality. Quality lines and lettering may be your ticket to a good jobin the future.

• The title of Exam Plate E3 is “Auxiliary Views C.”

FIGURE 12—Once the reference planes are added, your drawing should appear as shown here.

Auxiliary Views 13

Inspecting Your Work

After you’ve finished your exam plates, inspect your work by consider-ing the following points.

• Do you have any dimensions that don’t belong on the finisheddrawings? If you do, make the necessary corrections.

• Are all your lines correctly drawn? Fix any lines that don’t conformto the standards.

• Did you apply enough pressure for color to penetrate into the fi-bers of the paper? Even a black line may be dark only on the sur-face of the drawing paper. If the drawing was to get reproduced,this surface layer of graphite can wear away, leaving behind aweak line.

• Check the overall appearance of your work. Are your drawingsfree from smudging?

Now, take a few moments to review what you’ve learned about drawingmultiple auxiliary views by completing Learning Check 2.

FIGURE 13—Your light-line construction, including both of the primary auxiliary views, should appear as shown here.

14 Auxiliary Views

Learning Check 2Indicate 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 sixprincipal orthographic views.

_____ 3. To ensure that your drawing has an overall neat appearance, you should always spacereference 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.

Auxiliary Views 15

NOTES

16 Auxiliary Views

1

1 False. Usually, completing a foreshortenedview of a surface that’s already shown inan auxiliary view would be a waste ofdrafting time.

2. True

3. True

4. False. You can darken each view as youcomplete it, or you may wait until all theviews are finished. However, be awarethat there’s a greater risk of smearing thedrawing when the views are darkenedduring construction.

2

1. True

2. True

3. False. The appropriate distance from a reference plane to the parallel surface isdetermined by the nature of the objectand the intended size of the drawing.

4. True

Learning Check Answers

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