1Chapter 7

Chapter 7Auxiliary Views

2Learning Objectives

L Explain the purposes of auxiliary views.L Identify auxiliary views and explain their relationship to principal

views.L Discuss terms related to auxiliary view projection.L Read prints that incorporate auxiliary views.L Discuss computer-generated auxiliary views.

Learning Objectives

3Auxiliary Views

L Created with a projection plane that is not in one of the principaldirections

L An orthographic view

Auxiliary Views

4Auxiliary View Purpose

L Can be used to show the true size and shape of an inclinedsurface

Auxiliary View Purpose

5Auxiliary View Purpose

L Used to show the true angle, or dihedral angle, of a groove

Auxiliary View Purpose

6Auxiliary Views in Education

L In education or standards, reference lines are often used to helpconstruct the auxiliary view

Auxiliary Views in Education

7Visualizing Auxiliary Views

L Turn the drawing to see the auxiliary view in a horizontal orvertical orientation

Visualizing Auxiliary Views

8Partial Auxiliary View

L Does not show the entire object

Partial Auxiliary View

9Primary Auxiliary View

L Projected from a principal viewL By dimension:T Height: projected from the top viewT Width: projected from the side viewT Depth: projected from the front view

Primary Auxiliary View

10Secondary Auxiliary View

L Projected from a primary auxiliary view

Secondary Auxiliary View

11Computer-Generated Auxiliary Views

Computer-Generated Auxiliary Views

12What do you see?

What do you see?

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15PROJECTION METHOD

PROJECTION METHOD

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PROJECTION METHOD

Perspective

ObliqueOrthographic

Axonometric Multiview

Parallel

Oblique

17PROJECTION THEORY

L The projection theory is used to graphically represent 3-D objectson 2-D media (paper, computer screen)

L The projection theory is based on two variables:T 1) Line of sightT 2) Plane of projection (image plane or picture plane)

PROJECTION THEORY

18Line of Sight

L Line of Sight is an imaginary ray of light between an observer’seye and an object

T There are 2 types of Line of SightO parallel O converge

Line of Sight

Line of sightLine of sight

Parallel projection Perspective projection

19Plane of Projection

L Plane of projection is an imaginary flat plane which the image iscreated

T The image is produced by connecting the points where the LOSpierce the projection plane.

Plane of Projection

Plane of projection

Parallel projection

Plane of projection

Perspective projection

20Disadvantage of

L Perspective projection is not used by engineers formanufacturing of parts, because

T 1) It is difficult to create.T 2) It does not reveal exact shape and size.

Disadvantage of Perspective Projection

Width is distorted

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21Orthographic projection

L Orthographic" comes from the Greek word for "straight writing (ordrawing)."

T This projection shows the object as it looks from the front, right,left, top, bottom, or back, and are typically positioned relative toeach other according to the rules of either “First Angle” or“Third Angle” projection.

Orthographic projection

22Pictorial

L 3-dimensional representationsT One-point O one vanishing point O lines that are not vertical or horizontal converge to single point in distance

T Two-point or Three-point O two or three vanishing pointsû With two points, vertical or horizontal lines parallel, but not bothû With three-point, no lines are parallel

T IsometricO Drawing shows corner of object, but parallel lines on object are parallel in

drawingO Shows three dimensions, but no vanishing point(s)

Pictorial

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One-point

Two-Point

Three-Point or Oblique Perspective

24Symbols for Third Angle or First Angle

L First angle projection is the ISO standard and is primarily used in Europe.

T The 3D object is projected into 2D "paper" space as if you werelooking at an X-ray of the object: the top view is under the front view, the right view is at the left of the front view.

L Third angle projection is primarily used in the United States and Canada, where it is the default projection system according to BS 8888:2006, the left view is placed on the left the top view on thetop.

Symbols for Third Angle or First Angle

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26Orthographic projection

L Orthographic projection is a parallel projection technique inwhich the parallel lines of sight are perpendicular to theprojection plane

Orthographic projectionMEANING

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Object views from top

Projection plane

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2

3

4

51 2 3

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Image of a part represented in First Angle Projection

28Orthographic / Multiview

L Draw object from two / three perpendicular views

Orthographic / Multiview

Orthographic

What it looks like pictorially

29Multiview Drawing

L AdvantageT It represents accurate shape and sizeL DisadvantageT Require practice in writing and readingL Example

Multiview Drawing

Multiviews drawing (2-view drawing)

30Axonometric (Isometric) Drawing

L AdvantageT Easy to understandL DisadvantageT Shape and angle distortion L Example

Axonometric (Isometric) Drawing

Circular hole becomes ellipse.

Distortions of shape and size in isometric drawing

Right angle becomes obtuse angle.

31Isometric projection

Isometric projection

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Sectional views

33Auxiliary Views

L Used to show true dimensions of an inclined plane

Auxiliary Views

Not True Size

True Size

34Auxiliary projection

Auxiliary projection

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36Isometric and Oblique Pictorials

Isometric and Oblique Pictorials

37Pictorial Drawing

L 2D illustration of a 3D objectT Shows three faces of an object in one viewT Provides a realistic view of an objectL Three typesT Isometric T ObliqueT Perspective

Pictorial Drawing

Isometric Oblique (Cavalier) PerspectiveOblique (Cabinet)

38Oblique Pictorials

L An Oblique pictorial starts with a straight-on view of one of theobject’s faces, which is often the front face

L Angled, parallel lines are drawn to one side to represent theobject’s depth.

T Common oblique angles include 30E, 45E, and 60E

Oblique Pictorials

39Oblique Pictorials

L Two common types of oblique pictorials: T Cavalier T CabinetL The difference between the two is how the depth of the object is

represented

Oblique Pictorials

Cavalier Oblique Cabinet Oblique

40Oblique Pictorials

Oblique Pictorials

Cavalier Oblique Cabinet Oblique

Object appears deeper than it actually is

More realistic view because depth does not appear distorted

41Isometric Pictorial

L Isometric means equal measure.L Three adjacent faces on a cube will share a single pointT Edges converge at one point will appear as 120 degree angles or

30 degrees from the horizon line

Isometric Pictorial

42Isometric Pictorial

L These three edges represent height, width, and depth

Isometric Pictorial

43View labels

View labels

Top, Front, Right Side view orientation

Top, Left Side, Front, view orientation

44View Selection

L Recommendations for how to select the front viewT Most natural position or useT Shows best shape and characteristic contoursT Longest dimensionsT Fewest hidden linesT Most stable and natural position

View Selection

45Orthographic View Selection

Best shapeDescription

Most natural position

No hidden edges

Longest Dimension