Unit 5 Multiview Drawings

Learning Objectives Define spatial visualization. Explain the relationship between an orthographic projection and a multiview drawing. Identify and define the three dimensions of an object. Define the six principal views and the three regular views. Identify the three principal projection planes.

Learning Objectives Explain three visualization principles for multiview drawings. Identify the three types of flat surfaces. Explain characteristics of cylindrical surfaces. Explain characteristics of fillets, rounds, and runouts. Identify differences between third-angle and first-angle projection. Discuss computer-generated views.

The Role of Spatial Skills Spatial visualization can be defined as the mental visualization of 2D and 3D shapes and objects, including such tasks as imagining objects in the mind as they are rotated, moved, or reflected in a mirror

Spatial Visualization Tools Visualization of rotations Answer: B

Spatial Visualization Tools Mental rotation with two correct rotations Answer: A and C

Spatial Visualization Tools Surface development test Answer: B

Spatial Visualization Tools Mental visualization of folding and unfolding Answer: D

Orthographic Projection Created by projecting the points of a three-dimensional object onto a two-dimensional plane

Multiview Projection Orthographic projection consisting of systematically arranged views to describe an object

Definition Summary Orthographic projection, multiview projection, and multiview drawing are interchangeable terms Represents the main type of drawing views used in industrial prints

Selection of Views Six principal views: Front Back Top Bottom Right side Left side

Selection of Views Three “regular” views commonly used in education: Front Top Right side

Selection of Views

Dimensions of an Object Height is how tall the object is, as measured on the front view Width is how wide the object is, as measured on the front view Depth is how deep the object is from front to back Each dimension appears twice in the three regular views “Length” and “breadth” are terms not used

Dimensions of an Object

Three Orientation Possibilities Perpendicular Parallel Inclined

Three Projection Possibilities Edge view True size and shape Foreshortened shape

Three Principal Planes of Projection Frontal plane Horizontal plane Profile plane

Three Types of Flat Surfaces Normal

Three Types of Flat Surfaces Inclined

Three Types of Flat Surfaces Oblique

Cylindrical and Curved Surfaces

Meanings of a Multiview Line A—Edge view of a flat or curved surface B—Intersection of two surfaces (just an edge) C—Maximum contour of a curved surface

First-Angle and Third-Angle Projection Dividing space into quadrants Historical development of projection theory used two planes to divide space After projections, the two planes are revolved into one, with quadrants two and four “collapsed”

First-Angle and Third-Angle Projection

Third-Angle Projection Used in the United States

First-Angle Projection Used in Europe

Computer-Generated Views The benefits of creating views directly from the 3D model include: Ease of construction Ease of change Accuracy in representing geometry Intelligent association between the model and the annotations

Computer-Generated Views Views created by the CAD program may need: Individual line adjustment for weight or dash spacing The representation of fillets, rounds, and runouts adjusted (see A versus B to the right) Conventional practices reviewed

What do you see? Print supplied by Sunnen Products Company.