11 Copyright Goodheart-Willcox Co., Inc. Learning Objectives After studying this unit, you will be able to: ✓ List the six principal views of an object. ✓ Understand the basic principles of orthographic projection. ✓ Identify first- and third-angle projection drawings. ✓ Visualize three-dimensional objects from orthographic drawings. ✓ Apply proper dimensioning for projected views. ✓ Draw a missing view of an object from two given views. UNIT UNIT 2 2 Key Terms first -angle projection foreshortening multiview drawing orthographic projection third-angle projection true size and shape Visualizing Shapes Visualizing Shapes The ability to read and understand prints and technical drawings is an essential skill required in the engineering and manufacturing fi elds. The key factor in print reading is the ability to visualize separate views of an object in two dimensions. Multiview Drawing Manufacturing industries use multiview drawings as a way to visualize and describe a part or assembly. Understanding a multiview drawing is an important aspect of reading prints and technical drawings. In a multiview drawing, two or more views represent the accurate shape of an object or part. A multiview drawing provides a means of visualizing a three-dimensional shape on a two-dimensional surface such as drafting paper or a computer screen. All the necessary details of a part’s shape and size are included in a multiview drawing to ensure accurate production of the part. Orthographic projection is one method used to develop multiview drawings. Orthographic projection is a way of showing the shape of an object by projecting two or more views at right angles to each other. See Figure 2-1. The terms “multiview drawings” and “orthographic projection drawings” are often used interchangeably. PRO TIP Goodheart-Willcox Publisher A simple multiview drawing is created by orthographic projection. Figure 2-1 Perpendicular projectors