Sketching Multiview Drawings

1.2 Concepts

• Engineers create sketches to quickly record, communicate, and investigate ideas.

• Pictorials and tonal shading techniques are used in combination to give sketched objects a realistic look.

• Designers use isometric, oblique, perspective, and multiview sketching to maintain an object’s visual proportions.

• A multiview projection is the most common method of communicating the shape and size of an object that is intended for manufacture.

Performance Objectives

It is expected that students will:

• Identify and sketch construction lines, object lines, and hidden lines.

• Sketch an isometric view of simple geometric solids.

• Understand how an oblique view differs from an isometric view.

• Sketch one-point, two-point, and three-point perspectives of simple geometric solids.

• Sketch multiview drawings of simple geometric solids.

• Determine the front view for a given object.

Words of the Day

• Orthographic drawings – drawings where three views of an object are drawn in perpendicular planes to one another. • Isometric drawings drawings that show multiple sides of an object in one view; it forms 120 degree triangles.

• Proportion Comparative relationship of two objects regarding size.

Pictorial Drawings

• There are two types of pictorial drawings: Oblique Isometric

Isometric Drawings

• Isometric means equal measure.

• Isometric Drawings are drawn at 30 degree angles from the x axis.

• The edges that converge will appear as 120 degree angles

Oblique Drawings

• Oblique drawings show multiple views of the object but one of the axes is on a 90 degree angle and the other is on a 45 degree angle.

• An oblique starts with a straight-on view of one of the object’s faces, which is often the front view.

45 °

Orthographic Drawings

• There are typically 3 views displayed in an Orthographic drawing • Top • Front • And either the Right Side • Or the Left Side

Orthographic Views

• Notice that the Top View is positioned above the front and they are aligned • The Right Side view is positioned to the right of the front view and also aligned

Orthographic Views

• The most important view is the Front View • You must determine which will be the front • Choose the view that is the longest and the one with the most detail

Multiview Drawing

Object Descriptors All three-dimensional objects have

width

,

height

, and

depth

.

•

Width

(

side-to-side)

•

Height

(t

op-to-bottom

) •

Depth

(

front-to-back)

Object descriptors: Width Height Depth

Orthographic Projection

Orthographic projection

is a technique that is used to create multiview drawings.

The best way to understand

orthographic projection

is to imagine an object contained inside a glass box.

Orthographic Projection There is a total of six glass walls surrounding the object. Each wall represents a

projection plane

onto which a two dimensional object view will be created.

Orthographic Projection Start by focusing only on the front

projection plane

.

2 3 A person standing in front of the object would see only the five corners identified in black.

1 4 5

Orthographic Projection

Projection lines

are used to project each corner outward until they reach the

projection plane.

Orthographic Projection The

visible edges

of the object are then identified on the

projection plane

by connecting the projected corners with

object lines

.

Orthographic Projection The

orthographic projection

process is then repeated on the other

projection planes

.

Completed Multiview Drawing

Isometric (Pictorial) Orthographic

Object Line Layout

Each of the blocks at right has the same footprint. What do their top views look like?

They all have identical top views!

Proportion Good sketching should be proportional.

Good sketch Poor sketch