Chapter 5

Sketching Applications

Introduction• Sketching (i.e., freehand drawing)

– Drawing without drafting equipment– Only paper, pencil, and an eraser needed– Fast, visual communication– Asset for communicating technical concepts

Introduction• Sketching may be used by:

– Drafters– Computer-aided drafters– Architects– Designers

Sketching Tools and Materials• Pencils

– Should have soft lead• Common No. 2• Mechanical pencil with H, F, or HB lead• Automatic 0.7-mm or 0.9-mm pencil with F or HB lead

– Point should be slightly rounded

• Paper– Almost any type works

Sketching Straight Lines

Sketching Circular Lines• Techniques:

– Trammel method– Hand-compass method– Nail-and-string method

Measurement Lines and Proportions

• All lines are related in sketches– Size and direction

• Sketches should be proportional– Actual size depends on paper and sketch size

• Pencils – May used as a ruler for measurement

Measurement Lines and Proportions (cont’d.)

• Blocking – Helps determine shapes and proportions

Introduction to Multiview Sketches• Multiview projection

– Views of an object as projected upon two or more picture planes in orthographic projection

• Elevation views– Two-dimensional views established by a line of

sight perpendicular to the object surface

Isometric Sketches• Provide a three-dimensional (3D) pictorial

representation of an object– Isometric lines are on or parallel to one of the

three original isometric axes– Circles and arcs appear as ellipses

Orthographic Projection• Projection of features of an object onto an

imaginary plane (i.e., plane of projection)– Projection of features is made by lines of sight

perpendicular to the plane of projection

Multiview Projection• Establishes two or more views of an object

as projected on two or more planes – Uses orthographic projection techniques

• Elevations– Two-dimensional exterior views of a structure

• Proper view selection– Six primary views

Projection of Features from an Inclined Plane

• In multiview projection, features of objects that are: – Parallel to projection planes appear true size

and shape– Not parallel to projection planes are

foreshortened, and not in true size and shape