Sketching For Technical Communication

Introduction to Engineering Design

Unit 4 – Sketching and Visualization

An Object: The white, enameled, steel cylindrical container has a diameter of 5 inches and a depth of 6 inches. The top of the container is open; the bottom is covered so fluids within the container will not drip out. On one side near the top of the container, there is a 5 inch long handle covered with a black, fire­proof plastic. To prevent the escape of heat, a white, enameled, round metal top (of the same material as the container) fits snugly over the top opening.

The Object:

Elements of this lesson:

Definition of Freehand sketching Advantages Examples Language of Line Types Tips on Sketching

http://www.leonet.it/comuni/vinci/

Leonardo DaVinci Sketches

Freehand Sketching Brainstorm Ideas

Communicate Ideas

Document measurements from the Field

Part of the Design Process

Freehand Sketching Form of Technical Drawing

Without the use of Instruments

Simple to highly detailed

Orthographic projections (views) or pictorials (oblique, isometric, perspectives)

Advantages Quick conceptualization

Inexpensive, few materials needed, paper and pencil

Convenient, can be done almost anywhere

Communications asset

Who sketches? Designers

– Early ideation/conceptualization – Refinement/analysis stages – more detailed and annotated

Who sketches? Drafters

– Preliminary sketches to organize thoughts

– Plan formal drawing layout

– Minimize errors in formal drawing

Who sketches? C.A.D. Operators

May sketch on graph paper to develop coordinates

Who doesn’t sketch?

Who sketches?

Sketch Quality May vary from simple and rough to highly detailed and realistic

Speed is key, but should adequately represent design intent

Quality depends upon: – Purpose – Audience – Design Intent

Idea Sketch (thumbnail) Quick, small, simple Just enough to convey concept

Detailed Sketch Emphasis on development

May include: – Dimensions – Annotations – Symbols – Shading – Shadows

Renderings (presentation)

Highly detailed and realistic May include:

– Color – Material textures – Backgrounds

Alphabet of Lines

Alphabet of Lines Construction Line: Lightly drawn lines used as guides to help all other lines and shapes be drawn properly. Usually erased after being used.

Alphabet of Lines Object Line: Thick line (.6 mm or .032 in) to show visible edges of an object

Alphabet of Lines Center Line: Lines that define the center of arcs, circles or symmetrical parts. Drawn half as thick as object lines.

Alphabet of Lines Hidden Line: Lines used to show the interior detail not visible from the outside of the part

Alphabet of Lines Short Break Line: Line that shows where a part is broken to reveal detail behind the part or to shorten a long continuous part

Alphabet of Lines Section Lines: Lines used to define where there is material after part of the object is cut away

Alphabet of Lines Leader Line: Lines used to show dimensions of arcs, circles and to show detail. Arrow head points to detail being dimensioned, line off of arrow head usually at 45 degree angle, notation at other end

Alphabet of Lines Extension Lines: Lines used to show where a dimension start and stops on an object. The line is started 1/16 in away from the part as to not be confused with object line

Alphabet of Lines Dimension Lines: Lines used to show length

Alphabet of Lines Long Break Lines: Used to show detail or to shorten very long objects that do not change in detail

Alphabet of Lines Cutting Plane Line: Line used to indicate where part has been cut away to show detail. Arrows point in the direction that cut out is viewed in

Alphabet of lines

Phantom Lines: Lines used to identify alternative positions that a part may be moved in. This example shows that the handle can only move 45 degrees from its horizontal position

Can you identify these lines?

B

A D

C

E

G F

Your Turn: A – Object Lines B – Hidden Line

C – Cutting Plane Line D – Leader Line

E – Section Lines F – Center Line

G – Dimension Lines

Some Sketching Techniques Setup

– Don’t tape down paper – Sharpen 4H pencil or select appropriate mechanical pencil for construction lines

– Construction: • Extremely light and thin • Barely seen • Easily erased (Don’t dent paper)

Isometric Projection Isometric Projection

Equal Angles (120° separation of axes)

120° 120° 120°

Isometric Projection 30° 30°

Isometric Circles & Curves Start with center lines

– Follow isometric axes of sketch plane

Isometric Circles & Curves Measure desired radius on all axes

– Small dashes following perpendicular axes

Isometric Circles & Curves Start ellipses tangent to dashes

– Don’t try sketching entire ellipse at once

Isometric Circles & Curves Finish construction by connecting curves

– Rotate paper if necessary

Isometric Circles & Curves Darken curve one quarter at a time

Isometric Circles & Curves Darken curve one quarter at a time

Orthographic View Projection

Sketch is now ready for further development – CAD drawing – 3D Model – Prototype

Steven H., Freehand Orthographic Sketch, Auburn HS, 2003

Steven H., Auburn HS, 2003

Curriculum Alignment:

Unit 4 Sketching and Visualization

Section 4.1 – Sketching Techniques

Section 4.2 – Pictorial Sketching

References: Goetsch, D.L., Chalk, W., Nelson, J.A.

(2000). Technical Drawing 4 th ed., Albany, NY: Delmar Publishers

Madeson, D.A., Folkestad, J., Schertz, K.A., Shumaker, T.M. (2002). Engineering Drawing and Design 3 rd ed., Albany, NY: Delmar Publishers

Credits: Writer: Paul Casarona

Content Editor: Donna E Scribner

Narration: Donna E. Scribner

PLTW Editor: Ed Hughes

Production: CJ Amarosa

Video Production: CJ Amarosa

Audio: CJ Amarosa

Project Manager: Donna E. Scribner

Special Thanks: Paul Casarona, John Pierce, Melinda Scribner