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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