Sketching
Prof. Jon Southen
October 8, 2008
Sketches from Leonardo da Vinci’s
Design Notebook
Thomas Edison's Sketches
A sketch showing the basic
circuit for energizing a
discharge tube.
First sketch of the phonograph, 1877
Sketching in Engineering

Text Reference:
 Bertoline-Wiebe, Fundamentals of Graphics
Communication, Fifth Edition
 This lecture: Chapter 2
Sketching in Engineering

Objectives
 Demonstrate
the Importance of Sketching.
Sketching in Engineering

Objectives
 Demonstrate
the Importance of Sketching.
 Introduce Sketching Techniques

Drawing simple lines and curves, using construction
lines, bounding lines, etc.
The Importance of Sketching




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Sketching quickly communicates design
ideas.
It’s a necessary skill for any technical
person.
Often part of the creative process –
Generation of Design Concepts.
Helps to visualize 3D objects from 2D
images.
Used extensively in Engineering.
The Importance of Sketching
Not Just for Design - Engineering Inspections
The Importance of Sketching

In your field
book......to
describe what you
saw (e.g.
damage/defects)
The Importance of Sketching





Sketching quickly communicates design
ideas.
It’s a necessary skill for any technical
person.
Often part of the creative process –
Generation of Design Concepts.
Helps to visualize 3D objects from 2D
images.
Used extensively in Engineering.
The Role of Sketching

Talking sketches
 Informal

Thinking sketches
 To

communication
help you think creatively
Prescriptive sketches
 Document
design ideas
Example in Design
Problem Definition:
Sketch shows crosssection of a Hong
Kong skyscraper
tested in the wind
tunnel.
Tuned mass damper
required to prevent
excessive vibrations.
Example in Design
Preliminary Idea
Generation:
After considering other
alternatives, a
pendulum damper was
selected as the best
option.
The design progressed
with this basic shape.
Example in Design
Constraints:
After some detailed
engineering calculations,
the final requirements
were determined and
details could be worked
out with sketches.
The final unit has to meet
all of the constraints.
Example in Design
Example in Design
Final detailed
CAD model of
the prototype
Basis of
tender
documents
Working Drawings
Working Drawings – cont’d
The Importance of Sketching
Plan good
for Layout
and Cost.
 But how
will it look?

The Importance of Sketching
Evaluate Options/Different Concepts
 Helps to visualize in 3-D.

The Importance of Sketching

To help
sort out
the
details.
What do you need…

Sketching tools - pencils, paper and a
big eraser.

patience and practice – with these you
can be good at making quick, clear, wellproportioned sketches regardless of
your experience or natural ability
Sketching Practice
Techniques

Contour Sketching

Negative-space Sketching

Upside-down Sketching
Contour Sketching
Contour Sketching
NegativeSpace
Sketching
Fundamental Techniques

Straight Lines

Curved Lines

Construction Lines and Proportions

Lettering
Straight Lines
Mechanical
MARK END-POINTS
Sketched
MARK END-POINTS
Good
No!
No!
No!
Straight Lines

Begin using grid paper, or the clear side
of graph paper.

Mark the endpoints of the line to be
drawn

Lines should be straight, continuous and
dark with uniform thickness
Straight Lines
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Long lines are difficult. Use grid paper as
a guide or reduce the size of the sketch.
Do not fix paper to the table, and rotate it
to find an easier angle for drawing lines.
Draw away from yourself or at a slight
angle.
Relax your hand (Go for it!).
Line Types
Line Precedence

Visible lines have top priority

Hidden lines do not cross or have priority
over visible lines

Centre lines do not cross or have priority
over visible or hidden lines
Curved Lines

Curved lines are essentially
interpolations between 2 or more points.
These points are typically marked as
intersecting lines or tangents

Circles and ellipses require construction
lines.

Control the degree of curvature - not too
flat, not too curved
Construction Lines

The first step is drawing construction lines
that form the backbone the sketch.

These very light thin lines roughly layout
some of the details

Do not erase them!
Curved Lines
Circles and Ellipses
Circles and Ellipses
Use diagonals to proportion
Creating a
Proportioned
Sketch
Lettering
Creativity Vignette
Design Sketch of a Concept
Due week of October 27
Requirements:
Each individual should prepare freehand sketches of one design alternative, using proper sketching
practices. Do not use a straightedge to draw your sketch. Your sketches should clearly communicate the
design concept and must include sufficient views, sections and details. Use text annotations to describe and
explain parts of the sketch. Ask your team mates for feedback. Are they able to understand what you have
drawn? Better even, ask other teams to evaluate your sketches or have a TA look at them.
Evaluation Criteria:
The evaluation criteria specify criteria and assessment descriptors in the following four broad categories.
Points will be awarded in each category as shown below.
Assessment category
Sketch Quality:
 Sketch fits the page well
 Lines are clear and well drawn
 Appropriate line thicknesses used
 Appropriate use of annotation
Multi-views:
 Views properly placed and aligned
and necessary sections and details
provided
 Each view is correctly drawn and

Maximum points
1.0
1.0
1.0
1.0
1.5
1.5
1.0
important lines shown
Proper use of hidden lines, center
lines etc.
Dimensioning:
 Dimensions drawn correctly
 Circules and curves dimensioned
Properly
Total
1.0
1.0
10
Sketching in Engineering

Review
 Look
over practice problems from textbook to improve
your sketching technique

Next Class
 Types
of Engineering Drawings
 Projections
 Views