This document discusses various methods for engineers to communicate designs graphically, including sketches, drawings, and other representations. It covers sketching techniques like orthographic, axonometric, oblique, and perspective sketches. It also discusses design drawings, including layout drawings, detail drawings, and assembly drawings. Fabrication specifications and standards are important to unambiguously communicate a design to manufacturing. Overall, graphical communication is a critical skill for engineers to effectively convey their designs to others.

1. 1
EST 200, Communicating
Designs Graphically
MEC

2. 2
Contents
• Engineering Communication.
• Graphical Communication.
• Sketching.
• Engineering Drawings.
• Fabrication Specifications.
• Design Drawings.
• Other Pictorial Representations.

3. 3
“The eyes believe themselves; the ears believe
other people.”
- A German Proverb.
“One showing is worth a hundred sayings.”
- A Chinese Proverb.

4. 4
How Engineers Communicate
• Being able to communicate effectively a
critical skill for engineers.
• Communicate individually and as
members of design teams.
• Communicate through oral presentations,
through written documents, and technical
drawings.
• Communication more effective through
models or prototypes to demonstrate or
evaluate design effectiveness.

5. 5
Design Drawings
• Information created and transmitted in the
drawing process.
• Design drawings include sketches,
freehand drawings, and computer-aided
design and drafting (CADD) models.
• Simple wire-frame drawings (such as stick
figures) to solid models (3D figures).
• Drawing, the process of putting “marks on
paper.”

6. 6
• Marks include sketches and marginalia.
• Sketches of objects and their associated
functions.
• Marginalia include notes in text form, lists,
dimensions, and calculations written on
margins.
• Drawings enable a parallel display of
information.
Design Drawings

7. 7
Design Drawings
• Drawings surrounded with adjacent notes,
smaller pictures, formulas, and other
pointers to ideas related to the object
being drawn and designed.
• Notes next to a sketch, a powerful way to
organize information.
• Graphic images to communicate with other
designers, client, and manufacturing
organization.

8. 8
Sketches and Drawings
• Serve as a launching pad for a brand-new
design.
• Support the analysis of a design as it
evolves.
• Simulate the behavior or performance of a
design.
• Record the shape or geometry of a design.

9. 9
Sketches and Drawings
• Communicate design ideas among
designers.
• Ensure that a design is complete.
• Drawing and its associated marginalia
remind of still-undone parts of that design.
• Communicate the final design to the
manufacturing specialists.

10. 10
Design Drawing Example
Sketch
Marginalia

11. 11
Sketching
• A powerful tool in design.
• Permits designer to convey design ideas
quickly and concisely.
• Puts design thoughts on paper.
• Starting point for other design activities.
• Types of sketches:
- orthographic sketches.
- axonometric sketches.
- oblique sketches.
- perspective sketches.

12. 12
Orthographic Sketches
• Projection of a single
view of an object
(such as a view of the
front) onto a drawing
surface.
• 3D object in 2D.
• Lay out of the front,
right and top views of
a part.

13. 13
Axonometric Sketches
• Starts with an axis (corner
of the part), typically a
vertical line with two lines
30o from the horizontal.
• Object then blocked in using
light lines, with the overall
size first.
• Vertical lines darkened,
followed by other lines.
• All lines in the sketch either
vertical or parallel to one of
the two 30o lines.
• Part details added last.

14. 14
Oblique Sketches
• Most common type of
quick sketch.
• Front view blocked in
roughly first,
• Depth lines then
added.
• Details such as
rounded edges added
last.

15. 15
Perspective Sketches
• Similar to oblique sketches.
• Front view blocked in first.
• A vanishing point chosen,
projection lines drawn from
the points on the object to
the vanishing point.
• Depth of the part then
blocked in using the
projection lines.
• Details added finally to the
part.

16. 16
Proportion Control
• To show the relative sizes of parts,
components, or features in a sketch.
• Sketch designs on graph paper, because it
is easier to control the relative sizes using
the graph paper’s grid.
• No need to use a ruler.
• Good idea to think ahead of the
components to be sketched before
drawing actually begins.

17. 17
Proportion Control
• First “block in” the overall length and width
of a part.
• Lay out the largest component first.
• Then add details.

18. 18
Annotation
• Annotations to be clear and easy to read.
• Clear, easily read notes on sketches
convey the meaning behind the sketched
ideas.
• Evenly spaced block letters are generally
much clearer than cursive scribbles.

19. 19
Well annotated using
block lettering.
Clear, drawn proportionately.

20. 20
Fabrication Specifications
• Need to communicate with the maker or
manufacturer of the designed artifact.
• Representations or descriptions of the
designed object are included in the final
design drawings.
• To be complete, unambiguous, clear, and
readily understood.
• Design drawings prepared in accordance
with relevant engineering practices and
standards.

21. 21
Why Fabrication Specifications?
• Design must perform as the designer
intended.
• Designer unlikely to be involved in the
actual manufacture of the design result.
• Designers may not be around to catch
errors or to make suggestions.
• Maker may be a different person.
• Maker cannot turn around to seek
clarification or ask on-the-spot questions.

22. 22
Properties of Fabrication
Specifications
• Device/product to be built by someone
totally unconnected to the designer/design
process.
• Unambiguous - role and place of each and
every component and part must be
unmistakable.
• Complete - comprehensive and entire in
their scope.
• Transparent – readily understood by the
manufacturer or fabricator.

23. 23
Writing Fabrication Specifications
• Prescriptive fabrication specification -
specify a particular part and its number in
a vendor’s catalog.
• Procedural fabrication specification -
specify a class of devices that do certain
things.
• Performance fabrication specification -
leave it up to a supplier or the fabricator to
insert something that achieves a certain
function to a specified level.

24. 24
Design Drawings
• Layout drawings:
- to show the major parts or components
of a device and their relationship.
- drawn to scale, do not show tolerances.
- subject to change as the design process
evolves.

25. 25
Layout Drawings

26. 26
Design Drawings
• Detail Drawings:
- show individual parts or components
of a device and their relationship.
- show tolerances, specify materials and
any special processing requirements.
- drawn in conformance with existing
standards.
- changed only when a formal change
order provides authorization.

27. 27
Essential Components
• Standard drawing views.
• Standard symbols to indicate particular
items.
• Clear lettering and clear steady lines.
• Appropriate notes and material
specifications.
• Title on the drawing.
• Designer’s initials and date drawn.
• Dimensions and units.
• Permissible variations/tolerances.

28. 28
Detail Drawings

29. 29
Design Drawings
• Assembly Drawings:
- show how individual parts/ components
of a device fit together.
- exploded view to show “fit” relationships.
- bill of materials to identify components
by part numbers or entries.
- bill of materials include detail drawings if
major views in detail drawings cannot
show all required information.

30. 30
Assembly Drawings

31. 31
Tolerances
• Impossible to make two objects exactly the
same.
• May appear to be the same due to our
limited ability to distinguish differences at
extremely small or fine resolution.
• Tolerances to define permissible ranges of
variation in critical or sensitive dimensions.
• Tolerances prescribe limits.

32. 32
Standards
• Articulate the best current engineering
practices in routine or common design
situations.
• Indicate performance bars that must be
met for drawings.
• Individual standards written by
professional societies and associations.

33. 33
Other Pictorial Representations
• To extend limited human abilities to flesh
out and communicate complicated
pictures.
• Circuit diagrams to represent electronic
devices.
• Flowcharts to represent chemical-
engineering process plant designs.
• Block diagrams to represent control
systems.

34. 34
Comments
“There are habits and styles of thought that
are common to the design enterprise,
there are also practices and standards that
are unique to each discipline. It is the
responsibility of the designer to learn and
use them wisely.”

35. 35
Learn to use
them.

36. 36
Thank You