Communicating Designs Graphically.

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EST 200, Communicating Designs Graphically

• MEC

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Contents

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

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

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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.

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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.

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Design Drawings

• 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.

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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.

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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.

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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.

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Design Drawing Example
Marginalia
Sketch
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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.

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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.

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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.

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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.

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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.

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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 papers grid.
• No need to use a ruler.
• Good idea to think ahead of the components to be
  sketched before drawing actually begins.

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Proportion Control

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

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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.

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

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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.

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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.

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Writing Fabrication Specifications

• Prescriptive fabrication specification - specify
  a particular part and its number in a vendors
  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.

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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.

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Layout Drawings
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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.

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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.
• Designers initials and date drawn.
• Dimensions and units.
• Permissible variations/tolerances.

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Detail Drawings
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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.

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Assembly Drawings
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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.

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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.

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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.

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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.

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Learn to use them.
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Thank You