Chair Design

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Chair Design

• 8th grade project

Written by Sony Gala
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Problem

• Students will use the engineering design process
  to design and build a cardboard chair. The
  teacher will sit in the chair for at least 90
  seconds.
• Final products
• Engineering design portfolio (need not be typed)
• ¼ scale chair
• Cardboard chair

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Requirements

• Students will work in groups of four
• Assign each member a duty
• Member Name - Design Engineer
• Member Name - Document handler
• Member Name - Researcher
• Member Name - Material handler
• Decide on a group name relate to the project
  (ex CardChairs R Us)

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• Requirements
• 2 sheets of cardboard 7 x 3.5
• Chair must have a back
• Seat of chair must be at least 18 off the floor.
• Constraints
• Students will not use any form of adhesives to
  build the cardboard chair
• No glue, tape, staples, nails etc.

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(No Transcript)
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Center of Gravity

• A structure remains standing only if its center
  of gravity is directly over the perimeter of its
  base.

Center of Gravity
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Loads and Joints

• 1. What is a load?
• What is the load on a chair?
• What is a static load?
• What is the static load on a chair?
• What is a dynamic load?
• What is the dynamic load on a chair?
• What are joints?
• How can one take care of weak links?
• Why do most chairs fail?
• 10. What does orthotropic mean?
• 11. Give an example of orthotropic material.
• 12. How would you cut cardboard?

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Orthotropic Material

1. What does orthotropic mean?
2. Give an example of orthotropic material.
3. How would you cut cardboard?

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• Research
• Go to the Cardboard chairs websites from Ms.
  Galas website.
• http//www.rockdale.k12.ga.us/personal/sgala2/8th
  grade/default.aspx
• Watch video
• Read about cardboard chair designs
• Google image search on cardboard chairs
• http//www.pbs.org/wgbh/buildingbig/lab/materials.
  html

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Alternative Solutions

• Each student in a group sketches three chairs you
  may have at home or school.
• ex dining chair, sofa chair, office chair, deck
  chair, lawn chair, etc.
• Think about form, comfort, looks etc.
• Sketch ideas for cardboard chair.
• Use graph paper

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• (copy definition)
• Orthographic Drawing sketches made in two
  dimensional views. Objects can be seen from the
  front, top, side and back.

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• Measure your classroom chair (inches)
• Fill in the chart provided. This will give you an
  idea about chair dimensions.

Standard Classroom chair Length Height Width
Back of chair
Chair seat
Legs or base
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Plan on measurements for cardboard chair
(inches) Fill in chart. Convert all measurements
to ¼ scale. Divide each number by 4. Write ¼
scale number in parenthesis.
Your Cardboard Chair Length Height Width
Back of chair
Chair seat
Legs or base
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Final Design

• Use graph paper, ruler and pencil
• Orthographic drawings front view, side view and
  top view
• Show measurements

Scale 4 1
18 inches
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¼ scale chairs

• Refer to the orthographic drawing
• Use one sheet of poster paper
• Draw and cut out patterns to build a ¼ scale
  chair.
• Remember no adhesives or attachements of any type

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Full Size Chairs

• First draw patterns on the cardboard sheets
• Minimize use of material
• Use gloves, base cardboard mats and box cutters
• Score cardboard to make sharp folds
• Cut slots that are straight and parallel to make
  tight joints