Chair Design
8th grade project
Written by
Sony Gala
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
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)
• 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.
Center of Gravity
A structure remains standing only if its center
of gravity is directly over the perimeter of its
base.
Center of Gravity
Loads and Joints
1. What is a load?
2. What is the load on a chair?
3. What is a static load?
4. What is the static load on a chair?
5. What is a dynamic load?
6. What is the dynamic load on a chair?
7. What are joints?
8. How can one take care of weak links?
9. Why do most chairs fail?
10. What does orthotropic mean?
11. Give an example of orthotropic material.
12. How would you cut cardboard?
Orthotropic Material
1. What does orthotropic mean?
2. Give an example of orthotropic material.
3. How would you cut cardboard?
• Research
– Go to the Cardboard chairs websites from Ms.
Gala’s website.
http://www.rockdale.k12.ga.us/personal/sgala
2/8thgrade/default.aspx
• Watch video
• Read about cardboard chair designs
– Google image search on cardboard chairs
– http://www.pbs.org/wgbh/buildingbig/lab/mater
ials.html
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
(copy definition)
Orthographic Drawing – sketches made in
two dimensional views. Objects can be
seen from the front, top, side and back.
Measure your classroom chair (inches)
– Fill in the chart provided. This will give you an
idea about chair dimensions.
Standard Classroom chair
Back of chair
Chair seat
Legs or base
Length
Height
Width
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
Back of chair
Chair seat
Legs or base
Length
Height
Width
Final Design
• Use graph paper, ruler and pencil
• Orthographic drawings – front view, side
view and top view
• Show measurements
Scale 4” – 1”
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
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