Chair Design

1. Chair Design 8th grade project Written by Sony Gala

2. 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

3. 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)

4. 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.

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

7. 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?

8. Orthotropic Material • What does orthotropic mean? • Give an example of orthotropic material. • How would you cut cardboard?

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

10. 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

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

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

13. 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.

14. Final Design • Use graph paper, ruler and pencil • Orthographic drawings – front view, side view and top view • Show measurements Scale 4” – 1” 18 inches

15. 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

16. 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