1. Lab 6 Kinematics & Constraints

2. Make 2 and 3-D models Work as individuals but refer to lab partners Read Doug Blanding’s booklet for ideas Start with 2-D models out of manila folders Punch works well for making holes for joints Stick pins for grounded joints Thumbtacks for free joints

3. Suggested models – single constraint One grounded joint – only rotation One swivel joint – rotation and translation

4. Dual in-line constraints Ground joints 1 & 4 and make 2 & 3 a little long What happens? Toggle or oil can effect

5. Dual constraints – not parallel – virtual pivot

6. Dual constraints - parallel Instantaneous center of rotation is at infinity But translational modes constrained Add second set of parallel constraints

7. Cascading constraints Practical application – Drafting machine – parallel motion in 2-D

8. Exact 2-D constraints Design a “tangent bar” constraint for a circular disk This is often used for the radial constraint of a telescope mirror

9. Practical examples of 2-D exact constraints

10. 2-D exact constraint table

11. 3-D exact constraint table

12. Build 3-D constraint systems Use swab sticks, capplugs and hot glue gun to make models Careful with the glue gun – the glue can burn if it is still hot

13. Make some compound connections Use manila folder sheet material and glue gun

14. Investigate stiffening sheets

15. 2-D Trusses

16. Rigid 3-D structures