Exercise: Clay Linkage

The four-bar linkage is a fundamental mechanism used to transmit and transform motion. Examples include crankshafts which convert between reciprocating and rotating motion; reciprocating linkages to amplify or reduce a reciprocating motion, e.g. the servo tie rods; concealed hinges; straight-line mechanisms; and much more.

The purpose of this exercise is twofold: gaining experience working with air-drying clay, and choosing a linkage design.


After this exercise, you should be able to:

  1. Construct a mechanism from air-drying clay.

  2. Choose four-bar linkage dimensions to create a specific movement.

Steps and observations

The overall objective is to create a four-linkage as a test: four rigid parts coupled by four pivot joints with parallel axes.

Materials: air-drying clay and paper clips.

  1. Please first duplicate and experiment with the “four-bar linkage demo” Fusion 360 design in the “examples - mechanical structures” folder of the “CKS Course Resources” project of the “Dr. Zeglin” team space.

  2. The Change Parameters dialog will identify the four link lengths as parameters; please explore to find a set of link ratios which create a particular movement.

  3. Using the air-drying clay, fashion the four links to match the ratios. Be sure to poke small pivot holes through. Relatively flat links are acceptable, although considering the stacking dimension will make for a better final fit. You may consider using wax paper or foil to separate parts and form them in place for a more perfect fit.

  4. Allow the links to dry overnight.

  5. Use bent paper clips to form pivots and assemble the linkage.


Note: please your name as a prefix on the filename for all files uploaded to Canvas. This will help me greatly keeping them sorted out during my review. E.g., I might name my own files as “Garth-project.mp4” or “Zeglin-tactile.ino”.

The result of your explorations should include the following Canvas file submissions:

  1. a brief video (~30 seconds) demonstrating operation of your device

  2. one or more high-resolution photos