Jansen Mechanism

The Theo Jansen mechanism is a kinetic sculpture that can move with the help of several pairs of legs.

I have used 15 straws, two wood sticks, a coper wire and adhesive tape.

Theo Jensen has calculated the right dimensions for this mechanism using computer simulations. So we will borrow these dimensions from him.
Note that two opposite legs, or a pair, will have a common "a" arm, double in lenght.

First of all cut the straws according to the dimensions from previous step. Use whatever measurement unit fits to your material. I have used millimeters.
Make the "j" and "k" arms ten units longer and the "a" arm double in size.
For easier work, flatten the tubes.
Using adhesive tape, bind the pieces together. A pair of legs is formed by two modules, in a mirrored position, linked via the "a" arm.
You need at least 3 pairs of legs.

Using a safety pin bind together the "j" and "k" arms of each pair of legs.
Note that the two ends of each "j" and "k" arms are flatten in perpendicular planes.

In this step i have noticed that the "a" arms are hindering the movement of the legs. To resolve this, I have moved them away from the legs, and I have used two wood sticks to consolidate the structure. Note that all the "a" arms and wooden stick are in the same plane. They form the rigid structure of the mechanism.

Remove the safety pins and replace them with a coper wire.
Bend the wire in the shape of a crankshaft. The outside pair of legs must be in the same phase while the middle pair must be in the opposite phase.

This is how you can do it.
It should