Chebyshev Linkage

This linkage translates rotational movement to approximately straight-line movement.

Steps

1. Cut out the pieces from card stock using the pattern. You can use an old manila folder if you don't have card stock. The short dotted lines at the top and bottom of the page can help you line up cuts on a paper cutter.
   
2. Punch holes where marked. You may have to cut out a hole with a craft knife wherever your hole-punch doesn't reach.
   
3. Cut along the lines of the tabs using a craft knife.
   
4. Connect the two longest pieces to the rectangle at the points A and B on the rectangle. To do this, lift up the two tabs perpendicular to the piece and curl the ends in so that the pieces with the holes can slip over them. Flatten the tabs again, thus holding the pieces in place.
   
5. Lift up the tabs point C on the small crossbar. Push the tabs down at point D. Connect it to the longest pieces. Note that the tabs at D will go down to the underside of the model.
   
6. Hold the rectangular piece flat onto the table (or tape it down) and swing the long arms. Notice that the hole in the short bar travels in a nearly straight line.