A whirligig is any toy or contraption with at least one part that spins or whirls. Whirligigs have been used throughout recorded history as weather vanes, windmills and toys. According to the book "The Woodworker's guide to Pricing your Work," George Washington brought "whirlagigs" home to Mount Vernon after the Revolutionary War. Today a whirligig may be used in children's toys, folk art or even in production of electricity thanks to wind-powered turbines. Here is the look at the anatomy of a Whirligig.
Many whirligigs are wind-powered cranks. These cranks are moved by catching wind through the tilting arms of a propeller. As the wind blows over the tilting arm, it pushes against the resistance of the propeller arm. The propeller arm is pushed on a central hub, which turns the whole propeller. Some whirligigs have two or more propellers, spinners or trip levers to create multiple effects.
A cam is a specially shaped piece of metal or plastic that is attached to the hub onto which the propeller arms are mounted. Cams are mechanisms that are used to change one type of motion into another -- In the case of whirligigs, the motion of the spinning propeller and hub is changed into the action of the whirligig, usually by moving a connecting rod.
Before you construct your whirligig, design the type of action that your whirligig will portray. Some popular designs include fish with spinning tails or bird with spinning wings. These types of whirligigs consist of blades mounted on a central hub. More complex whirligigs that incorporate cams include kicking animals, or humans that chop wood or rake the dirt. These whirligigs are constructed with jointed parts. The wind turns the propellers, which turns the cam. Then the cam moves the connecting rod that pushes and pulls the wooden man or kicking animal.
Draw out your design to scale on graph paper. Use this design to deconstruct the wooden parts. Cut the parts from plywood, and shape them using a jigsaw and sand paper. Drill holes for the jointed parts and fasten them together using pins. Paint them and assemble the rest of the whirligig using wood glue. Attach the connecting rod to the moving parts of the whirligig. Then attach the propeller to the hub. Mount the hub onto the cam. Attach the cam to the whirligig. Finally, mount your whirligig onto a stick.