Constant force springs

There is some confusion about the "special springs" I use in my sculpture. The assumption is that they are a kind of spring motor that drives my sculptures at a constant slow rotational speed. What they actually provide is a constant rotational force or torque, not constant rotational speed. If the spring is not constrained in some way it will unwind very rapidly.

A traditional coiled clock spring gets "tighter" and provides greater torque the more you wind it. A constant force spring provides the same torque or turning force through out its cycle. You can find sources for constant force springs and much more information on their uses by doing a Google search on "constant force spring."

A good way to emulate a constant force spring is to attach a string to a freely rotating spool and hang a weight from the string. Wind the string up onto the spool, the torque or turning resistance you feel is pretty much the same as that from a constant force spring. If you release the spool the weight will drop and the spool will spin rapidly. You need to add a mechanism to control this rapid unwinding. My sculptures are essentially mechanisms to control the rapid unwinding of a spool. The general class of mechanism is called an escapement. Spring and weight driven clocks also use escapement mechanisms.

Clock escapements are designed run for long periods of time at a regular pace. I design my escapements/sculptures to produce visually interesting and sometimes random patterns. The important point to understand is that I don't power my sculptures with an escapement mechanism, my entire sculpture is an escapement mechanism.