There is a research project here at NYU for which I am planning to build a little custom-made robotic mechanism. One of the key components of this mechanism is a “worm drive”. Worm drives, which you may have seen in toy cars, are useful when you want an easy and compact way to gear down the rapid rotation of an electric motor into a rotation that is a lot slower but more powerful.
The general idea is to attach a threaded screw to the shaft of your motor. As the motor rapidly turns, the threads of the screw (being helical), seem to gradually drift up or down the shaft. This drift can be used to transfer power from the rapidly spinning motor to a slowly turning gear.
This weekend I used my little home-brew software modeler/renderer to make a 3D computer graphic mock-up of one of these things. I spent way too much time on it, partly just because it was fun, and partly because I ended up being quite taken by the sheer aesthetic beauty of this mechanism.
If you click on the image below you will see an interactive Java applet that shows a worm drive in action. The applet also will also let you zoom in for a close-up:
Individually, the two parts of the drive are rigid, yet the effect when they move together is surprisingly sensual. There is something strikingly intimate about this dance between two very different yet perfectly synchronized shapes. You could say they were meant for each other.
Lovely! (And also a perfect example of the work as play approach that we were talking about earlier.)
Other wonderful things that are helical:
Barber pole, uses motion like a worm gear but just for a beautiful visual effect.
Parking garages, to pack space, use a double helix, so very hard (for some of us) to understand! I finally, only this year, realized that when you lose your car you have to transfer over to the other helix to look for it there too.
Now that I mentioned the double helix, just remembered DNA…