Spiro Gear Drawing Apparatus

This project is what inspired my Gear O' Clock gear profile. A very simple continuous .075 radius. Formula below for making your own...

http://www.youtube.com/watch?v=VHtRhu262zk

Print out all or a few of the gears.

Grab a mechanical pencil, Sharpie Pen, or an similar fine drawing utensils.

Hold outer gear, place utensil in any one of the inner gears and draw many shapes.

Feel free to use my design to make any new gear designs you wish. I only ask that you share working ones and upload them as derivatives. The designs can be endless. Squares, ovals, rectangles, blob shaped and any combination can be made.

The diameter of the gear teeth is .15 inches. (See drawing.)
You must calculate pi by first determining how many teeth you want.
So basically 31 teeth x 2 = 62
62 x .15 = 9.3" which = The Circumference
9.3"/ pi = 2.962 which = the diameter to base your teeth off of.
The diameter refers to the pitch circle or center of diameter of your gear teeth.