I have been working on making gears lately and found the process harder than it should have been. I found some parametric equations for a 1/2 tooth involute and fillet profile here (http://eng-tips.com/viewthread.cfm?qid=272852&page=5) and whipped up a Java program to generate points in either a tab delimited csv format or an ibl format for those of us using CAD software. Gears can be generated in metric or standard.
EDIT: I updated the code to support profile shifting for gears with small numbers of teeth, as well as more descriptive prompts. Also uploaded sample output files for a 32 pitch, 20 degree, 32 tooth gear.
You will need the Java Developer's Kit to compile and run the code, freely available from Sun Microsystems
1.) Download the file Gears.java and compile it using %> javac Gears.java
2.) Run the file using %> java Gears
3.) Follow the on screen instructions
4.) Input the points into the design software of your choice
NOTICE: All software is provided without warranty of any kind. Read the source code before using. Run at your own risk.