I recently came across GearGenerator.com via a Hacker News post. It's a nifty tool for showing animated gear trains and producing SVG gear outlines. I found it can work with Big Blue Saw to make custom gears out of aluminum, steel, plastic, or other materials. Before reading this, you might want to review our article on waterjet cutting gears to get an idea of what to expect when waterjet cutting gears.
In addition to allowing you to change the pitch diameter, number of teeth, and pressure angle of each gear, the website will send you a gear outline if you click the "Download SVG" button.
Here's what the SVG looks like when opened in Inkscape. Most of this stuff isn't used when making the gear, so you'll need to delete all of the unnecessary text, the pitch diameter outline, and the filled area so that you're just left with the outline of the gear.
Once you have the plain outline of the gear, you can use Big Blue Saw's DXF Export for Inkscape or pstoedit to generate a DXF file.
The vector outlines produced by GearGenerator.com are fairly clean, so once everything but the gear outline is deleted, the resulting DXF file works well with Big Blue Saw's online quoting system.
If you need advanced features like rack-and-pinion or internal gears, there's another tool which I discovered. Dr. Rainer Hessmer's Involute Spur Gear Builder offers many more options.
What's your favorite tool for creating gears? Let us know in the comments.