Eagle and Gerber Files
Addendum:
We submitted the files to pcbexpress and they said that the .drl file was not the NC drill file. I had to run the excellon.cam job file to generate the .drd file.
Recently I had to use Eagle to adjust a colleague’s PCB layout. To install it on a Mac, first download and install X11. Next download Eagle from cadsoft and uncompress the file. You should now see a directory. Inside, there’s a readme.txt file that tells you to run a bunch of commands in the terminal so that you can use the ‘install’ script that’s in the directory…but immediately following these commands it says:
NOTE: the installation procedure described here is not mandatory.
You can just extract the TGZ archive to any location of your choice
and use it there directly. All the ‘install’ script does is to copy
the program and man-page to the default location and set up a
symbolic link to the executable in /usr/bin/eagle.
So, just copy the directory to your /Applications directory and you should be set.
Now (drumroll), in order to run Eagle you first have to start the X11 server. After X11 is up and running, double-click on the ‘eagle’ file in the ./bin directory in Eagle’s main directory. That’s it.
After creating your schematic and pcb layout, you need to generate the appropriate files to submit to a PCB manufacturer. Most of these places will require Gerber files. I’m submitting my designs to PCBexpress and I found these easy to follow directions on their site…to generate Gerber files from Eagle, download these .cam job files and follow these instructions.
These .cam files will generate the appropriate Gerber files for you to submit. For a two layer PCB (traces on top and bottom), you’ll use E1.cam or E2.cam. Here are the files that are commonly generated with the .cam files downloaded from pcbexpress:
.bot – bottom traces
.top – top traces
.bsk – bottom silkscreen
.slk – top silkscreen
.smb – bottom solder mask
.smt – top solder mask
.drl – drill tool file
Happy PCB designing! There’s something satisfying about laying out component and solving the puzzle of connecting them together without crossing wires. 
