Ths week's assignment was to make a FabISP in-system programmer Specifically, I made the Hello ISP design variant that uses a resonator rather than a crystal:
The first step was to mill the board using the Modella mill. This was my first time using the Modella. My first board went off without a hitch.
However, after (spoiler alert) my first board ended up having problems at the soldering stage, my future millings weren't so clean. I ran into a number of issues with the height being uneven on the milling plate. After a few botched PCBs, I started to delve into learning how to properly test the z height at multiple points. The final board I ended up using still had some imperfections (you can see some improperly-cut space at the top of the board), but since that part was just covered up by the USB port I anticipated it wouldn't cause any issues.
Next came soldering. I've done a decent amount of soldering, but never surface-mount. As someone with terrible motor skills, this was quite a challenge, especially the tiny tiny USB pins (you can see below my first botched attempt, singeing the USB connector.)
After completely soldering my board, I found it didn't work. Using a multimeter, I was able to identify which two traces had a short, but neither I nor my wonderful friends who assisted me were able to actually pinpoint the location of the short itself. So I went back to the drawing board (or, rather, back to the milling table) and simply started over with a new board. The second board went much more quickly in soldering. I quickly reached the point where I was able to program it using a FabISP created by a friend who took How to Make the previous year.