In this series, "Letters from the Fab Academy," Shawn Wallace, member of AS220, the Providence, RI community arts space, shares his experiences with the Fab Academy, a distributed learning collaborative built on the infrastructure of the Fab Lab network. - Gareth
Making and programming circuit boardsBy Shawn Wallace
Our assignment this time around was to design a circuit board, mill it, and program it in Assembly language. Each student had to become acquainted with the following work flow:
- Designing the board
- Machining
- Stuffing components
- Programming
Makeda Stephenson in the Providence Fab Lab
In a Fab Lab, circuit boards are either milled from copper-clad PCB stock or cut on a vinyl cutter from copper tape with conductive adhesive. We try to avoid the etching process in order to limit the used chemistry we have to deal with. Whether etching or cutting, the first step is to choose one of the options for creating a tool path to send to the machine:
- Draw the circuit as a black and white PNG image and bring it into cad.py for tracing.
- Draw the circuit using Eagle, a free PCB drafting tool, and export Gerber files, a standard format for PCBs. Gerber files can be converted into PNGs using gerbv or the online tool from circuitpeople.com. Bring the PNGs into cad.py for tracing.
- Draw the circuit in Eagle and use Eagle's CAM processor to generate mill and drill files that can be sent directly to the machine. This process was described by Marc Boon in a workshop at the Amsterdam Fab Lab in 2008.