Vector path crosshatching (in Illustrator) to speed up laser cutting

Similar to an inkjet printer, raster engraving images with a laser cutter is very slow since the laser must scan each line. In order to save time, I developed a way to make vector engraved crosshatch fills that laser cutters can finish much faster. Instead of going over the entire area, the laser only needs to engrave the vector paths of the lines thereby saving copious amounts of time. An added benefit is a more consistent result since rastering large areas emphasize grain variations in the wood.

Although the concept is simple, it took me several hours to find a combination of steps that worked consistently in Illustrator. The problem is that Illustrator’s crop and pathfinder tools (at least for my version) only work on shapes, not paths. CS5 introduced a smart cutting tool that can trim paths at intersections however I don’t have access to this feature, as well as it being a manual process.

Update Jan 2016: added screencast of process in CS5 (no audio)

The solution I found was to use the Live Trace function after rastering a clipping mask —  a hack if ever there was one, but I take advantage of predictable anti-aliasing artifacts to insure live trace makes straight lines. The key is using the live trace function in 2 steps: once for each diagonal line direction so that there are no intersections. Finally, combine the 3 groups: left diagonal group, right diagonal group, and the outside outline.

I developed this method for a rush job that needed some optimizations to finish on time. It would be fun to make more signs and vary the crosshatch densities for different darknesses and effects, let us know if you want to make some with us: