Thirty-five years later, I am that designer. And I’ve just learned the hard way that a DXF is not a recipe; it’s a sketch on a napkin.

The DXF didn’t know what was a cut path and what was an engraving. It didn’t know the material was 1/4" mild steel. It didn’t know the tool was a 1/8" end mill, and it certainly didn’t know that the machine couldn’t cut a sharp inside corner smaller than its own bit.

I walked the G-code to the shop floor on a USB stick—no floppy disks anymore, but the reverence was the same. The Haas VF-2 sat there, gray and patient, its spindle cold. I clamped down a 12" x 12" sheet of 6061 aluminum (the customer had changed their mind from steel to aluminum ten minutes ago). I touched off the tool, set my zero points, and pressed .