There are actually two separate CAD models that are superimposed to make up each grill, a “bold” grillwork which is thicker and load-bearing, and a “fine” grillwork which makes up the spider web. While the bold grillwork is swoopy and variable in cross-section along any given tendril’s length, the fine grillwork cross-section is all a oval measuring just 1.5mm x 2.0mm. Here is an image from when designing the fine grillwork, the idea being to combine waves in a pond with guitar waves:

After the grill design was finished, a set of aluminum master grills were CNC’ed out of solid aluminum for an un-godly amount of money, but there was no way around it. To machine the aluminum masters, one side was machined down to the parting line with a 3mm ball end mill being the final tool. Then the half-machined block was filled with clay, flipped over, and the back side machined down to the parting line.  The clay was used to prevent “chatter” of the work piece while all those fine grills were being milled.

The dimensions and pitch of the grillwork were pretty much guesswork, and the aluminum masters were about as stiff as WW 2 German helmets and totally lacking in resonance, which chilled my soul with the fear we had missed the mark with the design. But that was the only design we had, so we had to work with it. Several state-of-the-art carbon-fiber fabricators were approached to see about making the grills for us, but every one we showed the aluminum models took one look at that fine grillwork and said forget it. The state of the art with carbon-fiber was to make tubes or laminated structures. No one had ever seen grillwork like this or had a clue how to make it. We were on our own, and we would have to figure out for ourselves how to make something the likes of which had never been made before.

Starting at absolute zero, it took several months of steep learning curve to finally be able to make our own molds and grills like the one shown above for the treble grill. The basic process involves taking short yarn-line strands of carbon fiber, dragging them through an epoxy puddle, squeegeeing them, and stuffing them into the grooves of the mold. It takes two people about an hour and a half to fill the mold, one cutting and gooping lengths of carbon fiber in epoxy and handing them off to the stuffer with some big wooden tweezers. The stuffer gets to do the fun part, laying the fiber in the mold, gradually building up a woven structure with intentional strength patterns. It is also messy and pretty toxic, so all the work is done directly in front of our sophisticated air filtration system.

After the mold is filled, the lid is put on and clamped overnight. Each clamp applies about 75 kilograms of force, so the mold has about a ton of force on it.  The tighter the squeeze, the thinner the flash on the part when you take it out of the mold. If you look closely you can see plastic tubes coming out of the top of the mold and ending in a clear one-quart tub. These tubes are to allow excess epoxy to escape from the mold from various points in the mold pattern.