Friday, December 19, 2008

Fabricated Growth Forms (Processing to Ponoko)

Like many others playing with generative techniques, I'm fascinated by the potential of digital fabrication. Getting beyond the screen and into the world of objects is a significant move for a field that has, until the last few years, reveled in its own immateriality. There's a lot to think about in this material turn, but that's for another post. Here, a quick report on my first experiment with generative fabrication.

I don't have a laser cutter handy at my workplace (though as William Turkel writes there are lots of good reasons why I should) so I decided to check out Ponoko; I wanted to see what was involved in generating, uploading and fabbing a small project. I started with the Processing sketch from Limits to Growth, and tweaked it to turn out much smaller forms (a few hundred nodes, rather than tens of thousands). I used the built-in PDF export, then opened the PDFs in Illustrator. (Illustrator is the only commercial/proprietary software step in this process, so I'd be interested to hear of any alternatives). The forms are drawn as linked line segments of varying stroke widths. Ponoko needs an EPS with only the outside edge of this form, so I used Illustrator to merge it into a composite path, then set the stroke colour and width as instructed (0,0,255 and 0.001mm).

The upload to Ponoko took a few tries - I was getting some strange errors as their system failed to "see" the cutting paths on the template - but after some swift and cheerful technical assistance it all worked. Pricing was also trial and error; the first design I uploaded was more complex than these, and of course these branching forms pack a long cutting path into a small surface area. I simplified the design, packed four forms onto a sheet, and opted for 4mm ply rather than acrylic. Final cost including (expensive) shipping to Australia was about $A60 (currently around $US40). Not what I'd call cheap, but not prohibitive either. There are intricate discussions of the economics of the business - shipping, exchange rates, local vs global, etc - on the Ponoko forums.

Eighteen days later, they arrived. Novelty counts for a lot here, but still, I'm totally charmed by these objects. A few surprises, but all good: they are smaller and finer than I imagined, and they smell very slightly of charred wood (excellent!). The cut edges are dark with a nice smooth, burnished surface, and the ply surface is clean. The scale and intricacy of the things seems to entice people to touch and handle them. I find them far more satisfying than the (much more detailed) laser prints I made with the same system.

Immediately it's clear how the fabbing process, and the materials, can reach back up through the production chain and influence the design and the generative system. One flaw in the design is a product of how I'm drawing the shapes: there are small rounded "shoulders" at the joints between line segments, caused by the overlap between one rounded line cap and the next segment - this is obvious in the physical forms. Better to draw the segments as tapered rectangles, and avoid the shoulders. Also, the branching topology is structurally risky; how to introduce more joins without breaking the generative model? This interplay, between computational process, manufacturing process, material and form, seems really promising. Ponoko seems to be an excellent, affordable way to try this out, and the built-in fab-on-demand shopfront is great, if you want to sell your wares. But it's still, ironically, working with a mass-production paradigm of one design, n copies. With hooks for a more dynamic, generative front end, it could get really interesting: designers like the wonderful Nervous System are doing this already. More documentation of the growth forms over on Flickr.