Prototypes

Prototyping is a big part of our process at Glass House Arts.

Sometimes it is tempting to thing that sketching designs on paper, doing some CAD, and running some structural numbers is enough, but prototyping allows physical interaction that is key to understanding how things will feel, move, assemble, and fail.

This page splits our prototypes into three categories: scale models, full-size mockups, and empirical testing.

Scale Models

Scale models shorten the feedback loop, allowing us to see and feel issues we didn't anticipate.

Balance

Scale-models of Temple of Floating Compression allowed us to explore different designs quickly. Maybe more importantly, it let us understand the balance of the piece, both physically (does it stay up?) and aesthetically (what should the relative sizes of the components be?).

Design

Scale changes things. While we had a handheld version of the tensegrity icosahedron, it turns out the dynamics are significantly different as things get bigger. With this scale model we learned that for this shape the tendons need to be fixed at the ends of the beams, while the common small examples are done with loops!

Fabrication

This quick model for Uplift was critical for figuring out how much of each cube can be constucted before they are assembled into the final chain. Because the finished product is ten feet long and hundreds of pounds, doing the welding and grinding on subcomponents is much nice. But it wasn't clear how much you could put together before assembly became impossible. Three different people had three different guesses, so we built a mockup to check.

Lighting

This phot might look just like Star, but it is in fact a 1:4 scale model made of steel. While we learned a lot about fabrication, angles, and strength from the scale model, a huge benefit was testing lighting. Because we never did a test build before Burning Man, this was our best opprotunity to write code for different lighting patterns, and see how they would look.

We made dozens of models and prototypes for Star. Here are three examples: bamboo skewer and hot glue, steel, and boba straws and 3D printed hubs and tips. Finally, the partially constructed final product. Each scale model served a different purpose: the earliest was small and fast, used for aligning on the project itself, submitting grant applications, and explaining the project to newcomers. Later, the steel model gave us practice, knowledge, art we could fit in our yard, and the testbed for our lighting. Finally, the boba version was special because it uses the actual hub and tip types the final did, but also because it was envisioned, designed, and built by a volunteer, showing the power of building art in the way we do.

Full-Size Mockups

Sense of Scale

We often build very quick and dirty full-sized mockups to get a sense of scale. Drawings, simulations, and scale models only tell you so much about what a space feels like. Both examples above are from Star. The left is the interior, and the right a single spike.

The spike was done to see if the finished product would feel impressivly big. Like, I know what 24 feet tall means, but it's hard to imagine what emotion will arise.

The moment the interior space was done, and we stepped into that blue dodecahedron dome, we immediately changed our minds on how the interior should be layed out. Instead of a cockpit it would be a plinth, a central monolith of screens. Without making the full-sized interior early in the process, we might have gone down a design path that we later would have scrapped.

CAD: Cardboard Aided Design

Left is the cardboard mockup of the Quadcycle, and the right is the final product. This is a case where some interactivity with the full-sized mockup is absolutely critical. How far apart should the bikes be? How big must the box where the pedals are be? Where on the bike frame can we connect?

Cardboard aided design can also help with much more simple cases - I love to use cardboard to design parts - for example the plate that connects two things: grab some scissors and cardboard - way cheaper and easier than cutting steel!

Empirical Testing

Load Testing

Yeah, you can model stuff in CAD and do simulations. But empirical load testing will tell us if those eBay "1,000 lb load" parts will really carry 1,000 lbs, or when our stack op of parts will start denting into a tube.

The photos show MJ, and the anvil with stand and hammers (over 600 libs) being suspended from a chunk of the material and the connectors used in Uplift.

Tensegrity Testing

The image shows our tensegrity icosahedron except where the steel cables should be there are 24 ratchet straps. We use this approach to figure out the exact cable length, how force distributes through the structure (using the inline crane scale shown above), and also how the structure moves. While the final will have stiffer steel, the straps are strong enough that we were able to climb the structure and even set up a hammock in it!

In tensegrity the tension members (usually called tendons) are responsible for holding the structure together, and the amount of pre-tension determines a ton about how their stiffness and they move. This tension is necessary, but the about is unknown before hand - it depends on how we want the feel of the object to be - more responsive? more resonant?

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