Ghostfooting

critical reading for the rude

hexayurt models

E-mailed to the Hexayurt Google Group:

For the last week or so, I’ve been building hexayurt models with paper & scotch tape. I started with a 1 cm to 1′ scale — a neat and sturdy little thing. I built bigger paper models and noticed that the smaller paper models are sturdier than the larger. As the size of the paper structure grows, so do the weaknesses of paper begin to manifest.

I went to the hardware store (Home Depot), and checked out their insulation panels. I was there looking for Tuff-R or Thermax sheets from Dow, but they didn’t have that brand.

I went with R-Max sheets. The R value (and I just learned this) is the ability to resist heat flow; for R-Max 1/2 ” thick sheets (4’x8′ panel), the R value is 3.2… The Rvalue increases as thickness increases (5/8” = 4… 3/4” = 5). This stuff is international building code approved and is manufactured in Dallas (local to me). Cost $7.48 a sheet.

I bought one sheet, cut it down at the store into 4 seperate 2′ x 4′ sections. Once home, I cut it down further into 5 panels of 2’x2′, and (using scrap half-isoceles) into 6 triangles for the roof. I was missing one wall panel, of course, but this works as a door way. I duct-taped all the joints and seams, once I got the roof put together and centered on the walls. Whole process of cutting and taping took about 45 minutes, and that’s with taping inside and outside.

The R-Max model stands 3′ high.

The devil is in the details. Slight variations in angle, slips of the knife, or tension variations in the tape, can all change how the roof sits on the walls and how the walls sit on the ground. Minor variations can be corrected by slapping on bunches of extra tape, but this is to the detriment of stability and the ability to bear (its own) loads. In a larger structure, I can see how this could easily spiral into more significant problems and seriously decrease stability.

Other notes:

The thing is a friggin kite. It was an average, breezy, North Texas day — winds at abt 15 mph — and the hexayurt was trying to take off. Worse problem with full-sized version?

Tape tape tape!! tape!. The more the better, I reckon, but this duct tape looks like it’s already lost some of its adherence due to dew overnight… Moisture v. tape… But tape can work to make the thing tight as a drumhead.

Vinay responds: “…if the devil is in the details, salvation is in the tape!”

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April 2, 2007 - Posted by | making

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