Lightbar Rising …

January 12th, 2009

1/12/09

Watch this space!  High-rise coming soon!

This year, our seasonal affective disorder treatment center is relocating from a 40′ tetrahedron to a 32′ hemisphere — leapfrogging all the other platonic solids!  Corners are out, curves are in!

And so I get to build a geodesic dome — a rite of passage for architecture nerds.  I’ll be using Bucky Fuller’s famous bamboo plan, creating a 5/8 dome out of 170 sticks of bamboo and some duct tape.  This design works with the flexibility of bamboo to avoid the need for fancy joints.

I tried to build the same dome several years ago, but failed in unexpected ways: my knots were too tight, and I attempted a fairly small dome from fairly thick bamboo.  The internal tension tore the thing apart, and then the knots caused the bamboo to kink.  But this time, longer poles will flex better and duct tape will be more forgiving (and cheaper) than 550 cord.  Or not … let’s find out!

I have no idea if this dome will be strong enough for me to climb, but it ought to support my 40′ x 40′ white polytarp, which formed the skin of previous Lightbars.  Because I wore a hole in the center of it, it’s no longer suitable for tetrahedral use.   It’ll cover a dome, tho … albiet in a baggy, saggy sort of way.  I’ll probably need four smaller side-tarps as well.

I like duct tape for the joints because I’m an aspiring redneck, but also because lashing bamboo can be hard.  Bamboo has a natural waxy coating that resists the friction we need to prevent it moving around in a joint.  My initial tests suggest that duct tape will work great, but I do worry about it softening and unpeeling.  Fortunately, Lightbar takes place in the cold month of February.  If the duct tape shows signs of loosening, I may back it up with zip-ties.

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