From: Carl Worth Date: Tue, 5 Jun 2007 18:03:54 +0000 (-0700) Subject: Add balloon twisting entry X-Git-Url: https://git.cworth.org/git?p=cworth.org;a=commitdiff_plain;h=e68616d2c2a326eb5bc9664164784235bcd462c1 Add balloon twisting entry --- diff --git a/src/balloon_twisting.mdwn b/src/balloon_twisting.mdwn new file mode 100644 index 0000000..8f08843 --- /dev/null +++ b/src/balloon_twisting.mdwn @@ -0,0 +1,107 @@ +[[meta title="Balloon twisting"]] + +[[tag make]] + +Last Saturday, Kevin and Debbie staged a rather impressive backyard +carnival for Ethan's 5th birthday party, (inflatable jumphouse, +bean-bag toss, petting zoo, etc.). I was invited to volunteer as the +balloon animal guy. I'd never done balloon animals, but Debbie figured +"if he can fold paper, he can certainly twist balloons". + +## The Basics + +So I picked up some balloons a few days before the event and started +twisting. The basics were easy enough to discover: + +* Don't try to inflate the balloons with lung power, get a little hand pump. + +* Don't inflate the balloons all the way. + +* After inflating the balloon to the desired length, let a little air + out to make it more flexible and easy to work with. + +* Don't be afraid—just start twisting and see what happens. + +## The Party + +And it was easy enough to make some simple shapes, (poodle, wiener dog +and sword), without looking at any specific instructions. As it turns +out, the kids at the party were more than happy with these—and +there's definitely an advantage to sticking to models that are really +quick when there's a line of kids waiting. + +[[img balls.jpg size="297x150" class="left"]] + +I'd meant to do at least some googling and find something more +interesting to make, but I neglected to do that until just before the +party. So I didn't have time to look at more than one site. I learned +a baseball cap model there, and also a really intriguing volley ball +from three balloons (pictured here). It's slick because none of the +balloon knots or twists are visible—plus it actually works pretty +well as a ball for bouncing around in the air. + +I was feeling unprepared, so I kept twisting things in the car on the +way to the party, (fortunately, I didn't quite cause an accident—no +I wasn't driving, but the growing pile of balloons in the front seat +did start distracting Stacy while she drove). On the way I figured out +how to do a nice flower, (which, later at the party I made into a +flower hat), and I also invented my first original design—a frog hat +with oversized lips that can be squeezed to make it "talk". (Sadly, I +was too busy doing balloons to actually take any pictures that +day—and I'll have to figure out how to post video clips to do that +one justice.) + +## The Project + +Anyway, the party was a lot of fun, and I was glad I could help +out. When I got home I still had a couple of packs of balloons and I +was still intrigued by that ball design, and wondered if similar ideas +could be used to make something more elaborate. As with origami, I +seem to be drawn more to the intricate geometric models rather than +anything more organic like animals, (I think that's because my +non-artistic brain can deal with "fold in half" much more easily than +"fold at an angle that looks right for the beak"). + +My thoughts landed on Tom Hull's fantastic [five intersecting +tetrahedra](http://www.merrimack.edu/~thull/fit.html) origami design +which I'd constructed once before as a gift, (I'll have to do it again +and take a picture). So my pointless project for the weekend became +recreating the structure from balloons. + +I started by twisting each balloon into thirds, hoping I could get by +with just inflating 10 balloons, (2 each of 5 different colors). But +it was quite easy to see that balloons would be too thick at that +size. It was also really hard to weave each tetrahedron while having +to hold three different balloon segments to keep them from untwisting. + +So next I attempted with full-length balloons. This would require 30 +total, (6 each of the 5 colors), but would make it much easier to +assemble, since each beam could be threaded independently, (much like +the process with the origami model). But as soon as I built one +tetrahedron, it was plain to see that the balloons were too thin at +that large size and the whole structure would be far too loose, (but +the kids did like using the resulting tetrahedron as a playhouse for +the afternoon). + +[[img five_tetrahedra.jpg size="225x225" class="right"]] + +So the final structure uses 15 balloons, (3 each of 5 colors). Each +balloon is inflated nearly all the way and then twisted once in the +middle. This makes each segment in the final structure just short of 2 +feet long while the balloons have a diameter of about 2 inches. And +now that I'm typing instead of twisting, I actually went and read that +Tom's origami design also uses a 1:12 ratio. So I could have saved +myself some work experimenting by just reading that first. I did +consider solving for the perfect ratio before starting with the +balloons, but it's not easy for me to grasp the 3D geometries. Anybody +care to help me solve that one? Tom also leaves the perfect ratio as a +problem for the reader. + +It's really a beautiful structure when complete. A single picture +probably doesn't capture it very well. It's much more pleasing to be +able to examine it in person and view it from many angles. Also, +assembling the structure is actually a fun puzzle to solve, and I +think forces the solver to gain a new appreciation for some of the +symmetries inherent in the design. It had been 2 or 3 years since I +had done this in origami, and I really had to learn the model all over +again before I could get everything threaded correctly. diff --git a/src/balloon_twisting/balls.jpg b/src/balloon_twisting/balls.jpg new file mode 100644 index 0000000..99dbac7 Binary files /dev/null and b/src/balloon_twisting/balls.jpg differ diff --git a/src/balloon_twisting/five_tetrahedra.jpg b/src/balloon_twisting/five_tetrahedra.jpg new file mode 100644 index 0000000..34e5648 Binary files /dev/null and b/src/balloon_twisting/five_tetrahedra.jpg differ