Ask Blue_Nose

Thought I'd post a quick update on the recent Can-struction fundraiser/competition in which I again participated for the third year. For those who missed it, you can see our team's sculpture from two years ago and my topic on last year's build.

This year's design ever evolving, right up the the day of the build. The initial design idea was a Klein bottle, inspired by an amazing entry in the US from last year's build of a Mobius strip. Since it's not as well known, though, and doesn't look like much as a solid structure, we decided upon a similar-looking structure based on photo of a sculpture one of our teammates found online.

The sculpture's shape - an abstract curled shape - lead us to out final design, which was a spiral or spring, laying horizontally. During our first 'practice build', we attempted to create this spiral shape from scratch, but visualizing a three dimensional curved surface in two dimensional sllices proved to be difficult, and we didn't really get the results we'd hoped for.

It was my suggestion that day that we attempt to get some sort of formal design established before we attempt the build again. Without going into extreme detail (and thusly removing any shadow of a doubt the extent of my geekness), I was able to find an implicit 3D mathematical funtion for a helical surface, which I modelled in Maple, a math software developed in Waterloo. By inputting 'y' values in the equation shown below, I was given a 2D equation representing the contour of the surface at that 'y' value.

In the end, I had a collection of 'slices' of the shape (shown on the bottom right of the image below) I could use as each layer of the structure. These slices were traced onto large sheets of cardboard, which served to keep each layer level and also to give us a guide.



One very important note is that the cardboard was never used to structurally support a layer of cans - this is against the competition regulations. Cans were placed about half an inch beyond these carboard guides, and in any instance when a can had to stick out beyond the layer below, it was supported by means other than carboard.

Those means, for our group, were elastic bands - a ton of them. Some other teams resorted to using packing tape or plastic wrap to reinforce their structures, but we've always opted for our elastic band method, which largely conceals the way in which the structure is held together. This also allows us to decanstruct the model without damaging any labels or having to cut through layers of tape.

Our structure was built, as usual, out of tuna - approximately 1800-2000 cans of it. We had to order an extra 600 cans a few days before the build to make sure we had enough, which luckily we were able to pull off.

Anyway, this brings us to the day of the build. The whole thing went very smoothly, and there were no serious incidents. Some may recall the rather serious issue last year, which almost resulted in a collapse, but our structure was very solid this year, to the point that someone could probably stand on the top of it. I brought my laptop and webcam along to record a video of the whole things, and condensed the build into a short video. Unfortunately the quality on youtube isn't great:

[youtube width=400 height=350]http://www.youtube.com/watch?v=kqGtwcJThNg[/youtube]

The only issue I had was the fact that one of the officials kept coming over to us asking if we were concerned about some minor sagging near the edges - you'll see him come over with a 3ft level at one point near the midpoint of the video. I think he was mostly concerned with the issues we had last year, but it was more of an annoyance than I could personally stand.

Here's a shot of the final structure. Unfortunately there are much cooler views from other angles, but this is the only one I have at the moment. I'll post a few more when I get them from my girlfriend's camera.



We were all very happy with the results, and judging by the reaction we got, everyone else was as well. For some reason the judges were going to disqualify us, because they thought we must have cheated.

At the awards banquet last night, we were awarded with the People's Choice Award, which is based on public voting over the course of the few days they were up, as well as the Structural Ingenuity Award, which we always strive for. I was a little worried that we wouldn't get it this year, but apparently the fact that the judgesw were unable to see exactly how we did it was the trick.

As I mentioned at the beginning, this is my third year participating, and probably my last (at least with this team). It's been a lot of fun, and hopefully reading about it was, too!