I didn't initially realize that I would run out of memory on a typical Arduino, so this was also a learning process. I initially planned to use a Nano, but ended up with with a Teensy. It arrived a day before the event. One of the many points in this project where I very narrowly and luckily avoided disaster.
Then the wild idea came: flip it upside down. This might seem like a simple solution, but I did not consider it for a long time because nothing about the design of the ball was meant to be supported from the bottom. The LED tube was supposed to hang from underneath the cap, which was meant to hang from underneath a rigging point above. Flipping the ball upside down would mean that these two connections which were previously simple cables in tension would have to be replaced with rigid supports in compression. Another complication was that the flange and cap parts were already ordered and printing, so redesigning them was not an option. I had to work with the cap and flange pieces I already had, which had interface holes that were designed only simply for cables to hang from. I had to rapidly design and implement a rigid support solution that would be able interface with these existing support points. The event started Saturday morning, and I had only Thursday and Friday to do much of the originally intended work on the ball and also make these modifications to invert the ball.
On Thursday afternoon, I paid a visit to Bill Brandwein, the stage operations manager at the Clarice, where the school's theatre department is. I used to work there building sets. I can't say enough good things about Bill. I tracked him down in the middle of his work day, started to explain my dilemma, and before I even got the chance to ask him for anything, he offered, "So want to borrow a boom base and pipe?", which is exactly what I wanted to borrow! How did he know! A boom base is a heavy cast iron base that a vertical 2" pipe screws into. Usually, it's used to support up to a few hundred pounds of lighting or sound equipment. It's black, subtle, and minimal, which I thought would be a perfect solution. It was also able to hold the ball 10 feet in the air, so the ball wouldn't obstruct any sightlines along the ground, even if placed in the middle of the show. Bill was incredibly generous and willing to loan out whatever I needed. In addition to the boom base and pipe, I also borrowed a flange to thread onto the top of the pipe to attach to the ball, and two 50lb sandbags to weigh down the base and make sure the ball doesn't fall on anybody.
I made three upside-down U brackets that would fit over and bolt to each of the three shackle tabs. Each bracket also had a top hole to bolt to a plywood disk. This effectively just moved the plane of the cap up and turned it into plywood, a material I could work off of. I made a few holes in this plywood disk to let power and USB freely pass through. From there, I screwed three L brackets to the plywood disk, and connected three scrap shelf brackets vertically to the L brackets. These three uprights fit snugly inside of the LED tube. I used three bolts through the tube to secure it to the uprights.
There wasn't much time left, but I spent some time considering. I opted to build a support structure to keep the ball from falling, which I initially really wanted to avoid doing for two reasons: the first was that it would obstruct visibility of the ball, since the ball would mostly be viewed from the bottom. The second reason was that I thought it would be complicated and difficult and I just would not have time. But there wasn't time to hesitate and I couldn't think of any other option, so I went to Home Depot and looked around for ideas. What I came up with addressed both of my concerns. It only took a bit more than an hour to implement, and it was an extremely minimal visible obstruction. It was simply three aluminum U channels bent up to support the ball. These three supports bolted to the bottom plywood disk, which also had the pipe flange and cap bolted to it.
The ball is filled through a screw-in valve using a shop vac. The valve was original to the beach ball, I just pulled out the threads from the ball and sealed it into the cap. The valve had a rubber gasket that provided a solid seal against the cap.
I got up around 10:00 and headed to the Armory, where there was a brand new air compressor waiting for me. It was loud. Fortunately, we had just enough air hose to put the compressor outside and run the hose and power out through a window. Also it was fortunate that it didn't rain that weekend.
The compressor ran constantly for the next 24 hours at a duty cycle of about 60 seconds on/30 seconds off. It may have been a little intense, but that little guy powered through it.
In retrospect, it's very fortunate that we were not able to hang the ball as initially planned. If it was in the air, there would have been no conceivable way to access it with an air hose. We would have rigged it, inflated it, and within an hour it would have been a very sad glowing sack hanging from the ceiling, and it would be totally inaccessible so it would remain that way for the entire event. Or, if I was smart enough to do inflation tests beforehand, I would have realized it was leaking, but I likely would not have found a solution and it would not have occurred to me to not hang it. Another advantage of it being on the ground was that it was closer to the people and more visible. It would have been easy to miss up on the ceiling, but only 10' off the ground, people were sure to see it and were able to interact with it around the base.
This project was the most intense exercise in high pressure problem solving I've ever undertaken. If there are two things I've learned from this project, they would be that it's critical to be more organized with communication, and if your project plans on containing air, you should probably plan on your plan not working.
So the ball is gone. Intense preparation in anticipation of of a brief but exciting show, then you throw it away. Such is the nature of showbusiness. I'll remember it with a mix of fond and stressed emotions.