Introduction: Make a Desktop Sized Air Dancer (a.k.a. Tube Man)

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Driving home from work one day, I saw one of those large outdoor attention grabbers that consist of a giant stick figure with flaying arms. It was advertising a self-storage complex and it certainly got my attention. I later learned these figures were called air dancers, tube men and that the very first one was called the Tall Boy.

These figures are very simple and achieve endless motion using a very simple principal. All it consists of is a fan or blower that blows air into a plastic tube made in the shape of a stick figure. The figure has outlets in the ends of the arms and the head.

In this Instructable, I show you how I made a desktop version on the cheap. I used a white plastic garbage bag and a 12V fan from a server power supply.

Step 1: Gather the Parts

You will need:

  • A high-flow computer fan.
  • A plastic trash bag.
  • A large piece of plywood or some other heat-resistant surface.
  • Blue painter's tape.
  • A soldering iron.
  • A metal or otherwise heat resistant straight edge.

The high-flow computer fan is the hardest component to obtain. All normal PCs have fans, but they don't put out very much air. The small 40mm high-flow fan I used came from a burned out power supply from a rack-mounted server -- these fans are small, loud as hell and put out quite the storm. Ask someone that works in a data center if they can scavenge one for you from the junk pile!

Step 2: Make the Air Dancer's Body

The air dancer's body is made out of a garbage bag. I used a the heat of a soldering iron to form the seams. The best way to keep the iron from melting right through the plastic is to cover the plastic with blue painters tape and then run the iron's tip over the center of tape. The heat melts the plastic underneath and (hopefully) forms an air-tight seam.

Here is the process:

  • Set down a large piece of plywood to protect your work space.
  • Stretch out the plastic bag over the surface, securing the edges with tape.

  • Measure the outside perimeter of your fan and divide by two to find out how large to make the opening of the tube.

  • Determine where you want the seams to be and lay down blue tape the entire length of each seam.

I recommend starting with a simple design, like a straight tube with no arms, but you can later attempt designs with varied number of limbs.

Using a heat-resistant straight-edge, run the tip of the soldering iron down the center of the blue tape. Run up and down several times to strengthen the seam.

Once you have finished all the seams, use scissors to cut out the air dancer's body. Cut on the outside of the tape. This will leave some material between the seam and the cut edge, but you'll eventually turn the whole thing inside out, so the extra material will be hidden.

Step 3: Mend the Leaks... There Will Be Leaks!

No matter how well you perform the previous step, your air dancer will leak like a sieve and you will need to find the leaks and fix it one by one.

I found that the best way to do this was to blow into one opening while using your hand to seal off different lengths of the tube. When you find a leak, repair it by laying down another piece of blue tape over the gap and run the iron up and down over it, just as before.

Repeat until you have a reasonably air-tight tube, then turn the whole thing inside out to hide the seams.

Step 4: Mount and Power the Blower Fan

Computer fans will typically have two, three or four wires. You want to hook up the negative side of the 12V power supply to the black wire and the positive side to the red wire. The other wires can remain unconnected. I used a 12V DC wall wart to power my fan, but you could use a benchtop power supply or a PC power supply.

You need to mount the fan so that it blows air upwards with enough room underneath to allow the air to flow in. I made a 3D printed jig to raise my 40mm fan of the table, but you could improvise with a dowel rod, toothpick, or even paper rolled up into tight rolls.

To complete your tube man, fit the body sock over the fan's casing and secure with masking tape. Plug it in and watch your tube man do a little happy dance for you!

WARNING: The blades on these high-flow fans spin very fast and hurt quite a bit if you touch them (guess how I found out?). The air dancer is not recommended as toy for young kids or pets.

Attachments

Step 5: Bonus: Control Your Tube Man Using an Arduino

If your fan has four wires, you can use an Arduino to control the fan speed. This could open up some interesting possibilities, such as varying the fan speed to make the Tube Man dance in a more controlled way, or to have it respond to external sensors.

A four wire fan has the following wires:

  • Ground
  • 12V DC
  • Tachometer
  • Speed Control

If your fan has two or three wires, you will not be able to control the speed easily (sorry!).

Identify the right wires:

The ground wire should be black and the 12V wire should be red. Confirm that the fan runs on straight 12V before proceeding. To prevent damage to your Arduino, only the tachometer and speed control wires should be unknown.

The speed control wire is safe to connect directly to an Arduino output, but the tachometer may not be. I used a 220 ohm resistor in series with the output as this will limit the current and protect the Arduino pin if I get it backwards.

So hook up one of the free fan wires to the breadboard as shown. You should only have ground and the speed control wires running to your Arduino. Make sure the positive side of your 12V supply is not going to your Arduino, as this would most certainly fry it.

If all looks good, load up the following sketch and power up the fan:

const int speedControlOutput = 10;

void setup() {
}

void loop() {
  // Slowly ramp up speed from zero to 100%
  for(uint8_t speed = 0; speed < 255; speed++) {
    analogWrite(speedControlOutput, speed);
    delay(250); // delay 250 ms, i.e. a quarter of a second
  }
}

If you are hooked up correctly to the speed control wire, the fan should slowly ramp up in speed. If it runs at full blast continuously, then you have the output hooked up to the wrong wire on the fan, move it to the other disconnected wire and it should work.

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