Out of all the mechanisms I’m designing for the showcase, the confetti tumbler is definitely the easiest one. Trying to find reference images on google, however, is a different story. Searching for “confetti tumbler” leads to hundreds of images of travel coffee containers with confetti sides. Confetti Snow Machine yields better results for an idea of how this machine should look and work.
The mechanism itself is simple - imagine a flour sifter. You put some flour in the sifter, and even though the flour is smaller than the holes of the sifter, friction keeps (most of) the flour in place. When you shift the sifter back in force, that motion causes the flour to separate, and some of it will fall through the holes of the sifter. Confetti is a larger and less fluid medium, but the idea is the same - if you create a sifter with larger enough holes, eventually a pile of confetti will sift through those holes.
Designing a large sifter though is impractical, but the same principle can be done cylindrically. Get a container, drill a bunch of holes in it, put confetti inside, and rotate. The pile of confetti will fall over itself, and some of it will fall through the holes. Rotational motion is incredibly simple. Stick an axle through the cylinder, put a gear or pulley on the axle, run some chain or belting, and voila, you have a confetti tumbler.
So now that the simple stuff is out of the way, let’s complicate things. The tumbler needs to work with the confetti, and confetti isn’t one-size-fits-all. You can find variety of material, colors, sizes, and even shapes online. So if I design a tumbler and the confetti is too small, the confetti can pour out of the tumbler like liquid. If I design the holes too small, the confetti won’t flow. So the first step is to pick a type of confetti to base the design around. The song demands “hellfire,” and so I’m in the search for confetti that comes in multiple colors (reds, oranges, and yellows), will sparkle like fire, and is a consistent diameter for each color. Enter Amazon with their randomly generated brands. 15mm, metallic foil, and comes in multiple colors. This will be the confetti I will base the design around.
(I do have hesitancies around foil. Since it doesn’t crinkle as much as paper, it tends to stick on surfaces because it will rest flat against the surface. It can also stick to itself for the same reason. The initial design will be based around this, but in case it fails spectacularly, I found an option for 1.5cm paper confetti that comes in similar colors.)
Now that we have the confetti and size, the next step is to start thinking design. As mentioned, the idea of a confetti tumbler is a cylinder with holes drilled through it. But here’s the thing - cylinders are expensive. A 6” diameter polycarbonate tube is, as of writing, $57/foot. But you know what’s not expensive? 3D printing.
Rather than buy a large tube, I can just print a cylinder for the fraction of the cost. It won’t be perfect, but it doesn’t have to be perfect - it just needs to be functional. And that is what I was able to accomplish this week: I printed an almost-tube.
The almost-tube is a roughly 8” diameter extrusion, roughly also 8” tall, with holes of varying sizes along the height of it so I can test how the confetti flows out. The hole diameters start at 1.5cm, and goes up 0.05cm for each group, up until 1.65cm. The almost-tube is called an almost-tube because 1/4 of the tube is missing. This allows me to, if I so choose, put dividers in the the almost-tube and still be able to fill it from the side, therefore getting an accurate measurement of how much confetti is sifting out of each section over time.
After printing the almost-tube, I took some of the confetti and sifted through it manually (using a trusty cardboard box to catch most of the confetti). It wasn’t a perfect fit, but I did have a successful sifting. I noticed that the confetti did stick to some of the 1.5 and 1.55cm holes, so I will use the 1.6cm holes as a baseline for actual tumbler design.
All in all, the print was 178g of filament, and at roughly $20/kg, this came out to only $4 in print costs. Substantially cheaper than a real cylinder!
I plan to continue working on the tumbler for this upcoming week. My goal is to come up with a design that will make the tumbler more rigid, modular, and rotatable by a machine.