By heinzdrei heinzdrei.wordpress.com/ Follow
More by the author:
a Zero Budget: Quick and Cheap Ghost Illusion" width="" />
About: I love tinkering with about anything in the rare spare time I have, and when my wife and three daughters let me. I'm particularly interested in 3D printing (DIY Kossel printer), electronics (amateur with a lot… More About heinzdrei »
This magic cauldron was built in preparation for the birthdays of my two older daughters -- like many children they're both extremely fond of the Harry Potter novels and they both want a Harry Potter theme party. The cauldron has a very magical effect: inside, there's a bubble machine that blows bubbles upwards, as well as a line of UV LEDs. In combination with UV bubble fluid, in the dark you will see glowing bubbles emerge from the cauldron. As often, the effect is hard to catch on a smartphone camera, but it actually is really beautiful.
Now, there is another story to how I came to building this, and I think it's worth telling: last year, I constructed my bicycle bubble machine and published it. On thingiverse, a user commented that this machine would be really cool using UV bubble fluid and corresponding LEDs. I had never heard of UV bubble fluid before, I was intrigued by the idea, but my budget for tinkering was completely exhausted by my first 3D printer I had built that year. So I answered: I'll go for it somewhen, but, frankly, I'm broke. This read another thingiverse user, overflo from Vienna. He had a spare bag of 50 UV LEDs lying around, liked my machine and obviously likes to give back to others -- two weeks later, the LEDs arrived by mail, complete with corresponding resistors, a wired example and a helpful letter, because I had told him I'm rather an electronics beginner. A year passed by and I didn't get down to building something with the LEDs, until now. Well, it's not for the bicycle, I did face a lot of problems, I did a lot of mistakes, but I like my magic cauldron, despite all difficulties and shortcomings. And: I finally put overflo's LEDs to good use.
Please note: This instructable makes use of electricty and lots of fluids, two things that don't mix well. Really take care that you don't have the high voltages in the places where it get's messy, and make plenty use of heat shrink tube, isolating tape and similar things.
There was one huge obstacle to my magic cauldron idea: there didn't seem to exist any vertical bubble machine. Every machine I could find was working horizontally, which is due to the way nearly 100 % of bubble machines are constructed: you have a wheel with bubble wands, which dip into the bubble liquid when they're low, and pass a fan when they're up high. So what I needed was a vertical bubble machine. I could think of two ways of building this: my first idea was to use a belt system, with holes in the belt, instead of bubble wands. Using four rollers the belt could pass low through the liquid; the fan would be mounted in the middle of the belt.
Some things seemed complicated to me and I didn't have much time before our vacation and the wizarding contest deadline, so I setttled for a different approach: a classical Ferris wheel, again with the fan mounted in the middle. The vertical bubble machine uses a simple 80x80mm fan for blowing the bubbles and a small gear motor for turning the wheel.
The magical glowing effect is realized by UV-A LEDs that sit just under the edge of the cauldron, directed upwards, and by using a UV active bubble fluid, like its sometimes used at partys or discos. The effect is of course most impressive when it's getting dark.
While up to here everything worked like expected, my decision to make a cauldron of my own, first trying it with papier maché, then with plaster, really wasn't worth it. If you want to build your own magic cauldron, please consider the easy alternatives I'll mention when it comes to this step! Also for the LED stuff, there are easier ways which I'll mention.
If you want to build this cauldron, please first read the whole instructable before buying things needed -- while mine works, you'll want to do some things differently from me. I'll talk about this in the following steps.
Let's begin with the bubble machine. You'll need:
Now for the lighting, like I did it, you'll need either:
Or, if you think about my advice in Step 5:
And for making it all live:
Tools and stuff:
For the cauldron: I'll talk about this in the corresponding step.
