Fun with "Stick Bombs"
Stick bombs are made of popsicle sticks interwoven in such a way that pulling out any stick frees up all of them. Since popsicle sticks are springy, they can jump several feet in the air when they are released. I learned about stick bombs from Lunatim's amazing work with kinetic installations
. I've invented a new design of stick bomb... maybe you can invent another.
Here is a picture from Lunatim's site, showing how a stick bomb explodes...
Well, I thought this was so cool that I just had to figure out how he did it. And if you think it's cool too, you may want to build some of your own. I've invented a new design of stick bomb... maybe you can invent another.Wear Safety Glasses!!!
Lie on your back, hold your eye open, and drop a popsicle stick end-on from three feet up onto your eyeball... what, you wouldn't do that? Then don't lean over a device that can throw popsicle sticks three feet in the air, without protecting your eyes somehow.
Lunatim's stick bombs appear to be all built with the same motif. It takes just a bit of practice to build them, and I've learned a few tricks that I will now pass on to you. You will learn to build these two stick bomb designs, the first based on Tim's techniques, the second my own invention:
First hint: work on shag carpet. It's much easier than working on a smooth surface. You'll be weaving sticks under other sticks that are pressed down onto the surface, and a spongy surface lets you push down the stick that's going under, rather than picking up the stick that's going over. Also, carpet fibers will get trapped between the sticks, anchoring the construction to the carpet, making it easier to adjust one end without displacing sticks at the other end.
Second, when two sticks overlap endwise, overlap them a lot--an inch or more. The construction will be more stable that way.
Third, it may help to dip the sticks in warm water, especially when you're first learning. This will make them a bit less springy and slippery, so your constructions won't fall apart while you're working on them.
Fourth, build with a decent amount of precision; if the sticks are placed unevenly, the construction will warp out of plane, perhaps badly enough to explode prematurely. You don't have to use measuring instruments; you'll learn how neat you need to be, but it's quite easy to do it by hand.
Now, to construct a basic stick bomb:
Notice that the sticks are woven under and over each other. I've drawn arrows to show where a stick dips under another stick. Notice also that I'm holding down one of the sticks; otherwise, it would tend to pop up a bit, since it's levered over the right-hand vertical stick.
Here's how stick bombs are held together: If a stick wants to pop up, put another stick on top of it. If a stick is pressing into the floor, put another stick under it. So, first you extend the horizontal sticks, edges and center, on this principle. Add vertical sticks following the same principle: under the bottom-most edge sticks, over the top-most edge sticks. When the vertical sticks cross the center horizontal sticks, put the stick that's being held down on the ends (whether that's the horizontal or the vertical stick) over
the stick that's held up on the ends. That will spring-load them so they pop apart when they are released.
Pulling any single stick out of a stick bomb will release all the others; but with all the sticks in place, the stick bomb is stable. A stick bomb under construction is not stable, which is why you'll see me holding down one or two sticks in each picture. You will need to hold down the sticks with one hand while placing the new sticks single-handed. This may be awkward at first, but the carpet makes it much easier to get sticks under other sticks as needed.
So let's see what happens as I add sticks:
As you can see, the sticks are arranged in alternating segments, one where the middle stick wants to pop up and has to be held down, the next where the middle stick wants to press down and the outer sticks want to pop up.
So I can keep adding segments until I have a line as long as I want it. When I'm done, I just add one last stick at the end to keep the middle stick up or down, hooking it under/over the outer sticks which want to be down/up.
So how about those cool right-angle and T joints? To build a T joint, you just start a new row, hooking it under a stick that you will eventually remove to leave the joint open.
If you didn't remove that horizontal stick, then you could detonate the lower part without affecting the upper part--not what you want! It takes some care to slide the stick out sideways without disrupting the rest of the bomb, but work slowly, watch for sticks moving that you don't intend, slide it out a bit at a time, practice a bit, and you'll be fine.
OK, what about right-angle turns? They're basically like going straight, except that you don't put in one of the horizontal sticks, and instead you cap the end; then you start building the next row just like you'd expect. I capped it right away in this sequence, but you don't have to. Note that the viewpoint rotates 90 degrees between the first and second pictures.
So that's how you build Tim's rectilinear stick bombs. You can extend this to building quite large patterns, as seen in Tim's video of almost 2000 sticks being detonated. You can make the tracks cross each other; as long as the upper track detonates first, it won't disturb the lower track. (That's how Tim built the spiral that opened this article.)
But what if you're bored with rectangles? Well, you can try building 3D structures by sticking two tracks back-to-back. I did that, but it wasn't extremely satisfying... I'd still like to figure out a better way to take stick bombs into the 3rd dimension. In this design, the middle vertical sticks are pressing on each other, while the outer vertical sticks are pulling past each other, held in place by the "roof" sticks. It' still the case that pulling any stick will make the others disassemble violently, but it's a pretty flimsy construction, and only gets out-of-plane with a pretty shallow angle.
So how about... triangles? A bit of history first: while fooling around, I built a couple of rings and decided to stick them together corner-to-corner. So I pulled the corners apart and hooked the downward-pressing stick of one ring over the upward-pressing stick of the other, and vice versa.
But this is not a real stick bomb, since it's held together by its own weight: if gravity went away, the two rings would twist each other around until the sticks could slip, and the thing would detonate. In other words, each ring is trying to stand the other ring on edge; they are not really locked in place. (It does detonate quite satisfactorily, though.)
So I tried to think of a design that would have twisted corners, but would be stable. I finally came up with one, probably the simplest possible one... and it's triangles! See, instead of having the sticks that go into the corner pushed up or down by a large construction, just have them pushed up or down by each other. Use one additional stick to hold them in place. Let's take a look again at that cool triangular shape I promised to teach you how to build, and then a detail of its construction...
The shadow behind the full construction is there because I actually picked it up, stood it on end, and propped it there, without it falling apart. Stick bombs can be surprisingly durable. On the right-hand photo, you can't see it, but the two sets of sticks are torquing each other around; the top left and bottom right sticks are lifted into the air. When all six triangles are in place and interlocked, the twist is forced into a plane, spring-loading the entire structure.
To construct this, precision is required. Otherwise, it will twist out of plane unevenly and fall apart. It helps to make sure that every stick you place is exactly parallel to another stick in the previous triangle. When you get to the end, you have to join the last triangle to the first--and here you will be very glad you were precise, because you're not going to be able to rearrange the structure much to make the ends match up.
Also, I found it necessary to dip the sticks in water. (This caused them to bend and make the structure not very springy.) Perhaps a different brand of stick would work better. Finally, in order to keep the structure from twisting up and falling apart while you build it, you have to kneel on the first triangle while building all the others (or clamp it down, or put an encyclopedia on it, etc). When you get to the end, hook the triangles together.
So, I hope you've enjoyed this... perhaps it will even inspire you to play with sticks. It only takes an hour or two to get to where you can build 100-stick constructions in a few minutes, and amaze, or at least amuse, your friends, relatives, and loved ones.
Which reminds me: This is one I learned in college many years ago, and I always like to leave this in restaurants (assuming I'm eating with people nerdy enough to let me do it). It's quite strong--you can stack several pounds of glasses, plates, water pitchers, or whatever on top. Beware: if the foundation glasses are wider at the top than at the bottom, they may be tipped over if you put too much weight on the knives, so you may have to empty and invert them if you want to put more than one or two things on top.