Homemade Steam Engine
The steam engine has been around for hundreds of years. It works by heating water until it turns to vapor and expands—creating pressure that, when released, can be transformed into mechanical energy. In this project, you’ll build your own steam engine, which you can use to test some properties of steam power.
As projects involving fire go, this one is pretty tame, but please use caution. Older kids should be fine with adult supervision. And remember, even the most careful geek parents can get singed by steam as well.
Age range: 11+ (with adult supervision)
Step 1: Prep the Can
Use the scissors to cut a soda can horizontally about 1/3 of the way up, then fold down the cut edge. Careful: That edge is sharp. You might want to wear gloves. You can also put some aluminum tape over the edge for added protection.
Step 2: Secure the Candle
Melt some candle wax in the center of the bottom of the can. While the wax is still warm, press a tea light down on top of it, anchoring it in place. Make sure it’s well centered, as balance is important for the engine.
Step 3: Bend the Tubing
Measure out about 1 foot of copper tubing and bend it in the middle into two small circles, leaving the extra on either side. Try to keep the ends as even as possible. (It should look a little like those hand exercisers you can buy to strengthen your grip, which use a V-shaped spring.) This takes some finesse—the tubing is prone to crimping and breaking. Try warming it a bit in your hands before starting. Rolling it around a hard surface like the neck of a wine bottle will help get the shape right. The faster you work, the less likely it is to break. Trim any excess using needle-nose pliers, or simply bend it off (making sure not to crimp too much).
Step 4: Combine!
Punch a hole in either side of your can about halfway from the top, allowing enough space so that the coil of tubing sits above the candle where it crosses the inside of the can. (When lit, the flame will heat the coil.) You may be able to use a paper hole-punch for this, as the aluminum is not very thick. Slip each end of the copper tubing through one of the holes, from inside to out, pointing each of them downward. Make sure there’s enough copper pipe poking through on each side to hang below the bottom of the can by at least an inch.
Step 5: Create the Jets
Bend the extra tubing to a 90-degree angle tangent to the can, but in opposite directions. (Picture in your mind that jets of water are coming out of these tubes; if you hung the whole construct by a string tied through the coil, the jets would cause it to spin—which is exactly what it’s going to do!) The bent jets need to be at the bottom of the can or lower, to ensure that they’re completely submerged when the can is floated in water.
Step 6: Make It Float
Water time! Fill up your basin or bowl. And prime your pump. What does this mean? Well, you need to get water into the copper tube. There are a few ways to do this. You could hold one end under a faucet until water comes out the other, then quickly cover both ends and float the can to keep the water in. Or you could use an eyedropper. The important thing is to get the water in the coil, and the can into the basin with the jet ends submerged, so the priming water doesn’t escape.
Step 7: Ignite
Light the candle (this can be tricky, what with it sitting in water and all) using long matches or a long candle lighter. Make sure the flame is directly under the copper coil.
Step 8: Wait and Watch
You’ll notice a few bubbles at first, which is a good sign. As the copper heats up, the water inside will get warmer and warmer. As it turns into steam it will expand violently, eventually popping and sending the little vessel in circles.
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