This summer, we are going to attempt to cook entirely on a rocket stove, a device that consumes fuel so efficiently and distributes heat so precisely that you can boil a pot of water using little more that twigs and cardboard. If we get adventurous, we might try to build a solar oven at some point, but we are steering clear of the propane stoves and open pits cooking.
If you already have the tools, you can build your own rocket stove for less than $10.
You will need:
- A large metal container with a tight lid (for the outer body. square or cylindrical, doesn’t matter. Ours is an antique coffee container, a bit bigger than you would need)
- A stove pipe and and pipe elbow, 4″ diameter (this is the standard size. They are cheap at a hardware store, but also perhaps available at junk stores, lots or condo developments after dark)
- an empty tin can that measures at least 7″ around (an apple juice can would be ideal )
- ashes, for insulation (quantity will depend on the size of your outer container)
- an old over rack, or barbecue rack
Tools:
- tin snips
- measuring tape
- metal file
- thick gloves
- marker or pencil
- a hammer and chisel, or a hammer and nail
- can opener/serrated knife/creativity
1. Take the metal container and pick a side. If you have a cylindrical container, just start anywhere. Measure two inches up from the bottom and mark the spot. This measurement doesn’t have to be precise: decide what distance from the floor looks better on the metal container you are building on.
2. Lay container on its side with the marked side up. Place the elbow on the side of your container, lining it up with the mark. You are going to draw the 4″ perimeter of the stovepipe on the side of your box, centred in between the two sides of the box and a couple of inches above the floor of the stove.
3. Put the chisel, or the nail, on the circle that you drew on the side of the box. Start the hole by hammering the chisel through the side. Pry the tip of your tin snips in there and cut the circle out. You might want the gloves for this step.
4. Measure A and calculate B (A/2=B). This will be the first piece to cut off the stovepipe. Make sure the pipe is open, like in the picture below this step. Starting at the crimped end, measure B + 2″ up the length of stovepipe, and mark it. Make a line across the pipe at this mark. Use the tin snips to cut on this line (for us, it was a length of about 7″).
5. Fit the pipe together so it makes a cylinder. File down thee sharp tin. Push the crimped end into the elbow. This will be the bottom of your stove pipe.
6. Insert this “elongated” elbow into your tin container, and fit the long end through the hole you cut in Step 3. You need to do this in order to measure how tall to make the chimney of your stove. You might also have to file or snip down the hole in the big container, if the pipe doesn’t fit through. It should be snug, though.
Top view:
7. With the elbow resting in its hole in the stove, fit the other piece of stove pipe together (the length that was left over) to make a cylinder. lower it onto the upturned piece of elbow, and fit it on securely, but not too tight. Now, measure up this pipe and mark it 1″ BELOW the rim of the container. The chimney has to end while still inside the big container, so that when the pot sits on it it doesn’t block the airflow.
8. Take the chimney piece out, collapse it so that is it flat again, mark a line at the height of the mark you made, and cut with the tin snips. This is your chimney piece. Put it back into the elbow, and this time push it in good.
9. Set the body of the stove aside, for now. Open both ends of the tin can with the can opener. Use your tin snips to cut down the side, and use the hammer or your bare hands to flatten it into a rectangle. You need to make a t-shirt shape like the one in the pictures, with 1″ tabs poking out on either end of a 4.2″ wide rectangular piece. This piece will fit inside the bottom part of the stove pipe, to make a platform onto which you will be putting your kindling. It allows airs to flow up under the flame more easily. Like this:
I say to make it 4.2″ wide, even though the pipe is only 4″, because you will need to make sure it fits in tightly, and it is better to start with it too big than too small. Try it in, and trim some off the sides until it fits into the stovepipe perfectly.
10. Now, the lid. If your lid fits OVER the lip of your container, you are in luck: just cut of the edges so that the lid is the same size as the mouth of the container, cut a stovepipe hole in the centre of it, and its done. It will eventually sit inside the container, an inch or so below the top of the chimney.
IF, however, you lid was like ours, and is smaller than the body of the container, then you’ll have to make some modifications. We cut the top of the box to, then cut the end off of that, filed down all the sharp edges, and improvised an extra attachment from spare stovepipe material that would sit underneath the main lid and fit more snugly around the chimney. Hopefully, you don’t have to do this.
11. Fill your container with ashes, packing them snugly around the chimney pipe. We got 6 grocery bags full of ashes from a woman in Waverley. She has a wood stove and saves the ashes to use in composting, but she had extra. You will need ALOT of ashes if you have a big beast of a container like ours. Keep the inside chamber free of ashes.
12. Put your lid on, over the stovepipe (you did cut that hole, right?), and packing down the ashes, until the lid rests just below the top of the chimney. As you can see, we don’t quite have enough ashes to fill it yet, so our lid is resting a little low.
13. Set the oven rack resting on the lid, or on the sides of the stove.
14. Light a fire at the ends of some long, slender sticks. Push them into the stovepipe entry, on the top side of the tin can divider. Push the flame in to the end. They will burn slow, and the heat will be concentrated by the insulated chimney and the small space. Put a pot of water on the oven rack and see how long it takes to boil. Hopefully, not too long! As the sticks burn, you keep pushing them in so that the flame is always burning at the elbow bend.
And… bam! You have a rocket stove. Now you can celebrate your achievement.
