In last week’s post, we started to make an alcohol stove, and got as far as finishing the bowl and burner ring. Today we’re going to make the inner wall, put everything together and seal it up.

Obligatory Warnings!

We’re going to be cutting bits out of aluminum beverage cans. They’re made of really thin metal, so the bits are sharp, and could cut you. Be careful! Also, tools are sharp too. Or pokey. Or smashy. They could hurt you too. Be careful! Also also, some or all of the tools and materials involved are known by the state of Cancer to cause California. If you follow these instructions and cut off your legs, don’t come running to me.

Making the inner wall

The final part is the inner wall. We’ll start by making a lengthwise cut in one of our scrap cans, then making a cut around the circumference of of the can. You’ll end up with a piece of thin aluminum as long as the circumference of the can and somewhat wider than 45mm, hopefully. If not, cut up the other can and make it wider.

About to meet Mr. Utility Knife.

Now, trim it to 45 mm wide, by first squaring one side, then marking the distance and cutting the other side to width.

This big!

We’re going to coil this piece of sheet into a coil. This coil is going to fit into the deepest part of the bowl, in that little ring that actually touches the table, and it’s also going to nestle into the same part of the burner ring. You can can coil it into the bowl, and mark the overlap. Cut off the excess, leaving about one inch (25 mm) excess overlap.

Next, we’re going to make a cut halfway across the width about a half inch (12mm) from one of the ends. Then we make a cut halfway across, coming the other way, on the other end. This should be the result.

Note the half cut is on the top on one end, and the bottom of the other.

Now we assemble it into a circle, like some weird bit of Ikea furniture, by interlocking the slots. Important note though, the excess flaps of material need to end up on the inside of the tube, not the outside. If they’re on the outside they interfere when you assemble the stove.

Note that the ends are on the inside!

Lastly, we’re going to cut some notches around one side of the wall to allow alcohol to flow from the middle of the can into the space between the outer wall of the bowl and the inner wall. I do three V shaped notches spaces more or less equally around, but one would probably suffice. I make them about 1/8″ (3mm), more or less.

Putting it all together

We need to do one more thing to the bowl: we need to stretch the metal around the top just a little, so the burner ring will fit inside. To do that we’re going to use a method called peening. Basically we’re going to sit the side of the bowl on something hard, and whack it with a hammer, preferably the round end of a ball peen hammer. Then we’ll rotate the bowl a bit, and whack a new spot.

Note the waviness of the edge at about 5 o’clock. That’s where I have been peening, and the metal is stretched.

We’ll work our way around, doing only gentle whacks, and see how it goes. It’s pretty easy to overdo this, so go slow and check often to see if the burner ring will start into the bowl. Once it does, stop, and pull the burner ring out.

Now it’s time for final assembly. First put the inner wall in the bowl, making sure that the notches in the inner wall are against the bottom of the bowl. Now fit the burner ring into the top of the bowl.

You will probably have to fit one side of the burner ring just inside the edge of the bowl, then try to work it in further and further around the bowl.

Almost there!

At this point it gets difficult to get the last little bit of the burner ring into the bowl. One of the scraps cut off from making the inner wall makes a nice shoehorn to help you along.

Work your way around, sliding the burner ring deeper into the bowl. Make sure that you guide the top of the inner wall into the recess just inside the center hole of the burner ring.

The key to the whole process is finesse. Eventually you should end up with this!

Assembled!

The final step is to tape up the seam between the burner ring and the bowl. That’s where the aluminum tape comes in.

First we measure the length we need and cut it off, thus.

I suppose you could measure the diameter and multiply by Pi, but I bet I get done first.

Then we trim the width a bit. We only need about a half inch (12 mm) width. A ruler and knife take care of that.

Perfection not required

Apply the tape over the seam. Aluminum tape has backing paper, so peel off an inch or so and stick it on, making sure you’re straight, and that the tape isn’t covering the holes in the burner ring. Then peel back a bit of paper, stick on the tape, and repeat until done.

Finally, burnish the tape with the cap of the marker to create a tight seal around the seam.

Congratulations! You now have an alcohol stove! Next time, we’ll make some accessories.

Crickey, ain’t she a beauty?