Back in the early days of New France, a coureur des bois would
spend a little fortune for his ultra light birch bark canoe.
Space era materials now abound in consumer products. The modern
backpacker will also find many opportunities to trade a large
amount of money for light gears. Every gram count. Tents have
carbon fiber frames, fork and spoon are merged into titanium
sporks, white leds provide dependable light sources, Gore-Tex and
microfiber enable light, warm, waterproof cloths. The outdoorsman
value light gears. It's part of his nature. It's enough work to
carry oneself over rough portage; who would want to carry a hard
The modern outdoorsman have it easy. His expeditions won't make
him rich, but he will find all his gears at the local store.
However, money won't buy him the ultimate stove. The ultimate
stove cost only 20 cents of supplies but one have to make it
There are many light stoves available to the backpacker. Propane,
white bas, hexamine, sterno, or just camp fire. One doesn't need
to carry a lot to be able to cook in the wild. When the coolness
of hi-tech settles down, backpackers agree that it pays to keep it
simple. The stove that packs the most bang per gram, that will
never fail, is so simple that no one wants to sell it. It's the
The extreme simplicity can be deceptive. There are several
variations on this basic theme and even if most serious
backpackers agree that the soda can stove is the ultimate stove,
the details of fabrication is the subject of heated debates.
Should one use glue? Is it still zen if you have a threaded
filler screw? Open flame or pressure jets? The Zen Stoves Website have detailed
instructions for many of the dominant designs. Here I want to
share how I adapted Robert Butler's Cobra Stove.
My variation retains the Cobra's simplicity in design while allowing
more refinement in construction to produce a good looking,
reliable and safer stove. I call it the Hannah Stove.
This is the design that I used with great success on the Kilauea and on the North
Shore of Oahu.
While I was experimenting with early prototypes, it became evident
that I wanted a pressure
stove. Pressure stoves are more fuel efficient and they have fewer
internal parts. I wanted something easy to build but most of all,
I wanted a method that would yield consistent stoves. After
learning the hard way, I decided that safety was to take
precedence over those two requirements. Building a Hannah Stove
will take you only one hour. Lets get started with the requirements.
At bare minimum, you will need
- 3 soda cans;
- 1 wood block;
- 2 wood screws;
- 1 box cutter (just the blade actually);
- 1 3mm drill bit (anything from 2mm to 5mm will do);
- 1 electric drill;
- 1 X-acto style knife;
- 2 sewing needle.
This is all what you need to get a functional stove.
To make your stove pretty you will also want to get
- fine waterproof sandpaper (600 or 1000 grit);
- polishing compound (yellow or green is best);
- buffing wheels.
This last list is for polishing. You could do it with steel wool
but that's a lot more work. With basic polishing equipment you
will have a shiny stove in no time. If you go for the shiny
stove, remove the paint from two of the cans before you open them.
Use the sandpaper for that. Be sure to smooth the bottom where
there is not paint as well. Use plenty of water to prevent the
sandpaper from clogging. Don't overdo it. You only need to clean
about 5cm from the bottom of two the cans.
Now would be a good time to enjoy a glass or two of your favorite
soft drink. You need to empty the two clean cans before you
Having a good time? So do I. Attach the box cutter blade on top
of the wood block so that it protrudes a bit. You will use the
wood block as a guide to achieve a neat cut on the can. This is a
tricky part. The Hannah Stove doesn't use glue or sealant. That
means that you need to fit the parts really tight. You can only do
that if the cut is really clean and straight. You will probably
need to use a spacer to adjust the blade height. Find something
to put either under the wood block or under the can so the blade is
about 2.5cm from the bottom of the can.
To get a real clean cut, you need to push the can firmly against
the wood block but only slightly against the blade. Technically,
the vector of your force should be almost orthogonal to the side of
the block and at most 20 degree against the blade. You then just
rotate the can until the blade passes through. This will take at
least 20 turns. You budgeted one hour for the whole thing, right?
The final cut should be really straight with almost no bumps
toward the inside. Minor bumps can be dealt with. When the blade
goes all the way through at one point, it might start to jam when
you rotate. You should be able to separate the two ends by
wiggling them gently without more cutting. I mean, really
gently; no bumps.
Once you have cut the two cans, it's time to assemble your stove.
The Hannah Stove is press fit. If you have peace of mind, you can
just align the can bottoms and fit one right into the other. It
is easier to do that if you enlarge one can bottom a bit. That's
what the third soda can is for. This can should still be sealed.
Select the can bottom with the less inward bumps, this will be
your stove bottom. You will ram the third can into it. The only
way to take the third can out afterward it to use vapor pressure.
Pour a few drops of water in your stove bottom and ram the third can
in it. Of course, when I write "ram", I mean "really
gently push downward". If it didn't get stuck there, you are
all set. If it did, pour a few drops of methanol in a pan under
the two jammed cans and set it ablaze. Both will just pop apart.
That or the unopened can will explode. It doesn't happen often
but for this eventuality you might consider replacing the unopened
can with a can filled with plaster.
Some people claim that packing some absorbent material in your
stove improves vapor pressure. Others say that it slows down the
pre-heating. Both are completely missing the point. Ultimately,
you want to use your stove in some unfriendly, and most likely,
uneven terrain. The benchmarks you make in your kitchen are nice
but they should not take precedence over real world usage. So,
imagine that your stove tips, and I assure you that it will. You
have a pressure stove and it will spit out its flaming fuel as
fast as it can. Also, you are bound one day to forget to put back
the refill cap. When you light up your pressure stove, the least
that can happen is an internal explosion. This will spray flaming
fuel all over the place. If you are unlucky, the stove will blow
up, spraying flaming shrapnels instead. Packing might affect the
performance of your stove, it might improve it or it might
decrease it. But, this is not why the Hannah Stove uses packing.
Packing is for safety.
The Cobra stove is clever with that regard. There is no
refill hole on the Cobra. The refilling is done through the jets.
The jets are small enough to prevent fire from entering the stove.
This has two problems though. The first is that refilling the
stove is really slow. You need to wait for the fuel to go
through those really small jet holes. The other problem is that
the stove is still vulnerable to tipping. Packing your stove with
absorbent material solves all those problems. If the material is
absorbent enough, tipping will only spill the excess fuel that is
not retained by capilarity. The absorbent package will also block
the filling hole from the vapor chamber. That way, you have a
large hole for fast refill and if you forget the refill cap, the
Hannah uses a coin instead of a screw, you don't blow anything.
You just get a larger jet. This jet will be too large to be
efficient and it will waste fuel but, that's the beauty of a
simple design, you can simply throw in your coin cap while the
stove is running to fix the problem.
So many words for a simple operation. To pack your stove, fill
the bottom with noninflammable absorbent material. I use
fiberglass insulation fiber. Perlite and vermiculite is also a
Before you lower the top of your stove over the bottom, drill the
filling hole. If you don't, the air pressure might disassemble
your stove before you are done, which is really frustrating.
Start with 3mm, you can always enlarge later.
By now, if your favorite soft-drink is the same as mine, you
should have peace of mind; you will need it for the next part.
This can be really frustrating but if you followed all the
instruction properly it will work, eventually. The top of your
stove is a little bit smaller than the bottom. You need to lower
it really straight into the bottom and to tap it gently until it
fits mostly flush. To get it started, you can cut a section from
the top a of can that you will use a guide. You need peace of
mind while assembling any kind of zen stove, but especially while
working on those that don't use sealant.
If you wreck one or both part, don't worry. You lost at most 20¢.
Just cut another soda can and try again, with peace of mind and a
stiff drink. When you finally get it, you can make the jets. The
easiest way to have the jets aligned is to use a hole model. I
made mine (SVG) with the star tool in
Inkscape. I set the number
of arms to the number of jets that I want and the inner radius to
0. The template
section of the Zen Stoves website has several ready made hole
How many holes you want depend on the size of your needle. A lot
of small holes gives best result. I use 24. Fix your hole model
on top of the stove. Blu Tack works well for that. Cut a needle
and fit it in the X-acto handle. To prevent the needle from
breaking, cut it so that it protrudes at most a few millimeters.
You can enlarge your holes later with a longer needle.
You are now ready for a test run. Your new Hannah stove needs pre
heating before it can build the vapor pressure that will sustain
the jets. All what you need to do is to pour a few drops of
alcohol in a pan beneath the stove. Go ahead, pour 30ml of
alcohol in the stove, a few drop in the pan, drop a coin over the
filler hole, and set everything ablaze. Wear protective gears,
too small jets will generate excessive internal pressure and can
blow the stove up. Note that using a coin prevent massive
pressure buildup. The coin just lift when pressure is to high. If
your stove does a few backfire like explosions, it's the coin
releasing the extra pressure.
Don't worry about boiling anything yet. Just study the jets. If
the jets are hissing and can't sustain a flame, they are too
small. If the flame is more than 10cm high, the jets are too big.
It is also possible that gas pressure is leaking from the seam
where the two ends are joined. It might be that there is a big
bump at that spot on either of the cans, that you removed too much
material with the sandpaper on the top part or that you enlarged
the bottom too much. It is easy to enlarge the holes but all the
other problems will require that you cut two new cans.
Once you are happy with your jets, you can see if they cook well.
With 24 holes, I use a 5.5cm high mesh pot stand. Depending on
your fuel type and your hole configuration, you will want to play
with the pot stand height. Making a pot stand will be easy. You
just need to cut a strip of steel mesh. Folding wire works just
as well. The idea is to play more with the pot stand because it
is easier to adjust that the jets. You new stove should bring
500ml of water to a rolling boil in 6 minutes with 30ml of
Once your stove is finely tuned, you should give it a good shine.
Aluminum is really easy to bring to a near mirror finish if you use
the right tools. The idea is to level the scratch pattern and to
progressively reduce the scratch size until you have something close
to the wave length of visible light. Check this quick
introduction by Caswell. Aluminum is a soft metal and your
stove is really small. You can move quickly from one step to the
next. With a little extra work, the technique you are going to use can
bring a motorcycle
frame to a mirror finish.
There are a many places where you can get your polishing compound.
Jewellers supply stores have a large selection at competitive
prices. For some reason, they don't like it when you tell them
you want to polish soda cans. Find an interesting story to tell
if you go see them. Wood working stores will also have some
polishing compound. Not a large selection but you only need a
medium one anyway. You can always fall back to Caswell.
They have all what you could wish for. Grab a medium cut, either
green, white or yellow and a buffing wheel. I also like to start
with a fast cut; black or brown is perfect. You should already
have smoothed your stove with 600 grit sandpaper. You might want
to give it another pass to remove any scratches that that occurred
while assembling. Rub the buffing wheel against the compound
block then against your stove. Change the angle for each pass but
try to keep it nearly perpendicular to the previous pass. Black
compound gives an interesting finish but it is yellow that gives
the real shine. To get a mirror finish, you need to smooth
everything with 1000 grit sandpaper and to get down to red or blue
compound, which I didn't do for this tutorial. When you use more than
one compound, start with the fastest cut and progressively move to
slower ones. Using more than one compound makes it shine faster but
your tiny stove will shine soon enough even if you have only a medium
You now have the ultimate stove. It is ultra light, good looking,
dependable, safe, easy to use, efficient and you built it in only
one hour, without fancy tools or measurements. Do not despair if
it doesn't work well or doesn't look good the first time. It can
take a few attempts to get it right.
This is a great how-to page. I found a similar one on Intructables.com, and linked to this page in a comment over there. The Instructables one uses a middle wall. I wonder what the pros/cons are for having it?