Woodgas Can Stove

This is a design for an inexpensive, lightweight wood-burning stove, suitable for backpacking, bike touring, and bush cooking.

It is a two-wall design, which preheats air in between the walls to ignite the smoke. Well-tended, this produces a bright, smokeless flame which produces little soot and leaves little to no scorching on the ground below.

It is built from commonly available (in the United States) parts: a quart paint can, a smaller tin can, and a shorter tin can. The only specialized tools are a safety-style can opener and an Irwin Unibit #1, though similar designs can be made with just a church-key and ordinary can opener and alternate tools are discussed in appropriate steps.

The whole thing can be built in about an hour. This model weighs 6.6 oz (187 grams) after several firings, and nests in, e.g., the Snow Peak 900 Ti or Al pot.

Ready? You'll need:

Step 1 Materials

A 1-quart paint can, with lid. I just bought a new one for a couple bucks at the local hardware store; if you're reusing one with paint in it you need to fire the paint off in an open fire. This is nasty and you're probably better off buying a new can.

A 19 ounce Progresso soup can. Other cans such as 20 ounce cans of fruit will work as well, but the
Progresso cans are a bit shorter, which we want.

A Large, short can. Mine had bamboo shoots in it; many cat foods and canned meats come in this sort of can. The diameter should be a little larger than the inner ring on top of the quart can. Don't get an aluminum one, it'll melt and buckle in the heat.

Comments

[akilbypup]

In making this good stove, I couldn't remove the tab-opening Progresso can lid with any of my can openers, because the rim is too high. Surveying available canned goods, I found another source for 19-ounce cans, measuring the same as the Progresso but with an ordinary top and bottom, in the ethnic section: La Victoria brand enchilada sauces (both red and green types) come in three sizes, including the one we need for this purpose. Just thought folks might like to know.

[Westmain]

Current link for the penny wood stove. Link above is dead.

http://www.jureystudio.com/pennystove/pennywood.html

[jimjola]

I built the stove!. Great instructions.
In the inside can I made two rows of holes on the sides and did a fair amount of perforation on the bottom.
I am definitely getting wood gas burning. However, I am also getting flames deep in the can.
I think I have too many holes in the lower end of the inner can. Is a large airy area in the bottom of the can too much?

[madpauper]

if you used the bottom you removed from the outer can and cut tabs in the inner can.
Then cut and bend the outer can bottom down so it would bend down and catch on the tabs you made in the inner can, also between 10 to 12 holes must be drilled in this piece.
Then bend tabs back up to secure the bottom you reused from the outer can.
Now you have a more efficient stove and easier to light and keep lit stove.

[bretta]

I made mine yesterday and tried it out today. It took 10 minutes to make a coffee. mind you I used your same inner can with a 1 gallon paint can, modified with 20 holes in outer can. Is this normal?

[rajmathur]

Please provide pics of where to put the burning material and maybe a video of it in action.

[jsawyer]

I made one, and afer one burn I had to use a hammer to take them apart.  Apparently the paints char up and act like glue...

[sarge89or]

Check out the original this guy tried to copy at this site:

tjamrog.wordpress.com/2008/12/22/the-evolving-backpacking-wood-stove/

I made one according to his specifications and used 3 sheet metal screws to make sure the two cans do not come apart.

[jasonm621]

When the inner can heats up wont that expand the metal, thus weakening the friction hold on the two cans? After one burn i would think a simple drop on a table would make the two can seperate... But of course i may be wrong...

[HAL 9000]

 I made one of these and its actually very tough. Believe me it does get hot, but the two pieces fit together so tightly and so perfectly, it's as if they were made to go together. I found that I had to hammer the two pieces together because they fit so tightly. i have used it on many occasions, from car-camping trips to wilderness backpacking,  and never worried for a seconds about the structural integrity.

[lentenaar]

You could have it burn better by adding a grill-type floor/level inside your burning can, slightly higher then the airholes at the bottom. This will have the fire air-fed from below. Making a more efficient burn, while ash will find it's way through the grill. The sticks will lean on the grill-floor which optimizes airflow. Your fire will reach optimum temperature a bit faster.

I hope this helps.

[rabagley]

The penny-wood stove (http://www.csun.edu/~mjurey/pennywood.html) uses a grid of much smaller holes all across the bottom and one optional ring around the outside. The lower they are, the longer/better each charge of wood will produce wood-gas, so on the bottom is probably the best location.

Ideal might be several big openings on the bottom and a wire mesh bottom dropped into the bottom of the can to spread out the ventilation manifold.

[YamiEridani]

Question, in your into you mention the use of alternate tools like a church key would be discussed in the different steps...have they not be added or did I miss them? Thanks, -Yami

[drew5337]

The top of the soup can fits into the inner rim of the paint can perfectly. There is enough friction to hold it in place. Its as though they were made to fit together this way.

[HAL 9000]

Wonderful! a cheap, easy to make, effective, and most importantly lightweight stove! put this together this afternoon, only i punched holes in the bottom of the inner can. i think once i make those holes a tad larger (the primary burn wasnt getting enough air, so it kept going out) this will be a great addition to my backpacking gear. as always, i have a suggestion to improve this method: rather than trying to press fit the cans together by hand (i tried but, ill admit, i wasnt strong enough) i put the cans, one inside the other, upside down on a table and placed another soup can on the bottom of the Progresso can. i then pounded it with a hammer untill the progresso can fit tightly inside the paint can. worked in seconds. thanks for the awesome design, i cant wait to go backpacking again!!

[kiwiiano]

May we have actual hole sizes, please. Irwin Unibit #1s aren't universally available outside of the US of A.

[atman]

The actual hole sizes are given, albeit in our funky, fraction based Imperial "inch" system. For those of you where things make more sense, let me interpret the runes:

1/4" = c. 6 mm NOTE: don't make holes this size, use:

3/8" = c. 1 cm for the inner bottom holes and the windscreen and:

1/2" = c. 13 mm for the inner top holes and the outer bottom holes.

Hope this helps!

[greggg]

Great instructable. On my inferior attemps at woodgas stoves I found using a small birthday candle was a good way to gently light the top of the twigs by using it like a match- the drips helping it to burn. Sort of cheating on the 100% renewable fuel I know, but convenient!

[schwieb]

Great tutorial, I seriously mean that. I do have a question about this step though. Everything else you did looks very neat and tidy, but here everything looks a bit ragged. This is not meant as a criticism. I was just wondering what happened. Is it maybe the cutting tool or the thin can wall or something? This might help me to select different materials when I build mine. Great work.

[atman]

Two things happened here... One is the can is a cheap Chinese piece of crap :-) hey, it got the bamboo shoots here, so it did its job! I even dropped it before I opened it, denting one of the sides slightly. The quality of the steel is one reason the holes are jagged. The other reason it's on the raggedy side is the tin snips I was using are the kind that look like a parrot's beak Use the kind that look like a robin's beak instead. Other people have had good results building the pot stand out of stainless steel mesh. Ordinary hardware cloth will burn through in a matter of days.

[static]

Fact is It's tough to drill holes cleanly in ANY sheet metal, that 's why holes in sheet metal in commerial production runs are generally punched. Expanded metal will last far longer than hardware cloth, but expanded metal can be very tough to work with. Not being critical of your project, but inserting food for thought for other's.

[pstretz]

This is a great instructable. I will be building one of these to take camping for sure. That being said, I think this may be misnamed. Wood gas is actually a completely different thing altogether. http://en.wikipedia.org/wiki/Woodgas This is more like a really complicated chimney starter. http://en.wikipedia.org/wiki/Chimney_starter I have actually cooked on my chimney starter before when quickly searing tuna and steaks and I can completely appreciate this design as a means to concentrate heat and cook things quickly and efficiently.

It would be interesting to pit a chimney starter modified with a potstand against this stove to see which would boil water faster.

[atman]

To quote the Wiki on the subject of woodgas: "Certain designs of stove, are in effect a gasifier working on the updraft principle - the air passes up through the fuel, which can be a column of rice husks, and is combusted, then reduced to carbon monoxide by the residual char on the surface. The resulting gas is then burnt by heated secondary air coming up a concentric tube. Such a device behaves very much like a gas stove. This arrangement is also known as a Chinese burner." That's the sort of stove this is! I hope that was clear. This stove is also not unlike a chimney starter.

[kat_man_2]

Can I ask what the reasoning is behind removing the bottom of the outer can? Would the stove not be more structurally sound if it remained on?

[atman]

Bottom of the can has to come off to allow the inner can to be press fit. p1pe you're probably right about that. They were what I had access to, though, and they do snip tin.

[p1pe]

Those tin snips suck because they're pruning sheers! :=O

[puppylinux]

(removed by author or community request)

[atman]

Efficiency is a tricky concept. A fan will make for a stronger burn under more conditions, at a penalty of extra weight, moving parts, and a battery which must be replaced or topped up from time to time. This stove doesn't need a fan, and properly built, fueled and fired is capable of a clean, mostly soot-free flame. Bloody Wesley, the 19 oz soup can locks into the inner ring of the quart paint can. It's a really neat hack; the inner can is held in place the same way the lid of the paint can is, by deforming the inner lip of the paint can to fit. Others have used more 'durable' fastenings, but I see no point; it takes real force to wedge that can in there. As mentioned in the instructions, using a rubber mallet to pound the lid on after press-fitting the cans will make the joint even tighter, though make sure you have a nice flat-head screwdriver or butter knife on hand to pry that lid back off!

[Bloody Wesley]

I don't really get how it locks into place or which end of the inner can is showing here in this pic. is that that the bottom of the soup can?

[rownhunt]

Finally theres a good instructable on this!

[guy90]

I spin fire now :) Thanks for the upload- seems a simple design, but ideal for the job- nice one! if you could lace the wood burning tin with a little fire cement, it'll add a little more weight, but it'll last longer- just a tip, if you ever wanna use this set up for drying clay, or art purposes.

[atman]

I've considered stove paint for durability; fire cement might be a bit bulky, which is more of a concern than weight, but a thin layer might well do it. Right now i'm going with the philosophy that a) most people building similar stoves haven't burned them out and b) soup cans are cheap. :-) If I end up with rust problems that may change.

[microman171]

Would you be able to get some photos for step 13? This was a great instructable! Keep it up! Makes me wanna build one!

[microman171]

Just watched the bush master video, and if yours is the same, then I know how to use it. It's great! I really want to build one now! I wonder if the local paint shops stock empty paint cans...

[atman]

If you're referring to the "Bushwhacker" woodgas stove, then yes, it's a similar design, although this stove is more like a BushBuddy or Tim Jamrog's can stove. I intend to take photos and video of the burn process, but first I'm going to make a new inner burn chamber and modify the instructable accordingly. Definitely want those larger holes at the bottom of the inner can sides!

[JeneretteP]

Don't you mean 13 and a quarter inch circumference? Diameter is across the widest point.

[atman]

Thanks! (This was in reference to step six, and was a brain fart; i got me basic geometry right in step 4. Corrected!)

[gbekks]

for nakigara, the intake holes on the outer can bring in air which rises up the 'chimney' created by the two tin walls to escape into the inner can through the upper holes in the inner can. the intake air also fuels the fire through the lower holes.
for putcork, try this image to see if it helps it is difficult to see but try looking around google images.
http://www.wikihow.com/images/thumb/4/46/Woodgas_stove_tin_716.jpg/180px-Woodgas_stove_tin_716.jpg

[nakigara]

ah, I feel rather silly now, I forgot about the upper holes in the inner can :/ thanx for the reminder/explanation.

[nakigara]

I have not actually built one of these style stoves yet, but have seen several different versions of plans for them. first- thanks for providing specifics as to what cans to use, picking appropriately sized cans can be rather tedious without info. second- out of curiosity, why did you put the intake holes at the bottom of the outer can? most other designs had them towards the top, so that the air would have further to travel before reaching the fire, allowing it to be more thoroughly preheated. As it is described now, the outer can looks like it is serving mostly as a windscreen. just curious. and thanx, nice job