Let’s face it, times are hard, and winter is imminent in the northern hemisphere. No matter how much you have to your name, there’s nothing like a cup of hot tea or a warm meal on a cold day. So if you need a snow day activity, consider preparing for whatever may come to pass by building yourself a complete hobo stove system out of empty cans.
[ElectroIntellect]’s stove consists of a 20oz can turned upside down with several holes made in the bottom for heat to rise. The smaller cans are used for cooking pots, and the smallest as a cup. The stove itself is meant to run on flaming twigs stuffed into the base, or a couple of tealight candles if you can only find green wood around.
This comprehensive guide covers everything from building the system to packing it up safely and taking it out to cook in the concrete wilderness. As a special bonus, [ElectroIntellect] brews up some hobo coffee on the stove using an old (clean) sock, and prepares a can of chili in under an hour with candle power.
Too much hardware for you? You can make a disposable rocket stove out of wood.
I made one one out of a small coffee jar, with a cover of thin soda can with a cross cut hole as a lid; a bit of cotton rag was pulled though the hole in the lid. This sat inside an old baked bean can with holes sawed into it, as a ventilation decice/support for a saucepan.
With the coffee jar full of vegetable oil, and rag soaked in same, I managed to boil water for coffee.
It took forever to get hot, but when the power is out and you don’t have an alternative, it made for an interesting distraction; and there was hot coffee at the end of it.
A-. Should have used a side cutting can opener. Not only are the cutoff lids not sharp, they can be used as lids for cooking. And they can be sealed again with epoxy for storage. Thus pull tab cans can be reused to store beans, rice, etc and not require a can opener.
I only learned of the side cutters a few years ago. They are awesome! $8 at Walmart.
You could construct a similar setup from deep-drawn stainless steel with no coatings. That would solve that problem. And don’t eat soy.
Don’t “tin” cans have a lining on the inside of them? Like a plastic coat? I know bottles like Snapple bottles have tin tetrachloride sprayed on the inside of them
Yes, please be aware of this these days. In the image you can see the color difference from the outside and inside. You really don’t want to eat that.
That lining should be epoxy. Yes, do not heat!
It depends on what was canned. Protective coats are common if the food was acidic (not to stop metal ions, to stop corrosion and food-poisoning).
Different areas often have different standards for the storage of food, with different liners. It’s a good idea to look around and use cans from foods that don’t require liners in your market.
For fuel, I’ve had good luck with vegetable oils, candles, candle wax, and various alcohols, as well as paper, cardboard, and wood scrap. They’re not all equally good in all conditions, and most of the time, what works best is a mixture of a hot/fast fuel and a cooler/longer-lasting fuel. One friend swears by shortening (vegetable or other). Apparently it works well with a candle or wad of paper/twigs, and if stored in sealed form, it has much longer shelf life as fuel than as food (but can be eaten in a pinch)
ALL combustion works better if you engineer the airflow to let the convection aid in combustion. Anything that lets the airflow gain and keep momentum will result in a hotter, more stable fire (but also increases fuel consumption; there ain’t no such thing as free (thermal OR metabolic) calories ;)
Your a bit mistaken. Plastic lining USED to be only for specialized acidic canned goods.. but now days >98% of all canned goods are plastic lined. Even beer and soda cans. A couple years ago I built some “buddy burner” hobo stoves with some scouts out of coffee and large beans cans.. and we had to throw them all out. They put off really nasty, toxic smoke that can both get inhaled and mixed into the food. Bad news. You can still use most of these cans of you first burn the hell out of them I a large hot bonfire.. them scrub them clean.. then burn and wash them a second time.. removing most of the toxic plastics. nasty stuff.. major carcinogens.
Literally, for 95% of the planet, a “20oz” can has no meaning at all. Is that like a coke can? Or a tin of Heinz beans? Or a big tin of paint? Good grief, I’m
British and in my 50s, but wrestling with imperial units (still less wondering if it’s a special US version) isn’t worth the mental effort of doing the conversion or even looking it up.
Oh, or are these fluid ounces, which is actually a measure of volume? Rats, I’m already getting dragged down this rabbit hole ;-)
Any chance we can standardise on the units (at least in brackets) that are normal for the vast majority of people who have access to Hackaday?
Yeah, it’s fluid ounces, but I gave up on that long ago. If the creator wanted someone to re-produce this exactly, they would just give the dimensions of the cans, and we could go from there.
That US “20 oz” can is a standard #2 size. If it’s important that be in SI units, it’s 87 mm diameter, 116 mm tall. OK?
I thought it was a joke when I heard about a #10 can (number ten can). I thought they were punning on the words “tin can.” It turns out that the #10 is about three quarts (2,84 liters)
The history of common weights and measures can be fascinating. And is almost always rooted in “what was convenient for commerce at the time”. Come to think of it, that’s a nearly universal aspect of the human condition. I personally was surprised to learn how many common standards derived from either Roman commercial or Roman military convenience.
Yeah, rocket booster the size of two horse’s asses, for instance – google it, stems from roman roads
And you can see a similar numbering system in cardboard boxes, or mailing envelopes.
Oh wow! So not only is the volume of a can measured using a unit of weight, but there’s a secondary unit for US cans which are simply numbers :-O !
Is there a mathematical formula for these Can #x sizes? Eg does each one up have twice the volume of the other?
It’s about 2 and a half demiards. Does that help?
Or approximately a kerfuffle and a half, give or take a spleefart.
Two and a half cups. But I bet the folks in tthe parts of the planet you are worried about are able to find a local can that meets the need.
Anyway, a #10 can (About 110 oz, 3 and 1/4 liters) is much better for cooking and boiling water and holding kit. A steel coat-hanger can make a dandy hook/handle for hanging it from a branch.
Tea cup or espresso cup?
How many people are actually going to go out and buy canned goods, just to get the right size cans for this? It’s more about making use of resources on hand. Canned foods are usually already cooked, and can be consumed cold. Heating them up, is just a luxury. Coffee can be cold brewed… Instead of a sock, I’d just go ‘cowboy’ style. Grounds settle to the bottom quickly, as it cools. Just don’t stir then up. This little cooker does have some uses, something to learn, but a proper campfire would do just as well most of the time.
Cowboy coffee recipe:
Throw a couple handfuls of Arbuckle’s into the boiling water in a coffee pot.
Boil hard for a couple of hours.
Throw in a horseshoe.
If the horseshoe sinks,
it ain’t ready.
I mean, if we’re gonna go with arbitrary units, why not the French ligne?
https://en.wikipedia.org/wiki/Ligne
It is about as large as a big mouse, or 160,000th of an elephant, if that helps.
Olympic Swimming Pool
500000 gallons
64000000 fluid ounces
1892705.9 liters
Therefore 20 oz ~ 0.591471 liter
What’s that in terms of a Blue whale’s bladder? We need relatable units common folk can comprehend easily.
And what is the cruising speed of said Blue Whale in Furlongs-per-fortnight (F/f)?
In the US Army there is an acronym that, if properly applied to all your questions, will resolve them: T.L.A.R. = That Looks About Right. Dont obsess about can sizes. Dont worry about side cutting either (cans are sturdier with the lip intact, and less apt to slice your kit bag when stowed.) Look for unlined steel cans that nest well. That’s all. I taught Boy Scouts for a decade after the Army. You can make a stove out of anything at all. We even had fire during a 24 hour downpour with 12 of flood water in the camp. (*and dry feet/hot food) using only a standatd weekenders backpacking kit. Fire can float. Biggest can you can find x2, use 1 as a chimney cap, other to float your volcano stove. The ‘hobo’ stove is very similar in design to a Swiss Army canteen stove. Those are aluminium and cost 10 to 12 USD. Oh, you will need a small platform (wire tent stakes work) and a drain hole just below the platform. You can use the tent stakes to lift it up and drain it if it floods.
Really? You can’t figure out “close enough” from the picture? How accurate do you need to be?
HaD is based in the United States. Seriously, do people from the US write comments on UK sites complaining about the units? Er.. actually.. I can picture that. Sorry if it happens. Please don’t do that guys! But is there a UK based site equivalent to HaD? Should I expect to find 20oz can projects there?
Anyway. Personally I wish the whole world used one system. Any universal system would be an improvement. Metric is not perfect but it’s probably the best currently in common use so if I ever become dictator of planet Earth I’ll pick that one. Are you holding your breath waiting for it yet?
Meanwhile do you really expect articles on US based sites to measure everything the same way you do? Let me show you a little sample of life over here.
https://www.kroger.com/search?query=can&searchType=default_search&fulfillment=all
See all those cans? What are the units? That’s day to day life here. We don’t control it, we just live in it. If someone told you to buy something in a #2 or 590ml and Kroger was your local store what would you buy?
Don’t get me started about fasteners. You Europeans have it made. So a HaD article talks about 20 oz cans. Boo hoo. Can you guess what the nuts and bolts isles of our hardware stores look like? Try building here in the US well.. pretty much anything from downloaded STLs that assembles with nuts and bolts. Sure they usually have a metric section but it’s usually tiny, under-stocked and way over priced. It hardly ever has all the parts one needs. Being cheap isn’t the only reason so many of us buy everything via the slow boat from China these days.
It would be nice if everyone who writes an article did the homework to convert all units to both systems. It would also be nice if every 3d design shared on the internet was parametric and easily switchable between common metric and sae fastener sizes. But well, making it so isn’t really a fun job. And we haven’t paid for it. How much did ElectroIntellect, the original author over at Instrutables get for this project? Did you chip in to fund converting to your local units? Did you pay HaD to do the conversion here? Nope? Well then free is free, take what you get.
>You Europeans have it made.
Until you have to deal with German Panzergewinde which is still specified in some piping and electrical connectors, or alternatively anything to do with hydraulics fittings which means dealing with a mixture of SI metric, American, Japanese, British, French… antiquated measuring systems and standards which do not fit together at all.
You also touch on the subject of why automatically translating from metric to SAE fasteners is a bad idea. You will turn up with parts that theoretically should exist, but cannot actually be bought anywhere.
“HaD is based in the United States.”
Ever heard of the World Wide Web? You can actually visit a website that is “based” in a different country. HaD has people from all over the world visiting and contributing. Since it is scientifically oriented you’d expect people to pay attention to units. The US, Liberia and Myanmar are the only countries sticking to Empirical units.
The trick is, it’s not important what “20 oz” means because you’re not really supposed to do anything with the information. Whenever numbers are involved in a casual news report or article, it is to create an illusion of relevance, like writing, “This wind mill can power 50,000 homes”, which is ill-defined and misleading anyways. How many elephants down the Mount Everest per year is that? I demand to know your pointless metrics of scale in units I am more familiar with!
If you don’t have 20 oz cans in your country, you use something else. It’s a tin can – not precision engineering.
Also, it’s 5.7 deciliters.
What, you’re not used to dl? Don’t know what it is? Oh, you must be one of those recently metrified countries where they insist that everything must be multiples of a thousand (no cm, cl, dl…)
We’re all fine with decilitres.
How about decimeters?
I absolutely think that elephants skiing down Mount Everest should replace MWh, good idea. :-D
An Asian Elephant racing down Mount Everest would actually be very close to 0.1 MWh.
“How many elephants down the Mount Everest per year is that?”
“You don’t get down from an elephant, you get down from a duck!”
-Groucho Marx
It most likely is not a tin can. It is either steel or aluminum. And it is weird to use weight to refer to volume.
Either way, you wouldn’t know how tall/wide the can was even if you had the volume in liters, so mentioning it is not relevant and complaining about the units when the numbers are not informative anyways is pointless.
Yeah, and I have actually travelled quite a bit & no, changing your units doesn’t suddenly cause liquids to start taking on standard dimensions according to their volumes instead of the usual taking on of the shape of the container.
@FC A fluid ounce is the volume of an ounce of water at some standard temperature that doesn’t matter. It’s a silly unit for the twentieth century but it’s not like it’s actually a confusing concept unless you’re being deliberately obtuse to irritate the yanks, which is a valid and rewarding hobby.
So your argument is that you’re too lazy to go on the internet?
Let’s sit with that for a minute.
Yes, cans these days have plastic liners inside, but in the presence of fire will burn off eventually although the smoke might very well be toxic. I’d think that this article needs to put in advice to burn off the stove first before use. And while it’s true that can sizes have numbers, not everyone has a key to which size can is which number. Going by fluid ounces on the label, or weight for that matter, can be deceptive because those vary depending on the can’s contents.
Case in point: regardless of contents, you could specify a #303 size can, and it would be exactly that size regardless of what was in it–but–the public at large has no idea what size of can that is, so you could say “find a can like what you find 28 ounces of diced tomatoes in” and convey the same concept. If you specify just a “28 ounce can”, you’ll frustrate a lot of people trying to hunt for that in the wrong isle in the grocery store.
Good points. I find the size of can doesn’t matter. The point is that these cans nest together so they don’t take up as much space as 3 separate cans. If you REALLY want to recreate this, just get some different sized cans that fit together. That’s the goal. Who cares what size they are? Make them as big as you care to carry and sufficient to hold your meal.
I was thinking from the standpoint of “…are used for cooking pots, and the smallest as a cup.”, boiling water or cooking other things in a can that might have a plastic liner in it likely is really bad idea if it degrades into the food. They aren’t designed for that. I thought of the things I could make with cans – in the end as you say, burning off any coatings for the fuel source part would be ok, and I think for the drinking/eating part an actual stainless cup would be better.
Although I suppose you could try and burn off the drinking/eating part in preparation for use as long as you got it hot enough to burn off everything completely.
Although it’s really not meant to be reused, the lining is in the cans when they’re sterilized – so it should be fairly heat stable.
Not an expert on canning in commercial business, but I would think that heating a thing to a temperature where they are boiling contents is way above the temp they use on a line, otherwise they couldn’t seal the can properly. Of course, they might do it after sealing the can – don’t know. But this looks like they use the small can as a cup which is heated above a fire. Meh, not worth the time I guess. On to the next life question…. :)
It seems baked bans are cooked in the tin can, see
https://www.youtube.com/watch?v=G6O2zTuGOVQ&t=90s
So anything less that frying should be OK.
I don’t know about commercial canning. With home canning getting the contents really hot is an important part of the process. That way when it cools back down it shrinks inside the now-sealed can and so creates a vacuum.
Still, I’ve seen people burn trash with cans in it. The coating does go away.
Yeah, a well washed hubcap would be better in every way. It could also double as a hat. Hobos don’t have enough space to be carrying around a bunch of single function items.
What sort of apocalypse are we envisaging where all the canned goods survive but all other cookers, fuel sources, and regular pots & pans are somehow raptured off the face of the earth?
Fallout, I guess?
One where you didn’t have a go-bag prepped before you had to GTFO from settlements & are mobile. And you’re still likely to have a hobo stove, simply because they tend to be light and versatile fuel-wise; I’m used to hobo stove designs that will run off alcohol…and manufactured camping stoves demanding specific, special fuel. That you are recycling doesn’t hurt.
Do you think your supply of portable propane tanks is going to outlast aluminum?
I have both done SERE school and since I have no family or friends outside the service, the psychology of going from ultra-competent to nearly useless, I did some time homeless after a medical discharge. Never any drugs, alcohol, or psychiatric issues beyond some PTSD just debt from cascading financial failures and inability to find work that I could do for 40hr weeks due to chronic pain while getting my VA file sorted out.
Hobo stoving or Dakota fire-holing a pigeon was an easy way to prep a dinner.
You can easily catch most birds and animals with a baited fishhook with the line run through a stake and a stick to finish them off.
Get the gutted and skinned bird to a good boil and add some salt, pepper, and select greens and you have a soup.
The nice thing about non-combat homelessness is nobody is searching for you with thermal so you can cook stuff if you can keep the smoke and smell down, bad thing is the cops use you as a punching bag and have no loyalty to homeless Americans even to fellow vets.
I used all of SERE school including the imprisonment and abuse training not for combat but to survive after I came home.
Anyways, the hobo stove writeup is pretty cool, I hopes it gets to people who need it but is mostly used for fun.
I have a few Hobo Stoves in storage and used them quite a bit back when I was back country hiking. They are very simple, light weight and usually you do not have to carry fuel with you, just gather twigs and such as needed. Beware of sharp metal edges when hiking with these as they can damage your backpack ( or fingers ). If using a camping cook pot also beware that the pot will blacken and soot up depending on the fuel used. I also have a Zip Zstove that has a small electric fan in the base to provide a more efficient burn. But for being a simple wood burner, the Hobo Stove is hard to beat.
Fun we made these in Cub Scouts. We used a tuna can with coiled cardboard potted in wax as the fuel source.
Depending on where you live keep in mind that starting fire outdoors without permission may lead you to fine from Forest Guard or Police.
This is some embarrassing rich-kid-cosplaying-poor shit. Tea lights? Really? You can do better with 2 soda cans, a razor blade, a nail, and cheap rubbing alcohol. Or just collecting sticks for a small cook fire. A cheap pot from good will rounds out the ‘cooking set’. Backpackers do it all the time. The result is lighter, takes up less space, and boils water faster.
This shows the process with extra tools:
https://www.youtube.com/watch?v=OvvdLVUJXZc
>Tea lights? Really?
Works perfectly well, easy, clean and safe to store, has multiple uses and burns a long time. One tea light is about 30-40 Watts of heating power. From my experiments with similar ersatz cooking methods, three tea lights will heat a liter of water to boiling in 12 minutes with a well-designed heater.
The trick is to surround the can or container you’re heating with tin foil to direct the hot air up the sides and reflect any heat back. You basically make a flue around a tall and narrow pot and heat it with the hot air rising from the candles. Otherwise less than 20% of the heat from the candles ends up in the water (as measured). When you get it right, it’s about 50% efficient. I used the setup in an experiment to distill drinking water.
And if you want to compare pound per pound, tea lights come in at 42 kJ/g while rubbing alcohol is between 22 – 33 kJ/g depending on what alcohol it actually is. You may have double the energy per mass in paraffin wax – the difference is that you can’t burn a candle as quickly, so you end up losing more heat waiting for the pot to boil, which is where the more efficient “stove” comes in.
Using more candles or more than one wick per tea light also solves the issue, but the problem becomes overheating the wax past the flash point and setting everything on fire.
Sorry, that was a deciliter of water – a teacup, not a whole liter.
It my distillation tests, I managed to boil off a third or a liter of water in four hours – which is how long the candles would burn – but I started with the water already heated to boiling. That’s how I estimated the 50% efficiency, because the input power was estimated at 100 Watts and the evaporation took 51 Watts, so the rest went up the flue.
You can also get a sack of 40 tea lights for $1 at Dollar Tree, making it a good bit cheaper than alcohol.
I’ve made a number of soda can stoves, slightly different from the design above. They work quite well; I used one to make coffee every morning, out on the Black Rock Desert in NV. As others have pointed out, it’s key to have some kind of windscreen to keep heat in. I cut part of the side from a larger can, punched lots of holes in the bottom (top now), set the pot on.
Have to carry alcohol—methanol is said to work best but both ethanol and isopropanol work—but that’s a minor inconvenience for short trips. Finding wood to burn at Black Rock would have been a 12-mile hike, at best…
Methanol has the lowest energy of the bunch. Isopropanol has the greatest, but it tends to burn with a long yellow sooty flame. Ethanol is somewhere in between. I wouldn’t carry pure methanol out to camping because of the risk of poisoning yourself with spills and the barely visible flame that you don’t see until you start pouring more fluid into the burner.
Methylated spirits is 90% ethanol.
You can simplify a bit and say a bucket of water takes a kilowatt to boil in an hour. That gets you in the right ballpark.
50 mills of ethanol contains about 1100 kJ of energy. One of those soda can alcohol stoves burns for about 20-30 minutes on a fill, so they put out between 600 – 900 Watts of heat. Way more than the tea candles, so it’s much faster to boil – but you’re much less efficient and you end up wasting fuel anyways because you always have to let it burn empty before packing.
I have made many alcohol stoves, and a few wood gas stoves. The wood gas stoves can be made from two different sized cans. The nicest ones are made from a 1 qt paint can and a Progresso soup can. The soup can fits snugly inside the paint can, on the inner lip. This type of stove is incredibly efficient, compared to hobo stoves. You can buy commercial stoves that use the same design, in stainless steel, for lots of money.
As for the alcohol stoves, yes you can burn methanol, but it is very toxic, and is absorbed through the skin, so be careful. In fact, several brands of hand sanitizer made in Mexico used methanol, and people were poisoned. Isopropyl alcohol burns very sooty. Ethanol is best. But don’t burn your good drinking spirits. Buy denatured alcohol at the hardware store.
A mixture of ethanol and isopropanol is the best, because it burns slightly longer and the flame is visible in daylight. Some say mixing in a dash of acetone will help with lighting the burner in the extreme cold.
This design served me well on a 4000+ mile lone motorcycle trip from WI to California and back. Cargo space was at a minimum and I used restaurants just 5 or 6 times over the 2 1/2 weeks.
This design is GOOD and no joke in the slightest. It’s especially great for backpacking (where I learned it from Boy Scouting far in the way-back times. Worked out on foot, and worked out on the bike…. with excellent performance be it twigs and sticks or a can of sterno in the desert.
A GREAT use for what you normally consider recyclable trash!