Note: The Hobo stove has been rendered obsolete by the even greater simplicity and superior efficiency of the low tech Capillary Force Vaporizer stove.
To prevent forest fires many areas no longer permit campfires or cook fires built on the ground. Instead only a commercial cook stove is permitted. If you become destitute or otherwise find yourself in an emergency situation, violation of such a regulation may not be tolerated by well kept government officials who could care less about whether their hard boiled antics may be responsible for the skyrocket increase in arson and who will put you behind bars and feed you jail house food without a second thought.
If you have built a cook fire on the ground and find yourself in route to jail, just write a letter to your congressman and petition the government to provide anyone who is in need of cooking the food they have to eat or boiling water they have to drink, under any circumstance of desperation, with a free commercial cook stove and fuel for its operation versus locking offenders up in jail.
If you must cook the food you need to eat or boil the water you need to drink in absence of government understanding and assistance then a stealthy and disposable alcohol fuel stove may help keep you out of jail.
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Step 1: Prehistoric Man Could Have Built and Used This Stove
This stove is so "down to earth" (pun intended) that caveman could have built it using many suitable clays, especially clays (think about it) that contained aluminum ore. In fact if I lived near a clay deposit, I would use clay just to see how well it might work, especially if I could find no aluminum. I'd need glaze to make it leak proof and high temp clay to keep it from falling apart but that's another instructable I will not go into here.
As reality would have it my environment is inundated by pieces of aluminum foil (and your's probably is too), which has all of the needed characteristics so that is what I have decided to use instead of other materials.
If you can not find scrap aluminum foil you can always purchase aluminum foil at most any food store or a food product wrapped up in aluminum foil. The use of preformed aluminum cans to build a stove is already a well traveled road. Reserve aluminum cans for advanced stove construction.
What you will need for this instructable are three pieces of aluminum foil or whatever else your imagination can come up with that will do the job as well.
Step 2: Next You Will Need Forms - Just Like in the Army...
Not really, just kidding... you will not need to fill out any forms but rather to find or make the type of form otherwise know as a mold.
For your first stove you need to find or to make two or three cylinder type molds. After you have built several stoves a mold may no longer be needed and you can free form your stoves.
The first and second molds are somewhere between 2" to 3" in diameter and 2" to 6"s tall with straight sides. The second form should have a diameter that is about 1/4" greater than the first form. Tree limbs, PVC pipe or even pill bottles may be used to make forms or many other similar materials.
What you are going to make with these forms are different size aluminum foil cups with the first cup able to fit loosely inside the second and the third a bit larger or not needed at all.
If you use a stick or limb to make the forms then it can be flattened on the end with edges slightly rounded by whittling, scraping on a rock or by using some other method including mental kinesis if it will cause the aluminum foil to become shaped like a cup. Be sure that the first smaller cup will not be punctured by rough or pointy edges.
The third form needs to be a little bigger or about 6" inches in diameter and around 3" or 4" in tall. Its diameter and height will be determined by the weather.
Step 3: Construct the Cups
Ok, you have your forms and your materials so lets go to work.
You will use the first, second and third forms to make aluminum foil cups.
Once the cups are formed fold back the edges or use a pair of scissors or a knife to cut the edge of the first and second cups to make the heights of the cups about 1" to 1-1/2".
Make the second cup a bit shorter than the first by cutting off about 1/8".
Cut a circular (or other geometric shaped hole) centered in the bottom of the larger second cup about the size of a quarter or a little larger. You can increase the size after testing the results by burning a little alcohol. If you have enough pieces of aluminum you can use trial and error to find the optimum dimensions.
In the first cup cut out triangler sections about 1/8" deep around the top edge and about 1/8" to 1/4" apart. These will be the intake vents.
In the second cup cut out similar triangles about 1/2" deep and 1/2" apart. If you have a piece of aluminum that is big enough you can make its diameter a little larger than the cook pot and go all the way to the top instead of using cutouts for the exhaust ports.
Step 4: Assembly, Adjustments and Usage
Set the first cup on a fireproof base and away from any flammable materials.
Slowly fill the bottom of the first cup with alcohol. Check for any leaks. If there are any leaks recover the remaining alcohol and make another cup. Do this until the cup you have made is completely free of leaks.
Once you have a leak free cup put 3 teaspoons of alcohol in the first smaller cup and place the second larger cup upside down over the smaller one.
Use trial and error to find the optimal hole size of the second cup. Be prepared for rapid ignition (as in pop) in the event the hole you start with is too small. Light the alcohol through the hole with a long match. If ignition blows the top cup off or extinguishes the flame then make the hole slightly larger and repeat until lighting the stove does not cause the top cup to blow off the lower cup or cause the flame to go out.
After an optimal hole size is found build a support mechanism for your cook pot with rocks or bent coat hangers or any other suitable device so the cook pot will sit 1" to 1-1/2" above the flame.
You can experiment with all of the dimensions to find the best combination for your purpose. If its boiled drinking water you can use larger dimensions and burn more alcohol for a longer period of time. If its simmering you want then you may need smaller dimensions with fewer or smaller triangle cuts, etc. You can make many different stoves, each for a special purpose.
Set your target performance goal and reference to boil 2 cups of water with 3 teaspoons of alcohol. Use this reference to determine the amount of alcohol you need to cook or to boil different amounts of water. Adjust the alcohol amount to control boiling or cooking time.
In the event you see a person of authority (i.e., forest ranger) in a no non-commercial stove environment you can add water to the alcohol until the flame goes out, cover your cook pot and stove with anything that will hide it.
In the event you see weapons drawn slowly remove the cook pot, place your hands on top of your head and accidentally sit on your stove to turn it back into flat pieces of aluminum. (Do not hesitate to write your congressman following such an event.) ;D
As Smokey the Bear says: "Help prevent forest fires." and enjoy your disposable hobo stove!