Thursday, March 29, 2012

How To Make A Mini Methanol Burning Backpack Stove

   Mini stoves and fuel cubes are convenient supplies for any backpack adventurer, but these types of stoves tend to be flimsy and the small flame of a fuel cube is not the most efficient way to boil water. Fuel cubes are great fire assists though, especially the waterproof variety. In my research on more powerful, portable heating options I stumbled across Zen Alcohol Stoves. On their website they outline a variety of liquid fuel burning stoves that you can make yourself from aluminum soda cans, cat food tins, and arguably any metal container. I greatly appreciate their work and for offering this host of free information.

   I fabricated a handful of different designs and conducted efficiency tests. I found the low pressure, top-burner, 12oz aluminum can design to be my favorite, and I recommend fueling it with methyl alcohol, aka methanol, or more commonly known as gas line antifreeze (Yellow bottle “Heet”), which is inexpensive and burns clean with no smoke or odor. After sifting through the vast catalog of information on the Zen site to figure this thing out, I thought I would simplify the process for any of my readers looking for a reliable, lightweight camping stove you can make yourself.
Materials needed-
·         Two 12oz aluminum cans
·         J-B Weld
·         Metric ruler
·         Steel wool
·         Masking tape
·         Ridged angle
·         Scissors
·         Paper hole-punch
·         Permanent marker
·         Craft knife
·         Push tack
·         Sandpaper

-Download the template sheet from Zen and cut out the 40mm wide inner wall template and the #24 circular template.

*If you don't have a printer, no worries, once you see how these are made you can likely wing it with a fair amount of success.

-Use steel wool to polish the unopened aluminum cans free of paint. They’re much easier to polish while they’re sealed and full.
-Secure the craft knife to a ridged angle at 30 mm and score the first can.

-Secure the craft knife at 40mm and score the second can.

-Empty the cans of their contents and rinse clean.
-Use the craft knife to score the bottom of the 30mm scored can. Carefully score around the edge until you can pry the disc free. Discard the disc and use sandpaper to dull the sharp edge that remains.

-Center the #24 circular template over the opening and mark the line points with a permanent marker, keeping them close to the rim. Use a push pin to punch the holes.

-Use scissors to cut out the 30mm and 40mm can bottoms. Make sure to leave enough aluminum in tacked to layout the inner wall.
-Tape a leftover sheet of aluminum to a flat surface. Tape on the inner wall template and cut it out of the aluminum. Use the hole punch to punch out the three half-holes on the edge of the diagram. Only punch holes along one edge of the inner wall.

-Assemble the inner wall by folding together and locking the tabs, folding them inward. Apply J-B Weld to the inner and outer tab seams and along the rim of the inner wall opposite the punched half-holes. Seat the inner wall down into the inside rim of the 30mm can half. Allow to cure for 24 hours.

-Assemble the two can halves by inserting the top (with the inner wall attached) over the bottom half. You might need to make a couple small snips in the lip of the bottom half to help it slip under the top, or make a shim from scrap aluminum to coax the upper half over the bottom. Don’t worry about dents in the seam as long as they’re small enough to be covered with a seam of J-B Weld.

-Make sure the inner wall is firmly seated into the bottom half by gently twisting and pushing the halves together. Seal the outer seam with J-B Weld and allow to cure for 24 hours.
   *You can try to seal the inner wall tab seams, seal it to the inside of the top half, assemble the can halves and seal them together all at once, but I found assembling the two halves together a lot easier if the inner wall is already secure to the top half.

   Congratulations! You now have your own lightweight, compact backpack stove.
   Pick up a liquid medication measuring vial if you want to precisely monitor fuel consumption. My tests revealed that 20ml of methanol will burn for 7 minutes in this stove design. A standard bottle of Heet is 355ml, which gives you just over 2 hours of burn time per bottle.

   Carefully pour methanol into your stove and light. At first, a single blue flame will emanate from the main opening. After a few seconds the fumes in the inner, outer chamber will ignite and begin to burn from the pressure ports.

   Burning methanol is difficult to see unless shaded so be extremely careful -don’t think it’s not burning just because you don’t see it. Let the fuel completely burn away or use another can bottom to set over the stove to snuff it.
   To make a simmering cap -take another can bottom, 20mm high, and put a couple pencil size holes in the top of it. When the simmer cap is placed on your burning stove, the holes will allow the fire to continue to breathe without completely smothering it. Play around with different sized holes to customize the heat output to just keep a pot warm or simmer soup.
   You can simply secure some rocks around your mini stove to hold your pot, or fab a pot holder/wind shield from an aluminum coffee can like I have. A pot holder like this can also be filled with hot coals and double as its own little wood stove.

   Thanks to Zen for the info. Check out their site for additional stove designs and fuel options.

1 comment:

  1. Great info and I love the new colors, very easy to read now!


I welcome your feedback