Nov 242011
 
Wood Gas Camp Stove - G4

Wood Gas Camp Stove - G4

Yet another tin can wood stove, I know, I know.  Still, I’ve discovered a few things that may make your next stove build a little easier.  What follows below are my trials and tribulations at build a really good working camp stove.  Note, I’m still experimenting with certain aspects of the design.  Always more experimenting to do.

My inspiration came from an article in Make Magazine which described building a tin can wood gas camp stove.  Here is a link to the Make magazine article.  The Make article inspired me to build my own stove.  My primary goal was to be able to boil water (for instant coffee) while on Boy Scout camp-outs.  Oh I know, it would much easier to build an alcohol stove (much cleaner and all – and easier to build too).  However, there is something cool about being able to cook using wood.  Plus, wood is in endless supply while on Boy Scout camp-outs.  Will be nice to have a little stove heater on cold winter camp-out nights.  A stove heater that I don’t have to worry about in terms of running out of fuel!  Oh, I know what your thinking, “What about the battery for the muffin fan?  Won’t that go flat in a hurry?”  Well, using 2500 mA/hr batteries we’re looking at over 30 hours of run time.

Now for a few negative comments about wood gas camp stoves.  First, until the stove gets burning good, the stove can generate a LOT of smoke.  All of a sudden, the stove will flash over and start burning wood gas.  The smoke produced goes to near zero at that point.  However, any pot placed over the fire coming off the stove is going to get really sooty.  Even with no smoke coming off the stove, the stove produces a real nice camp smell.  Now, I like the smell, however, my wife requires me to take a shower after experimenting with my stoves.  Second, my current design isn’t really something I would take on a hiking trip.  It’s too heavy, too dirty, and requires a battery.  Mostly, it’s just to damn dirty – the soot is a pain.  Lastly, the wood going into the stove must be cut up into small chunks.  In other words, the wood going in should be in cut up into pellets from small branches.

I don’t mean to be too negative.  I just wanted to get that out of the way first.  On the positive side, I really like burning my latest design.  A really small amount of wood produces a lot of cooking heat!  It’s amazing how little wood is required to boil 8oz. of water.  I’m hoping to quantify this more in the future.

 

Tin Can Wood Gas Stove Examples

Tin Can Wood Gas Stove Examples

This picture shows the four generations of wood stoves I went through until I ended on the final design (right most stove in the picture above – the Gen. 4).

Gen. 4

I could drone on and on about stoves 1 through 3 but I’m guessing you really just want to know about the final results.  However, a couple of things of note are worth pointing out from my experiences with stoves 1 through 4.

  1. A natural draft style stove stinks – literally.  In my opinion, these stoves require a muffin fan to blow air through the stove.  A natural draft stove, while simple to build and operate, is not near as much fun to burn as a stove with a muffin fan.  The speed of the muffin fan can be adjusted to give a “just right” amount of air movement through the stove.  A stove with a muffin fan is going to be much quicker in terms of getting your water to boil.  Plus, your not gonna have to stand on your head to blow air through the stove.
  2. Radiant heat from the inside fire box tin can may be an issue.  On Gen. 2 I simply screwed a muffin fan to the side of the outside tin can.  To fill the gaps I used a bit of “Shape Lock”.  Needless to say that setup didn’t even last one burn test!  The shape lock melted and the muffin fan got torched by radiate heat.
  3. Soldering pieces of tin together won’t work on a stove!  I learned this the hard way on my third generation stove.  The temperatures inside the stove can easily climb well above the melting point of solder.  When the stove is burning full tilt, the solder will melt and run out of the joints that it’s suppose to be holding together.  Not good!  The only solution that I have found is to braze the tin together.
  4. Radiant heat from the inside fire box tin can may be an issue (did I mention that already?).  That inside tin can gets really really hot!  As an example, I had my Gen. 4 stove going full tilt recently on my front patio.  The stove was setting on an upside down clay dish.  The dish was one of those clay pottery dishes used to capture water leaking out of a potted plants.  Anyway, the radiant heat had heated the bottom of the stove so high that the clay dish suddenly broke into two pieces.  Pow!  I later measured the clay surface temperature using an infrared thermometer at over 350 degrees Fahrenheit!  See below for some pictures of my solution to this problem.
  5. Since soldering tin together won’t work, I thought I would try to Tig Weld the tin together.  I happen to have access to a Tig Welder at my local hacker space i3 (see i3detroit.com).  Oh, I practiced on a bunch of old tin cans first to make sure all was good.  And welding along the rolled over edge would work (kinda).  But, Tig Welding tin can material is beyond my crappy tig ability.  I managed to blow a bunch of holes in my beautifully crafted tin cans – makes me mad to think about it even now.
  6. Gotta learn to braze if your gonna play with these kind of stoves.  This was my first experience brazing metal together.  So, I bought a kit.  I ended up buying a kit called “Safety-Silv 45″ which cost me $35 bucks at AirGas!  Rip off, I now know.  Live and learn, I guess.

I suggest you click on an image below to open the slide-show.  There are additional comments along the bottom of many of the pictures that help explain what’s going on.

The end…

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