I've lurked here for some time and got a lot of useful information, but decided to come out into the open to share a recent project that some here might appreciate.
I've been reading about the various gasification stove projects here and elsewhere with a lot of interest. I've got a larger wood gasification stove (a commercially produced Woodgas XL, which is about the size of a gallon can), and have been meaning to build a quart can stove of my own. In the back of my mind, though, I've continually thought there has to be a better way to do this....
- more compact than a quart can
- lightweight: 8 oz or less
- sturdier than a can stove, without having to fit parts together
- integrated bottom plate, to catch ash
I started keeping an eye out for a suitable vessel to use as the platform. Every time I saw a double-walled stainless thermos, I would look at it and try to imagine it being transformed into a stove. The problem is that they're all too tall, or have too narrow of a top. Poking around, I found a little stainless tumbler online:
It's made by Interdesign, and the model is the Forma 21860 tumbler. I found one for ten bucks at Target in the bathroom supplies section. It looked promising, but once I got my hands on it, it seemed really heavy (probably 10 ounces or more), which was a double problem -- too heavy to be worth the trouble, and hard to work with.
Then the other day I was at the Container Store, and they had the same tumbler on the shelf. I looked more closely, and realized that there are two slightly different versions of it -- they had both, all mixed up together. They look the same from the outside, but one is half the weight, and clearly made of lighter weight stainless steel. Visually, they're almost impossible to tell apart -- the lighter one has a slightly crisper angle to the top edge, and the bottom inside surface has rippled concentric circles (you can see this in the pics below), while the heavier version has a completely smooth bottom.
Unfortunately, I don't know which version is newer, or more likely to be in stock at retailers.
4.8 ounces, 3-7/8" high, and 3-1/8" at the widest. Score.
The clerk wrapped it carefully in tissue paper, telling me she'd hate for me to get home with a scratched up cup. Heh, heh.
This is a pretty crude homebrew mockup, but I think the design has real merit. I initially thought I would use an Irwin Unibit, which is good for cutting into sheet metal. That tended to skid around too much, and it was a hassle to get inside to work. So instead, I used a 5/32" titanium double-cut bit, which worked pretty well. The pimples around the outside are from popping through with the drill, and bumping the outer wall. A little unsightly, but so it goes. Obviously, this would have worked a lot better with a drill press and a better clamping system. Even so, it turned out ok.
I taped up the sides and top edge to keep from marring the steel too much, and went to town. I just used a small punch to give the drill bit some purchase, and then simply drilled out each spot with a cordless drill:
I did the same thing on the inside, making a number of ventilation holes on the bottom of the combustion chamber:
Then, a cleaning slot so that any ash that gets down through can be poured out:
enlarged with some very crude dremel work:
Add a piece of gutter screen to lift up the fire to get a bit better airflow:
So how did it turn out?