For the heck of it, I made a really light (but fuel efficient) cookset (just over 1oz) which can boil 2 cups reasonably efficiently. The hardest part was building it after drinking 50oz of beer. The pot is a tallboy can and most of the rest is a huge Asahi can. On the fragile side, but it works.

The details are here but the pictures capture the idea:

Edited by efredricksen on 08/09/2008 22:14:20 MDT.

Hey Eric,
Very interesting idea. My question is how do you take the inner can out without burning your fingers?

You can pick up the whole screen-pot assembly using a bandanna or something as a potholder and pour the water out of the pot. There's not much clearance between them so it works well. Some light wire or something as a bail might be worthwhile to add too.

I'd be interested to know your fuel usage and boil times.

My latest 2oz volcano kettle is doing 2 cups from 18C to boiling in eight and a half minutes with just under 1/2oz of fuel.

Interesting idea ! Could you put 2 tent stakes through the bottom holes to hold the pot ?

w.

I boiled 2 cups from 22°C in just under 9 minutes with no wind. Burn time was maybe another minute with 1/2 fl oz of Crown denatured alcohol from REI.

Note that it does boil over the sides a bit since the pot is so close to full, but that doesn't seem to cause any particular problem.

Edited by efredricksen on 08/12/2008 13:42:32 MDT.

You could use tent stakes (with some holes a little higher) but it wouldn't save you much, and probably would not keep the pot as well centered as the compression-fit support ring.

That's really good going for such a light setup.

I just built a new stove this afternoon for my volcano kettle. A bit heavy at just over an ounce, but it has better than halved the boil time. I boiled two cups from 17.6C in a couple of seconds under 4 minutes with 12g of fuel. As quick as a gas stove; Result!

Do you have details, Rog? Sounds pretty cool. I wasn't even aware of the volcano kettle concept. You must be using some beercan-heavy design to get it so light.

Yep, I make them out of beer cans and the judicious application of very small amounts of glue, but in such a way that the glue doesn't come into contact with the water or direct flame.

I have been quite successful with a 4g stove I make from lip balm tins, but the stove I made yesterday which got the amazing boil time is a 1oz heavyweight made from beer can ends with a double set of jet holes, one inside the chimney, one outside hitting the lower end of the kettle. Thanks go to Dan for the original 'ring of fire' idea.

Here's a pic of the kettle.



With the new stove I remove the bottom shroud with the air holes in from the kettle and sit it direct on the stove, which has air moving up the centre to feed the flame from the inner circle of jets.

Here's the new stove:



And here's the complete unit in action: Total weight including stove, kettle and priming pan is 2 3/4oz.



It's running with the top shroud off so I can get the turkey thermometer in. It lift the 2 cups at around 20C/min. I've done half a dozen tests now using water at 17.6C and 12g of fuel. I'm getting a consistent boil time of four and a half minutes including priming.

Edited by tallbloke on 08/13/2008 03:13:01 MDT.

Is that what you're going to send me? That is very cool. I can't wait to see it.

-Tim

That's pretty darned good. Your setup is getting 676 Watts into the water. That's about what I get with my high efficiency wood stove, but it weighs 14 oz. By comparison, typical Pepsi can stoves heating a pot do about half that so you've cut your fuel burden in half.

If you're using straight methanol you're getting 67% efficiency; straight ethanol 60%.

Either way, that's excellent. It would be nice to see a section drawing of your kettle stove. Clearly the key is to give the energy one way out: through the pot!

Tim: I don't have enough large US size beer cans to make more of the stoves, so you'll get the internal only 4g version, which is still efficient, just slower. If you send me a bunch of cans (a mix of heine's and fosters) over with the quilt I ordered from you I'll make one to include with your large kettle.

Herman: Yep, I'm really pleased to have hit 60% efficiency. I use british 'methylated spirits' which is around a 90/10 mix of ethanol and methyl alcohol. I'm also building a woodstove similar to yours from a sheet of 0.4mm Ti, it's a nice design. My problem will be that my cookset will be light, but bulky unless I can come up with a way to fold the windshield into the pan. Sure is nice to have that first cuppa within 5 mins of waking though, along with a woodstove to conserve alcohol. The kettle will also work on the woodstove for evening brews. :-)

I'm going through a patent application process for the design of the chimney inside the kettle, so no detailed drawings yet. Once I've got the pat pending I'll be selling a few of these kettles, so you can order one and then emulate it for personal use. If you can work out how the jointing is done. ;-)

Eric: Apologies for the thread hijack. :o)

Edited by tallbloke on 08/15/2008 02:38:18 MDT.

I look forward to seeing your 0.004" Ti wood stove.

Regarding storing the wind screen/chimney in the pot. I prefer to store the pot in the wind screen and the firebox inside the pot. The clearance between the screen and the pot is small so it wouldn't save much space to put it inside the pot.

By storing the pot inside the screen you'll gain a barrier between you and the soot.

Some other thoughts: The chimney acts as a pot support in my design. 0.004 Ti will probably necessitate some extra reinforcement or standoffs under the pot.

When assembled for cooking, the chimney is locked to the firebox by a bayonet style coupling. This makes it easier to move the stove should the wind shift.

Herman: I've replied on your woodstove thread so as not to clutter Eric's 1oz cookset thread further.

No problem with the hijack. I've been spurred by your setup to think about an internal-chimney beercan cookset, which I'll experiment with once I figure out how to cut nice circles out of the bottom of a can (without a lathe or drill press). (Advice?)

I just thought of away to avoid that requirement though, so maybe I'll try that first.

Once you think about water around the chimney, and then a chimney around the water, you start thinking it would be nice to have water around that chimney, and then another chimney around that water...

Lol, I know what you mean, but I discovered that the fancier the design, the more glue joints and potential failure points you introduce. Russian doll volcano kettle anyone?

For cutting circles to accurate sizes, you can buy a compass tool with a surgical blade on one leg, but they're not really up to can top material. I use a variety of old bits and bobs I have lying around, but not stuff I can point you to on the net. I have some ancient botswains drill bits and a set of cheap dremel bits which are handy. Otherwise, it's chain-drill, snips and half round file. Leatherman micra's are surprisingly useful. Patience is useful too. So is drinking the beer the night before you set to with sharp tools... ;-)

So I put together a kelly kettle type thing. I never would have thought it was a good idea but I was inspired by zelph's ring of fire which I wouldn't have thought was a good idea either.

The good news is it's pretty cute, weights 1.25oz and has a capacity of almost exactly 16oz. The bad news is it doesn't heat water.

I took a 24oz Heinekin can and drilled centered holes in top and bottom with a 2 1/16" hole saw. (I removed the top first for ease of assembly, though I glued it back on later.) Then I removed top & bottom from two V8 cans (right at the end, to leave a short taper at each end, on one can; tapered on one end for the other). I fit these two together and into each end (from inside) of the Heinekin can to create a chimney through the middle.

With an initial dry compression fit there we slight leaks so I used a very little silicone adhesive outside the V8 cans at each joint, which ended up sealing it nicely. (My theory is that the water will keep that glue cool enough (below 400°F), and hopefully it's safe toxicity-wise.) More good news - it was watertight.

I also cut a little V at the top of the can and glued on a spout - that's where cute comes in.

Then I filled it and stood it over a tealight stove and learned what some of you probably expected. The air comes in from the sides and keeps the flame right in the center of the chimney, and the water heated up only negligibly.

The key difference with the ring of fire is that there the fuel is in-between the pot and the O2, so the flame sticks to the pot. So I might have something if I had a stove with an open middle where the air could come up from below. I can imagine how such a stove would look, but how to make it remains TBD. (Not that I think any of this was a very good idea anyway.)

Edited by efredricksen on 08/16/2008 22:05:44 MDT.

Don't throw it away just yet. I'll bet things improve if you put some baffles in the chimney to make the flow turbulent. That will get hot gases in contact with the sides. You might also experiment with making the exit opening of the chimney smaller. Controlling the flow of gases in the chimney is an important part of stove efficiency. Too big an opening allows excess cooling air to be drawn up, too small and burning is inhibited.

Eric: Don't worry. It took me a while and a lot of beers to work out a good configuration. I just got my first order, so I'm not going to reveal the hard won secrets, as I'd like to have the market cornered for a little while at least :o)

Herman's advice is generally good. Have a think about gasflow, velocity, and exhaust heat.

If you want one of mine to steal some ideas from, get your hand in your pocket, but promise me you won't be going into production and taking my potential customers off me. :-)

How's this for cute? It's a one cup version made with a 330ml Heineken keg can. It weighs 1oz.



This uses the 4g penny stove and boils 1 cup from 17.5C in 4 mins 45 secs with 6g of fuel. Orders for this and the big 2 cup keg-kettle being taken now :-)

Edited by tallbloke on 08/18/2008 09:35:52 MDT.