Squeezbox Stove

[Andrew Dolman]

Have you guys seen this bloke's stove idea yet? It was posted on the British Outdoors Magic site yesterday. Looks pretty original, and effective, to me.

http://www.outdoorsmagic.com/news/article/mps/uan/5644

[ed hyatt]

The description is worth reading….and here is a picture to 'fire' the imagination….

The 37g stove and windshield

[Diplomatic Mike]

Quick link here.

[Tony Beasley]

Thanks Andrew, Ed and Mike,

I think it is a great idea and thanks for posting the links and pics.

When I can find some time I will make one and test it against the CC. My thoughts are that it will be just as efficient and easier to pack.

Tony

[Kevin Beeden]

Thanks to Andrew, Ed, Mike and Tony for propagating my Squeezebox Stove idea to BPL.

I was hoping it might prove to be more popular, but it seems to have fallen on barren ground…

I've created a thread at OutdoorsMagic to support improvements and refinements that I come up with.

[Kevin Beeden]

I forgot to say, my SqueezeBox Stove won Alpkit's coLAB09 design competition earlier this year.

Alpkit announcement
OutdoorsMagic news

Before you ask, no, this doesn't mean that it's going into production any time soon…

You can have a template for a MYOG version, though. Send me an email and I'll send the template.

[Tim Marshall]

has anyone made this from TI to burn wood yet?

-Tim

[Kevin Beeden]

No, but I'm tempted by the TiGoat foil to make a more robust SBS for a meths burner.

I don't think many people have even tried the Al foil SBS; I've sent out a few templates, but only heard two reports of actual builds… The response has been a little disappointing; the guys posted this thread, and Mark Verber added a link on his website, but it didn't seem to raise much more than a ripple. You never can tell what will attract people's attention.

For burning wood, I guess you'd need an inner burner chamber, although you could just make a little pile of broken sticks in the middle…

I think it would have to be taller than for use with a red bull meths burner (I use 32mm high burner and 24mm flame gap); that doesn't give much room for wood, compared with things like the BushBuddy, which seem to use an inner can at least 120mm tall.

I think, for a wood stove, you may be better off sticking to a 'conventional' double-wall burner base, and maybe use a folded windshield around the pot (to maintain a fixed gap between pan & windshield). Since those folded sections add weight over a simpler circular plan, it's only sensible to use them when they're supporting a pot above a non-supporting burner. And, if you don't need the double-folded sections to support the pan, it's much, much easier to make; those double folds are tedious to form.

[Tim Marshall]

much effort has been put in to prove that a double wall burner is no better than a single wall for wood.

Could a 3rd section be added to create the space needed under the pot for the fire?

I think this stove is cool. I think it would be hard to build vs a standard pot stand and wind screen. But for wood i may consider it as it will shield the flame well and hold the heat tight to the pot. Hmm..

I'd love a template to play with.

-Tim

[Steven Evans]

Tim, I built a "sort of" same concept Ti wood burner earlier this year. It's nowhere near as nice as Kevin's but it burns wood and packs inside the pot…easy to make and you could DEFINITELY improve on my version. Mine was sized for the 550 pot which I found to be a bit small for a wood stove. Tough to keep the flame up and going.

Oh, and single wall because honestly I don't really see a difference.

I don't have any pictures handy, but here a link to the one on my website.

http://www.suluk46.com/images/R%20and%20D%203%20-%20Ti%20Wood%20Stove.jpg

or click here

It's tough to see in the picture, but the floor of the stove slides into grooves that I cut in the bent pot body. That way you can disassemble it and place the floor in the bottom of the pot with the stove body on top…because it's collapsible, it all fits!

Kevin, awesome stove by the way.

[Dan Yeruski]

The not so good points outweigh the good.

Not so Good:

-Foil is thin, so vunerable to damage.

-Being lightweight it might blow away.

-Takes a bit of practice to mate the lower and upper sections.

-Whilst there is some leeway in the diameter, it's best targeted at a specific pan, so you need one for each pan design.

-It works best with handle free, or shallow handle pans.

-It works best with sharp radiused pans. Round bottom pans may slip off supports.

Good Points:

+Combines pan support and windsheild

+Lightweight

+Compact, fitting inside the pan it supports.

+Can be picked up and moves with pan in place.

+Can be made with simple tools.

I seems there is twice the amount of material required for a Squeezbox as required for a Caldera. What are your calculations on that?

[Kevin Beeden]

> Could a 3rd section be added to create the space needed under the pot for the fire?

The upper section relies on the double-folded lower section to support it, and, since the upper section isn't supporting the pan, it doesn't load the lower section much. If a 3rd section was added below, it would have to support the pan (if I understand what you're asking), and would have to have the double folds, and I'd start to worry about the two pieces 'cheesewiring' through each other, although edges can be reinforced by folding.

But yes, you could devise a third, lower section.

[Kevin Beeden]

Dan,

I'll reply on Monday; being thrown out of the building now…

[Tim Marshall]

steven,

i like yours but i think the reason you're having trouble keeping the fire lite is the short height. I have played with many cans stoves and how high the pot is from the fuel makes a big difference in how well the fuel will burn. I think if i did it it would be 2 sections and the top section would hold the pot from the pot lip.

Could you make the accordion style bottom unit with a cylindrical top unit that fit down into notches in the lower unit?

-Tim

[Steven Evans]

Could you make the accordion style bottom unit with a cylindrical top unit that fit down into notches in the lower unit?

Very possible. I plan on playing around a bit in the future and I like the way the accordian style is capable of packing into a pot smaller then itself. While I don't think a double wall is much more efficient, I do think there is some benefit to having a grate as the floor, much like the bushbuddy. I think it burns alot nicer that way – maybe air can get to it a bit easier?

[Rog Tallbloke]

Congrats to Kevin on the award, it's a neat design, and light for a support/shield design too.

Re single wall versus double wall; double walls insulate the firebox from heat robbing wind and keep the stove running more evenly across a variety of conditions. That said, a single wall stove with a 3/4 circle shield surrounding both it and the pan is just as good, and simpler to make.

I made this prototype to take to Sardinia, where there are strong sea breezes at the end of April. Accordingly, I kept air holes to a minimum, just a feeding hole on the upper section, and a replaceable chicken wire grate. This worked well in the wind.

.

.

It ran a bit smokey when the wind dropped though, so I had to supply the 'wind' by blowing through the feeding hole until the added fuel got going. A set of small upper holes with a collar to slide over them to vary the amount of air intake is part of my next design, which will be made using 0.005 Ti foil.

By the way, I found the sand stuck to the woodtar on the base of the pan slowed down the flamefront when using an alcohol stove, improving efficiency a bit. A cheaper and lighter option than a jetboil pan. It stopped the pan sliding around on the supports too :-)

[Mark McLauchlin]

I know what my next project is! I have an MSR titan kettle

[Kevin Beeden]

Okay, here are the answers to Dan's questions.

First, I'd suggest reading the article about the SBS on OM; use the link provided by the OP; it explains the rationale and development of the design, and I think it's a pretty fair assessment of the design, and includes pros and cons at the end.

The SBS is certainly heavier than an equivalent Caldera Cone,and your guess of twice the material is about spot on. My Clone generator reports an area of 61416mm2 for a Titan kettle. This corresponds to 24.5g in 0.15mm Al foil. The equivalent SBS has an area of 2*12.5*60*(78+10)=132000mm2, corresponding to 53.5g in 0.15mm foil.

But the SBS was intended to overcome the storage problem of the Caldera; it will fit into the pot it supports. My home-made PET bottle caddy weighs 31g, bringing to total weight to 55.5g, so it's a toss-up which is lighter.

My measured values for Clone and SBS are 25g and 45g respectively.

When it comes to manufacturing, I fairly soon abandoned any plans to go commercial, which is why I'm offering the design on a MYOG thread. The amount of material used isn't straightforward (because the Clone isn't straight…). The SBS is made from a simple rectangular strip, so can have optimal use of the raw material. The Clone has curved edges, and so there is waste material between Clones. As a worst case, the xExtent and yExtent values for a Clone are 205 by 591mm, giving an area of 121155mm2 (cf 132000mm2 for the SBS). Of course, savings could be made by sensible tesselation of the patterns.

Now for the issue of stability. The SBS is contructed from a lot of triangular folds. They form triangular columns that are very robust, and very stable. For instance, take a look at the little 6g potstand in the OM article; that will support at least 3.6kg (that's when I stopped pressing; I didn't want to crush it). The sides don't bow out; that's part of the attraction of using folding to make a windshield (how the SBS came about). All those folds add great rigidity and strength, where a simple windshield would just flop about and fall over.

With sharp radius pots, such as the Titan kettle, the pot sits quite stably in the SBS, and you can happily rattle it about; I spent three days on the Alpkit coLAB stand demonstrating this to people.

Larger radius pots don't sit as well, as there's less of the fold to support them, so they're not suitable for use with the SBS. But then, not all pans are suitable for use with the Caldera.

The Caldera Cone is brilliant, which is why I Cloned it, (and later added the Flissure variant) and I'm not going to say that the SBS is better; it's just a different solution to the same problem, with different pros and cons. Everything involves some compromise, and the SBS compromises marginally on weight, whilst having a little more versatility over the pots that a particular SBS can be used with.

One other valid objection to the SBS is that it occupies the pan, and a lot of people like to store stuff in the pan; I can get the SBS, a burner and a lighter in the Titan, with a little room left to store small items. I know a lot of people put a little fuel bottle in the pot, but I prefer to keep methanol and Bitrex out of my cook pot.

[Kevin Beeden]

Just seen that Dan has edited his post in a fairly major way…

I see that the list of pros and cons is taken straight from my description in the OM article. Fairly objective assessment, I think?

Taking the first five cons:

-Foil is thin, so vunerable to damage.
-Being lightweight it might blow away.
-Takes a bit of practice to mate the lower and upper sections.
-Whilst there is some leeway in the diameter, it's best targeted at a specific pan, so you need one for each pan design.
-It works best with handle free, or shallow handle pans.

Four out of five are equally applicable to the Caldera Cone, and the Cone takes a bit of care to ensure the pan is seated properly.

As for the blow-away stove, maybe we need to adapt the 'light, cheap, strong' maxim again:

'light, cheap, won't blow away: pick any two…'

Maybe I need to add three of those 2g Ti tent pegs to hold the thing down. Of course, once you've got the pan on it, it's pretty secure, although the upper section could be blown away.

[Kevin Beeden]

> A set of small upper holes with a collar to slide over them to vary the amount of air intake is part of my next design,

Roger, wouldn't variable air intakes at the base of the stove be a better bet? That's how fireplaces have traditionally been 'banked' to turn them down.

We had a bit of a brainstorming session on OM, and R_Mac was kind enough to try one of my ideas out for me…

Trying to Make a Wood Stove

The idea was to investigate the effect of splitting primary and secondary air flows, purely as an experimental vehicle.

As for the relative merits of single and double walled burners, I can't comment; still haven't made a wood stove…

However, that's pretty immaterial to my main point, which was that whatever wood burner is underneath and supporting the pan, it's usually fairly wind resistant (the ones I've seen are anyway; just a few holes drilled in the base). So the only bit you need to protect from wind is the flame ports at the top, to stop the flame being blown about, and to keep it close to the pan. So you don't need the Squeezebox's double folded lower section (and the associated extra weight), as it's not supporting the pan. Some shallow folding can be useful to make a simpler windshield more stable (as explained above).

Steve's concertina Ti wood stove looks good, and is at the same level of evolution as the concertina windshield that started the Squeezebox. I look forward to seeing how it evolves…

Finally. Roger, I did wonder what the hell you'd done to that pot. It was a relief to find that it was just sand…

[Rog Tallbloke]

> wouldn't variable air intakes at the base of the stove be a better bet? That's how fireplaces have traditionally been 'banked' to turn them down.

Hi Kevin, What you say is correct, not just for trad open fires bu the better designed woodburners like the scandinavian Morso and Jotel. However, what I'm after is minimal smoke, the rate of output is a secondary consideration, easily handled by varying the quantity of wood being added through the feeding hole.

What I've found is the flame gets blown about more if the stove has to work in the wind, when it has been designed to draw enough air for complete combustion in calm conditions.

Holes higher up the stove bring in 'secondary airflow' to aid combustion, but too many make the flame pattern erratic as soon as the wind blows, hence my idea to make that the area to adjust.

[Kevin Beeden]

Ah, I see what you're after. I'd thought of extending the testbed stove to add variable inlets for primary and secondary air; an obvious extension of the idea.

Hours of endless fun with testing regimes…

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