mass catering

[jono]

some of those images are the green casting, some I took today. the reason the top half is black and the bottom half isnt is that it was sitting in perlite, though not enough obviously.the port looks more off center than it is because of the angle of photography. its fairly close really

[jono]

here, this photo makes it look good.;-)

[jono]

some critical refections:

A) I should have used dense refractory instead of insulative refractory for the first casting then backed it up with insulation. this stuff is too soft to withstand having twigs rammed in it, and so the sharp corners of the port are starting to degrade a bit already, though this could be a consequence of B.
B) I have learnt that you are not meant to mix refractory concrete to a wet and sloppy mix like normal concrete (as i did) and this may have been why it took so much work to purge the moisture from the casting, though it is also why i got away without having to build a vibrating table. I don't know what the consequence of this decision are for the mechanical or refractory properties of the casting.

future research goals:

I think a more important materials design challenge would be how to make this shape work out of dug clay and other readily available materials, as this research would be useful to the rural poor of the planet that are more likely to use this technology on a large (mainstream) scale because they don't have gas and electric cookers. This could also be a valuable contribution to "Instove" as their CNC lazer cut stainless steel combustion chamber could be omitted from their factory in a box outreach operation, thus making it more sustainable (environmentaly and logisticaly) and cheaper for their global south manufacturing partners to produce stoves. Also, if I understand peter correctly when he says that the oxygen reading from the stove was a bit on the high side, this combustion chamber could make the approvecho instove more efficient, by achieving near complete combustion with less air flow, thus reducing the dilution of the combustion gasses, increasing their temperature and so increasing the efficiency of the heat exchange surface.

[jono]

the begining of the tactical instove. I need to carry it on my back. Ill give it two detachable legs at the back, then use the front of a combustion chamber as the third leg. Unfortunately, my combustion chamber doesn't fit in the pan for transportation. cant decide if i will cut it in half and have some way to slot the riser on to the firebox, or make a different combustion chamber all together, or accept the design flaw. there is a lot of space between the pot and pot skirt. I'm trying to think of a way to use that space effectively without needing to add a chimney to the setup (which would make it substantially less tactical). sugestions always welcome

[peterberg]

Interesting. It looks like a 45 degree angled feed plus a riser fed through a narrow gate. As such, it looks like a small scale variant of the batch box concept with the port turned to a 45 degree angle instead of vertical. And also vaguely similar to a pocket rocket variant Erica Wisner built in Montana last October. I would like to do something with this idea during this winter months a soon as my firewood problems are solved.

[jono]

correct, except that the port is about 30 degrees off vertical. the goal is to make something that is taylored to the needs of a cooker. there is definitely room for improvement. I'll make a video of the burn when I get the chance to show you what i have learnt so far

[teo]

Hi jono, congratulations. Did no paint came off the barrel? the core/riser held in place only with this rod? How heavy is this setup? Thank you

[jono]

thanks teo. yes, that rod is all that holds the core in place, which works fine rattling around on a trailer when the stove is the right way up, but not when it is rattling around in the back of a van on its side.

Weight: That version is way heavier than it needs to be because the chimney is made of about 3mm wall thickness mild steel, because that is what the scrap man had, though it absolutely does not need it. temps are so gentle by that point you could definitely use lightweight flue liner, or if you want it to look posh, stainless steel fluepipe. I have no scales at all anywhere (I just looked) and I am often way out when I make these kind of guesses, but lets say that my large stove is obscenely heavy, like 40 kilos or something, but if you were weight conscious when you made it you can take of about as much metal from the barrel (by removing the top and bottom, which are a heavier gage steel than the sides)as you add with the chimney, and the core is about 2kg, so the whole thing could easily weigh between 10kg and 20kg. I cycled my trailer carrying all my ingredients, including about 70L/kg of water, so whatever your planning, you may need to factor in the weight of the food as the dominant factor.

No paint came off or charred internally and any noxious fumes off gassed by the internal paint were not visible in the chimney smoke. the barrel does not get very hot at all because the food in the pot saps so much heat from the fire, even without an internal pot skirt and with a fairly generous 50mm+ top gap. At its very hottest, you could not comfortably leave your hand on it for a long time, but it was no where near hot enough to burn anyone (ill guestimate 70c).

[mudder]

very cool and interesting stove works!

[docbb]

Dec 3, 2015 7:00:36 GMT -8 peterberg said:

Interesting. It looks like a 45 degree angled feed plus a riser fed through a narrow gate. As such, it looks like a small scale variant of the batch box concept with the port turned to a 45 degree angle instead of vertical. And also vaguely similar to a pocket rocket variant Erica Wisner built in Montana last October. I would like to do something with this idea during this winter months a soon as my firewood problems are solved.

do you mean this one?

[peterberg]

Yes. I brought in some ideas when she built this one. It burned clean in less than a minute and it started up very quickly. Holds a lot of promise but unsure about its significance in the long term.

[nixsee]

jono , if you're still around, are your pictures of this build posted anywhere online? They've all disappeared from the forum and I'm very interested in seeing them!