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Post by satamax on Feb 8, 2016 10:17:26 GMT -8
Davisdesigns, you could encase firebricks with metal. That's no casting. And it works. Just as an example www.permies.com/t/35569/rocket-stoves/Range-retrofit I hold parts with wire, You could do the same with firebricks too. You could extremely carefully drill them on the edges to pass wire, which you would insert into two holes in the exterior metal, and tighten to hold them. For your "barrel" or "bell"; don't know where you found the term capacitor. You could also find "home heating fuel tanks" or "Tractor fuel tanks"; Like i have used in this build. donkey32.proboards.com/thread/1817/starting-build-220mm-rocket-double You don't necessarily need round tanks. I also have a nice 50cmx50cmx145cm stainless tank in stock for a future build. Or if you have a brake (bender? ) you could do "pinch rolling" where you do tiny bends every half inch or so. So that makes yoursheet metal go round.
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morticcio
Full Member
"The problem with internet quotes is that you can't always depend on their accuracy" - Aristotle
Posts: 371
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Post by morticcio on Feb 9, 2016 0:29:24 GMT -8
Contacted people on youtube that have videos of all steel construction, the consensus was they dont last long and the ones that do, are not real 'rocket stoves' reaching 'incinerator' temperatures. Isn't that exactly what you were told on here?
For what its worth, I would do a first build with firebricks and clay slip before jumping straight in the deep end with refractory castable.
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Post by peterberg on Feb 9, 2016 3:15:36 GMT -8
Contacted people on youtube that have videos of all steel construction, And YouTube is known as a source of very trustworthy testimonies, much more reliable than rocket stove specialist forums, oh yeahh...
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time
New Member
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Post by time on Feb 27, 2016 15:15:49 GMT -8
I'm Not sure how i haven't found this thread previously. However i have some points to add, to confirm max's experiences.
I have a 6in All metal batch rocket with S Portal. The Riser is insulated with 100mm of fire blanket. The riser is 10mm high pressure pipe. the batch box is lined with refractory brick (since it started to be eaten away).
after 6months of use the 10mm riser thickness is down to 4.7mm in some of the areas i can reach with the ultrasound probe.
It chews through 5mm stainless steel rod that i use as a rack in the bottom of the batch every 5-6 burns.
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Post by ericaus on May 22, 2016 14:09:54 GMT -8
""I'd like 24" diameter but not finding tanks available in that size and i do not have a sheet metal roller.""
davidesigns you may consider looking for suitable pipe section. 600mm is quite a common size and you may be lucky enough to pick up the correct length at scrap price. If you're handy with fabrication, you can make up the ends and cut the appropriate openings. Good luck. Eric
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eng
New Member
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Post by eng on Jun 1, 2016 0:35:40 GMT -8
Peter and other Senior members, I admire your patience. I am surprised that the discussion about using steel fabrication is dragging on for as long as it has. During my apprenticeship I worked in a foundry each Wednesday helping the foundry-men do the weekly cast of iron. Coke was used in a cupola furnace to provide the heat. (Before coke wood in the form of charcoal was used in the old days).The iron melted at 1100 C. A well designed wood burner will reach at least 1200 C. Mild steel is made from pig iron which is a rough cast iron. A steel furnace reaches 1700 C to burn out the carbon, mild steel melts at 1527 C.Cast iron is more long lasting in a burner than mild steel but it burns out after nine to twelve months in a furnace where it is not cooled by air or water. All this is to back up wiser people than me when they say DO NOT build a serious wood burner out of mild steel. It is wasteful and self defeating. Be aware of the time that Peter and his friends have put into this project they have done awesome work and have been free with their successes and their failures. I have built several burners over a forty year period and they have not reached level of sophistication that Peter and others have shown in this forum. If anybody wants to do better than the successful burners shown in this forum, do your home work,experiment, and let us have your results, but remember that some very clever people have been trading this path before you and be humble.
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Post by satamax on Jun 2, 2016 0:21:55 GMT -8
Thanks a lot Eng.
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Post by ringoism on Aug 3, 2017 9:45:12 GMT -8
The flame temperature of a properly build rocket stove may exceed 1200°C, but this does not mean that any material touched by the flames could actually reach the flame temperature. The industry uses stainles steel for similar conditions since quite some time. Some stainles steel is rated for up to 1150°C under corrosive conditions, but this kind of steel is very expensive. If one is willing to spend quite some money and lots of time for careful selection of material and design, one may be able to build a durable and high performing metall rocket stove. I never did post re: the ultimate product of my own questions about an all-metal rocket, posted somewhere here about five years ago. Prototype is there @ "successful 3-1/2" portable rocket" or something. That used MS, lined with low-grade SS atop the burn tunnel, and tile/s.wool-lined on the tunnel sides. Riser was a thin magnetic grade SS (404?) wrapped with Superwool and some heavy window-screening. The atmosphere seems to be a lot of the trouble. Tunnel sides held up reasonably well so long as I kept the tiles fitted and in good shape. Final season (2-1/2 winters total) tiles cracked enough that I gave up / got ride of them, at which point the warpage/scaling seriously accelerated. Tunnel top is MUCH hotter, and eventually burned through the thin, low-grade stainless as well as the MS. I had clay-clad ceramic wool over the whole thing, so it still ran fine and I didn't realize the damage till I disassembled it. Riser was badly scaled on the lower half, but it still had plenty of structural strength to support itself, and I'll probably throw it in another build as-is and keep using it just to see how far it'll go. Anyway, re: the "production" version: Will post pics if I get the time. Anyway, made with a hand-made 33" brake, and "all metal" but only the bell is mild steel, and the burn area is lined with insulating firebrick / ceramic wool. Base of the stove is polished 202SS which looks nice and it isn't exposed to high heat. Feed magazine (this is a capped "J") is thin 304SS which discolored / warped on the lowest inch or so (where it glows red/orange at full burn) but no actual damage yet. I used a bit thicker 304 for the ash tray, which doubles as the LOWER half of the burn tunnel. It's still only 1mm so warped quite a lot and shows corrosion, but no scaling. I figure it could do a couple seasons of nightly use, and it's cheap/easy to replace. Tunnel top is where everything is harshest, so I've got 310SS in a little piece up there, which kind of directs secondary air from my P-channel-ish thingy, and also forms something like a trip-wire further ahead, and also provides a little extra support to the potentially more brittle ceramic fiber board that actually forms the tunnel top and supports the riser. This 310-grade (1150C rated, and these ratings usually give a little leeway) shows no degradation whatsoever after a season, and yes, I get temps high enough to make the ceramics in the core glow bright orange. And yes it's expensive at 3x the price of "normal" stainless, which is several times the price of MS. Total cost of the stoves still well under $100, though (labor not included, of course - 2-3 days' worth each!). Of course, most materials probably cheaper here in India. I got about a dozen of these built / out there running over the winter - people who've been using them seem happy, and the nice thing is that the stove is lightweight enough that it can be pretty readily removed / stored away in the off-season. I think if I had thin 310 in the riser / 1.5mm in the ash tray (I made two units this way), I'd have something that wouldn't really need attention for easily 3-4 years. Firebricks / tiles are cheap and fairly easy to replace (in my design) if they fail eventually. The metal just sort of holds everything together, and in areas where it is directly exposed, either a high temp specialty grade is used or the low-complexity pieces are made to be easily replaced. time will tell, but it seems to be working out well. -Eric
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Post by drooster on Aug 4, 2017 12:35:26 GMT -8
That's a good detailed description but a picture is worth a thousand words.
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Post by satamax on Aug 4, 2017 22:29:27 GMT -8
There is a guy, on the rocket mass heater page at facebook. Who claims his steel Heather has nothing to worry about after two Winters. When you see the heat riser, and the soot in there. You know he's another one who has no fecking clue about what a rocket is! This gets me mad!
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Post by drooster on Aug 6, 2017 11:52:25 GMT -8
There is a guy, on the rocket mass heater page at facebook. Who claims his steel Heather has nothing to worry about after two Winters. When you see the heat riser, and the soot in there. You know he's another one who has no fecking clue about what a rocket is! This gets me mad! Well, Faceb@@k does encourage a whole 'nuther class of contributors It's all about giving your stoves girls' names innit.
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Post by satamax on Aug 7, 2017 0:55:46 GMT -8
Well, i'm nit registered there. Otherwise, i'd go barmy!
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Post by coisinger on Aug 7, 2017 3:57:43 GMT -8
Still haven't built my first.
Based on what I've read here, elsewhere and the hundreds of hours of video I have watched related to batch rockets and other variants, I will be constructing with firebrick, insulating brick and considering any parts that are metal consumables.
My wife says I have grand plans for everything and I do, but my time to realize them is limited, thus I sit and sketch and refine and prepare for one heck of a stove 'one day'.
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Post by ringoism on Aug 11, 2017 0:49:39 GMT -8
There is a guy, on the rocket mass heater page at facebook. Who claims his steel Heather has nothing to worry about after two Winters. When you see the heat riser, and the soot in there. You know he's another one who has no fecking clue about what a rocket is! This gets me mad! I don't doubt it, Max, and I can understand getting mad about pseudo-rockets... But in my case my riser is squeaky-clean after three seasons using all sorts of wood (incl. mixes of some a bit wet/green)... and almost never any visible smoke out the pipe either. And bright-orange-hot refractories down in there as I said... in short, it's definitely a rocket. And 310ss, for sure, is doing the job (at around $10/kg here in India - pricier than 50-cent insulating firebricks, but okay in limited amounts for those highly critical areas). RE PHOTOS: trying to upload some of my stove in operation, and of some charts of SS specs, but getting the same message I have been for a year or more: "This forum has exceeded its storage limit..." Files are sub-200kb. Can anyone tell me how I ought to be posting photos here?RE: other SS grades for anyone interested to research, there's 442, 446, Sandvik 253MA, and others, some of which are supposed to be "far superior" to even 310, which is good to around 1100C. There's definitely scope here. Another useful article besides what's been mentioned above: www.bssa.org.uk/cms/File/StainlessSteels_at_HighTemperatures_EN.pdfThanks, -Eric
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Post by satamax on Aug 11, 2017 2:54:28 GMT -8
To post photos, i like hostingpics.
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