How to design and make a Rocket Stove Griddle


Friends! We are going to be using these gas
bottles to make a rocket stove barbecue. This is where the idea for this rocket stove
griddle barbecue came from. It was making a rocket stove from bean cans at a camp out.
That was really great but I wanted something a bit more epic in scale. I already had the
experience of making a rocket stove heater for the workshop which I talk all about in
this video and assess it five years into it’s life.
If you are interested in the principals and design of rocket stoves do check that out
in the link below (video description). That’s the background, but in this video we
are going to be making a rocket stove bbq griddle from this gas bottle. A great way
to mark up any cylindrical object for cutting is to use a flexible, flat, square sheet.
Line up the edges when you wrap it around and your’e all set.
That way I can slide it to where I want it. Which is… about there.
A bit of the old, black on black… So I haven’t seen any other rocket stoves
on-line whether cooking or heating that use quite such a large diameter tube for the main
body of the object, so this will be a bit of an experiment and I’m not sure if it’s
going to work but I am quite hopeful. Ok time for some cutting.
So, if you know a better way of cutting these old gas bottles I’m all ears, please do leave
a comment below. I am using 1mm thick slitting discs on the angle grinder. Obviously it is
important to make sure the gas bottle is empty of any gas before you start! Especially if
that gas was flammable. In this case it was just CO2 so it’s a little bit less crucial
as long as there is no pressure there I’m OK.
So the material making up the gas cylinders I have cut up in the past, the propane ones
I used to make the workshop stove, were all 3mm thick. This is actually 6mm thick steel.
It’s really quite impressive stuff. As far as I can tell from the spark pattern, and
it is normally just a guestimate, it IS mild steel.
You can see here how quickly the discs get used up., So I have read that the ideal size
for the fee chamber is approximately 2.5 times shorter than the main riser on rocket stoves.
So that’s the kind of dimensions I am going for.
So it turns out , this is quite a complicated cut – to get this pipe to line up exactly
with this one, we need to cut what’s called a ‘fish mouth’ or a ‘saddle cut’. And to do
that I have printed off from one of there on-line templates just a wraparound thing.
I was really surprised at how ell these on-line template things work, you just enter the diameter
of the pipe, the angle it’s meeting the other pipe, and so on, and it prints you out a nice
template thing. It makes it so simple: I’m just marking round,
using a Stanley knife to cut away, and then the mighty angle grinder to get stuck in there…
So with all this cutting I thought I’d experiment with this alligator saw thing and a metal
cutting blade, and it was woefully disappointing and didn’t really get anywhere.
With the gas bottles in the past I have had quite good luck using my jigsaw, which seems
kinda similar to the alligator saw, but that was no good. Now friends, when you watch these videos I
hope you appreciate how long it takes me to wiggle-jiggle things around and the thinking
time involved, and just how much gets cut out of these videos. In this case this was
really impressive! It was just straight out of the gate, the saddle worked perfectly.
So much so I actually just felt like I had to sit and think for a minute anyway, Let
me know in the comments, do you want to hear more musing or do you want more action. Ok this is good. So we are basically there
with this. So what I am going to do now is reach through there and mark the hole I need
to make in this one. There is definitely a technique to doing these
plunge holes with an angle grinder and making the edges smooth. And I think I have gotten
a little bit better but I’m not sure what the secret is really other than practice.
Tilting the blades slightly away from the cut will tend to round the edge or cut more
of a curve, but there is only so much you can do that really in 6mm thick steel. That’s
especially true when you are using thin 1mm slitting discs. I could have used another
one of those cool on-line templates to make the hole in the riser that this is fitting
to, but is seemed prudent just to use the shape that I had and draw round that. Which
is what I did. Of course, the edge of all this hole wants to be nice and smooth so that
sticks and whatever you feed in there is not going to snag up.
The gravity feeding element of these rocket stoves is one of the main benefits of them,
so that’s quite important. Quite a rusty bit! Rusting away in my hand… The cool thing about the power hacksaw is
that it means you can get on with something else while it’s cutting. In this case this
is some “freehand straight-line” cutting with the angle grinder. So this hole is quite multi-purpose, it provides
a good amount of air for combustion. It’s also where I start the fire from in the rocket
stove, and it is also where you can clean the ashes out.
My initial measuring-stroke-guessing wasn’t quite what it should be so I will definitely
need to cut this rusty bad boy down a bit so that we can reach in and the propane torch
will fit in there to light it up. My feeling is that a good blast from a MAPP gas or propane
plumbing style torch is THE way to light these rocket stoves because it gets to clean burning
temperatures much quicker which means you are not polluting with partly combusted gasses
and it’s a much more efficient burn. It’s not ideal but… a little bit of work
on that. A good number of these discs got small. Lets have an interlude to go through a small
bit of theory with the design of the rocket stove. So ideally you want the air flow of
all the combustion gasses to come in to be about equal to the flow of exhaust gasses
and that keeps a really efficient burn. So this is a 7 inch tube. (that’s a diameter
symbol). That’s approximately 38.5 inches squared
of area available for air to rush through. This one is the same – this is going to be
the gasses coming in to the combustion area here. The exhaust gasses going out here. We
want to unify this. So you might think yeah great same amount of air going is as going
out equals good. But this area is the fuel magazine, so when that’s loaded with lots
of sticks that available space for air to rush through is much reduced.
Lets say that approximately a quarter, or something like that. So if we say that’s 10
inches squared available there, we ant to come as close as possible to 38.5 inches of
available air for combustion to occur. Which is where this comes in. It’s coming here – it’s
at a slightly offset angle to try and create a vortex in the burn chamber which makes for
a more efficient burn. Anyway this is a four inch squared tube which means it’s 16 inch
squared available area, a little but less when you take into account the wall thickness,
but lets just say 16 for now. Which gives us 26, umm, so we still want to find quite
a bit of extra air coming in! Which is where this thing comes in – it is going to pre-heat
air, and then we will have, hopefully some air at the back as well. Right! Enough with the chit chat. Lets get
welding! This is how the table converts to welding table. Normally I’ve got that wooden
ply sheet on for woodworking assembly, and other misc. tasks. So I have spent a long
time wizzing off all the paint with a flap disc on the angle grinder. Like an inch round
all these welds before tacking it up. For these welds I am using the highest setting
on my MIG welder. Along with a high wire feet, and that’s to try and get really good penetration
and weld strength, It is easy to get welds that are pretty on
thick material using lower settings but they can be very superficial. Not melting the base
material enough to get a proper join. In fact for 6mm thick steel you do actually need quite
a powerful welder to really get a good joint. Following the tack welded assembly I am using
a fairly standard seam welding method where I am kinda going an inch at a time That helps
prevent excessive warpage, but also in this case, it stops the paint from melting off
and filling your life with fumes. I was actually a little bit weary of this
internal weld I would have to do, but it actually turned out really nicely – I was a little
bit surprised. Now looking down the tube – not really any
light coming in. and then external inspection: it all looks great.
It’s been a little bit tricky to get this, clamped on how I want it. So here we go. The idea is the air is going
to come in along here, round the outside getting nicely preheated against this edge, before
coming in here at a nice tangent angle. Well that was epic and ridiculous, don’t do
it that way! It’s just this snagging here. That’s the only
problem. It’s just so close up the top here. You know what I am doing with this barrel
over the riser anyway right? Well this method of getting it on, I really
do like. It makes a really tight joint and without having to weld the really thin material
of the barrel onto the super thick material of the riser, which would be very difficult.
The slight miscalculation down here where I am having to adjust it was, err, unfortunate,
because it is very much a one way process, this thing. It slides in one direction, but
if you try and shift the barrel in the other direction it totally grips on and is incredibly
strong, so you can actually lift the whole thing now using the handles on the barrel.
It is also a very tight fitting seal you dont need to weld with and doesn’t need to be super
super accurate when you are cutting it. I am now using some more of this channel material
to fabricate another pre-heated air inlet, this time it’s going to be very much for secondary
combustion. So it is going to be higher up the flue. The idea with this is that even
if all the oxygen is been used in the primary burn down in the main burn chamber there will
still be some supplied so the flame will continue on up. It’s taking shape. It’s become quite heavy! So I calculated how many 8mm holes I would
need to drill in the steel to equal the amount of air coming through that channel. It ended
up being way too many, so the holes ended up being the beginning and end of some slots
that I desperately tried to cut at a really like steep tangential angle. Again, vortex
forming! And then before putting that channel on I
think we can improve the pre-heating somewhat by getting some fins welded to the body there.
That’s just going to increase the contact the air has with the surface of the hot metal.
I continued with the upcycling theme and used odd bits and bobs, so it looked pretty awful,
but it’s all behind the air channel anyway. So it is really nice on experimental things
like this where your’e not 100% sure and it’s prototyping, to control the airflow is really
quite nice. Right now I’m just welding on some scrap steel,
just to stabilise the base a little bit. Ooop, and there goes the trip switch, which
does happen occasionally when I am welding at maximum amps.
Come on, it stands up, lets give this baby a try! Started going now. Back here we can see the
paint’s bubbling off. That’s it! That is the power unit!
Friend, if you made it this far I salute you ! There was some geeky details in there and
like me you are obviously rocket stove interested, so lets do connect in the comments below.
To turn this into the rocket stove griddle / BBQ that it just want’s to be you are going
to have to join me for the part two video, where I take some random household items and
upcycle them into a preposterously efficient barbeque griddle. Apart from that, check out
my adventures in stove top fan upcycling. Or my five year review of the experimental
rocket stove style workshop heater.

62 comments on “How to design and make a Rocket Stove Griddle”

  1. Lucas Richard Stephens says:

    Very inspiring thanks! I have some cast iron wood burning stoves I would like to try converting to rocket. The excessive heat they produce seem to shorten the life of the burner when compared to my kitchen stove which is now about 100 years old and still working. Maybe a disposable burn chamber, secondary to the old cast iron burn-chamber….

  2. Eye Toldyoosso says:

    Cool man…;-p

  3. Lionel Roger says:

    Super un bonjour de France !!!!!

  4. Lionel Roger says:

    Attention aux pieds !!!!!!

  5. Chris Bannister says:

    Epic safety boots pmsl 👌👍🏻

  6. Sam Saville says:

    Looking forward to the ROARING success of part 2, and more bbqs :)!

  7. fiskfarm says:

    My "Tube" is about 6.5" or 17cm SS and is water cooled. Been heating our home for 3 seasons now: https://youtu.be/vHeIegF3HSc

  8. fiskfarm says:

    Can you say PLAZMA CUTTER? Works slicker than snot on SS as well as steel. Not all that expensive anymore and I can't imagine having built our RMH house heater/boiler without it. For cutting that square tube I would have used my $60 14" cutoff saw. That would have taken about 20 seconds. Love that classic hacksaw but I retired mine (wonderful homebuilt I made from an old piston water pump years ago). The new cutoff saws are great. Just aim the sparks away from the wood pile lol.

  9. Laurent Painchaud says:

    I want that chainsaw mill sharpening video you promised

  10. Eril Bolverkr says:

    very nicely done mate. I've been experimenting with rocket stove for a couple of years now and got a build very similar to your own out of old pipes. The best result I got was when I drilled holes along the length of the chimney on two sides then welded up rectangular pieces to cover them, then seal the tops while leaving the bottom open. This way the preheated oxygen get to mix with wood gas as heat goes up the riser and creates tertiary burns in the inside of the riser. An idea I have is to connect the two air-risers to a ring of similarly enclosed space around the top perimeter of the riser with holes in it. With sufficient amount of wood gas, this should create very clean flame at the very top of the riser although I don't think this would do much to the amount of heat that goes out.

    Keep up the good work mate, lookin forward to see the next one.

  11. FloweringElbow says:

    Friends, I have written this up into a comprehensive instructable with words and pictures. If you're planning to make something like this and are interested in the details I suggest watching part 2 of this video and checking out the instructable.
    Part two of this rocket stove project: https://goo.gl/JrCvM6
    Step-by-step how-to write up of my LV Rocket Stove build. https://goo.gl/SorouB?

  12. Colin Fowler says:

    Can we get some boots on those feet, please.

  13. Николай МАКСИМОВ says:

    Печь для того,что бы обогревать улицу?. У меня есть подобная печь,но она обогревает гараж.И сделана не так!

  14. John Williams says:

    Get some boots on mate

  15. Алексей Алексо says:

    Мне кажется что печь неустойчиво стоит…того и гляди..свалится. Пусть автор посмотрит видео наших мастеров, изготавливающих печи из газовых баллонов б/у. Резать кислородный баллон болгаркой (как и газовый) не безопасно! Надо быть уверенным, что там ГАЗА ( кислорода) не осталось..А то еб_нет так, -мало не покажется!

  16. oldschool823 says:

    what welder should I use?

  17. Claudio Carrasco says:

    Super… buen video amigo y qué gran invento… Saludos de Temuco Chile 🇨🇱 😉 🖐️

  18. Jaye Davies says:

    Running some coolant on the blade will help with the cut and the life of your blade. A pressure pump sprayer for the garden will the same if the pump in the saw is broken

  19. Jaye Davies says:

    Love the work boots and the work clothing

  20. GL Bell says:

    Thank you for this video. You have proven some of my theories that I had about rocket stoves. You have explained some of the details I have been looking for as well. I am looking to build one for heat but I believe your design ideas boost the output of my build.

  21. Blake Campbell Productions says:

    How come the outside barrel without insulation.

  22. Gustavo Melendez says:

    No entendi tu idioma pero !!!!genial!!!!!!desde Venezuela

  23. Timothy Mason says:

    Use A Diamond Masonry Blade They cut rock and Metal . You can use them for Months.

  24. Sammy Ymmas says:

    No music. More dialogue pertaining to the build

  25. Sammy Ymmas says:

    Great video by the way

  26. Sammy Ymmas says:

    Haha. Safety shield? Check! Heavy duty gloves? Check! Sandals? Sandals?!!!!

  27. Sammy Ymmas says:

    Man I wish I had just one friend like you. Just one. I feel like I could conquer the world if I had a friend with common interests.

  28. WannaBFree says:

    Fantastic project! Looking forward to view part 2. New sub here, I love watching projects like this one. Great job!

  29. Felix Pfeiffer says:

    Please tell me how you calculate a stove.
    I would like to design a masonry heater but I just don't get the physics…
    Where did you find out about this stuff?

  30. kbrigsby61 says:

    welll…., since u asked; NOOOOO music!!! Reazonable commentary (limited explanationz) is more preferred. also — i, enjoyed your vid, on ths 'build'. thnx!
    ok; my bad. upon re-watching ths vid, i, believe tht u sed (asked about) " …more musing", where-in i, had thot tht u had asked viewers abt, …'music'. eithr way, my original response stil applies. thnx.

  31. Jose fco. Samperio says:

    verry nice job ur a pro and the tools u have to i make my oun with recycle material pipe oil cans any kind of metal and they work to just fine .

  32. skeets says:

    Heavy steel pipe, power tools, welding and flip flops… that's a recipe for a hospital visit

  33. Jose Luis Cordon says:

    muy bueno

  34. jaimejaime says:

    fun – great work – thanks.

  35. homayoun Shirazi says:

    Good designs are simple. Were your choices consistent with this axiom?

  36. homayoun Shirazi says:

    Do you think that removal of rust prior to the actual construction would be of some benefit? Skillfully done as far as putting together various gometries are concerned.
    I am less certain about the reasoning behind your selection of different forms.

  37. Francois Dastardly says:

    Nice safety shoes !

  38. moonbluebob says:

    Flip flops mate aye😂😂😂

  39. David Wenbert says:

    Great video, beautiful product, excellent design, well implemented. But: I'd sure as hell wear more sensible shoes when on the ground with torches, saws, grinders, etc. One slip and you could be hobbled for a month or more, and serious foot injuries can be nortoriously difficult to heal. Sandals belong no where around power tools or welding equipment at any time, anywhere, ever.

  40. valveman12 says:

    Love that old bandsaw. They don't make tools like that anymore.

  41. Ian Wirtz says:

    Just a quick point… Coming from a production welding background, I would like to say that you would easily be able to weld 6mm steel tubing with next no warping. Stainless steel or manganese warp like crazy though. You will have less issues with longer welds also because of the amount of tie-ins. I personally would have tried to do that saddle in 2 or 3 welds.

  42. Papa Jon says:

    Ideas and comments from someone in the States who claims no knowledge, much less expertise, of/in anything.1.  Action, I finds too much music distracting.  The sounds of cutting, filing, welding, and dropping things on the floor does not offend me in any way.  I spend a lot of time looking for whatever I had in my hand ten seconds before.2.  That power hacksaw may be useful in cutting those cylinders, or the alligator saw with a proper blade.3.  The alligator saw which is called a recipirocating saw or sawzall in the States, works much better if pushed securly onto the surface you're cutting.  I've found the 'Demolition' style of blades work the best and last the longest.4.  When you don't have a template for a fishmouth you can cut the Y'ing pipe at the necessary angle, hold it to the target pipe, using your soapstone/pencil outline the oval shape and cut it out.  The hole will be oversized but you have a welder.  There are also handbooks with all the measurements of common pipe sizes and inclusion angles.  But a template is really great if you have one, I did not know they were available online.5.  Amperage settings for structural welding of quarter inch pipe is about 200 amps @ 20-22v.  As you are not building a bridge or skyscraper you can probably set lower powered machines at Max amperage and Max wire speed (high wire speed raises machine amperage) or whatever the chart affixed to your mig welder recommends.6.  I really liked your accessory curved air guide.  It could probably be cut as well with the power hacksaw if you have a way to prevent cut through.  Additional airflow may be gained by another going out another side  of the base in required.7.  Airflow:  The velocity increases as it passes through a restriction, I do not know if that is Bernoulli or fluid dynamics (same thing?).8:  There should be no light visible when looking out at a welded seam, and no smoke jetting out.9.  Any of the weaving patterns will give you extra heat, penetration, and a better looking weld.10.  This is the first of your videos I have seen and I am quite impressed.  Keep up the good work!

  43. J L says:

    Silly Rabbit working on hippy sandals..

  44. James Peterson says:

    Weld frenzy!

  45. Mr Snoopy says:

    Pretty sick bro

  46. Sma 556 says:

    Great hacksaw.

  47. danthedewman1 says:

    all saftey wearing sandals,,,lol…awesome

  48. Prashant Nagarkatti says:

    Nice work brother.. God bless u

  49. josh thurston says:

    Lenox diamond blade are the best. Lil expensive but last forever and cut like butter.

  50. Quincy Berman says:

    With a few modifications, that looks like it could make a nice trash incinerator.

  51. Archie FalconStorm says:

    Great project. Came out very good, but PLEASE you got all but one protective gear on and you forgot your protective boots. I can see you not able to attend BGT or AGT telling jokes and ending up in a hospital with boosted toes.

  52. Paul Lee says:

    dude.. get some work shoes. watching your video makes me nervous

  53. Accel Well says:

    Nice shoes there chief

  54. MGTOW GHOST says:

    HOW VERTICALLY STABLE IS IT ???

  55. Moritz Baumeister says:

    @FloweringElbow

    where can I find these template generators at https://youtu.be/s_aKIs8sYPk?t=179

  56. minouche4924 says:

    Lunette, casque, gant, tong…

  57. James Martin says:

    Take a look at those frequency emitter's used in hydropnic system's to oxygenate the water. Alcohol or white gas with a frequency emitter in the tank that causes the fuel to vaporize and presurize the tank. Add in a presure sensor to kick the emitter on and off to keep a steady presure in the tank. Then run your fuel lines to three HHO 32 micro jet burners at the top of the rocket stove. Add in a pre heat dish under the the burners. Add in nintinol high output thermal electric generator's close to the top of the rocket stove to generate electricity to operate the emitter and you could alway's add in Wireless energy transfer technology to power LED lights set up to work off the Wireless system and or charge up a battery bank or all your electronics. Make a smaller version and set up a Wireless mini induction coil with a graphite rod suspended in the center to operate an a absorption refrigeration system off your wireless system. If y'all are going to make a rocket stove? Make one that gives you lots of options mate! 😎👍

  58. James Martin says:

    Other idea, make a large hand warmer that will run for at least 48 hours. Then design nintinol high output thermal electric generator's with Wireless energy transfer technology that you can attach to the top of the large hand warmer. Get a copper radiator and make a copper pancake resivor that you can slip your large hand warmer under with the copper radiator and pancake resivor filled with Gallium Aluminum Scandium alloy to absorb and conduct the heat. Set copper radiator onto it's side within insulated conduit to use drafting to heat the air. Use an absorption refrigeration system with the concept for air conditioning and refrigeration of goods. 😎👍

  59. Dave Kauffman says:

    Built a rocket stove with galvanized stove-pipe, no extra air-intakes, I had the thin steel glowing orange/red when I'd fill the J-tube with sticks and other wood.

  60. shadow138 _ says:

    Yes they work great on metal. Last alot longer. They are also alot saver to use less likely to shatter.

  61. Wilfrid Kolarik says:

    Very good ideas for burning, the top

  62. Henok Yohannes says:

    can u provide the cutting template designer website

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