Enjoy the vids! A few friendly pointers from an old retired building guy: Dryer mix, stronger concrete, Rebar or wire mesh (fencing) for reenforcement, 28 day cure is an industry standard. Smallish fires early on, then gradually hotter later. Excellent DIY.. Great job man!
I love hearing tips from those who know these materials from long experience. I’m definitely listening. I’ll be doing another refined build, incorporating a lot of the feedback and suggestions that have come via the comments. But, I may call it the “Parnell method” given that you’ve summed it up so nicely. Thanks for the feedback and encouraging words.
I have talked about building one of these to supplement a backyard fire ring for my father. As an almost-retired concrete guy, he agrees with the mix looks a bit too wet to start off. A wire mesh might be best for a small project like this, centered around the middle of the cylinder inside concrete, especially when you have heating/cooling like this. He was concerned for the long term of the project with rebar sticking out the top rusting out and moisture getting into the top, recommended just setting pan/pot on top of small ceramic tiles of some sort. Also, might have some expansion cracking problems with the rebar if these standoffs heat up quicker than surrounding concrete often, and looks like this might happen with quick heat transfer path from fire to pot to standoffs. Also, I see comments already about using the more specialized high heat furnace concrete instead of the standard concrete with perlite mix and go easy on the initial fires to help avoid cracking. A great design we will use without much modification though, and I'm sure your design has evolved in the past few months. A good combo of simple and effective to supplement a fire ring for doing some of the initial cooking using just small backyard wood. edit: Yep, looks like some more video content with evolved design. Good stuff.
@@Jaden48108 Kaowool is a blanket of flexable cermaic insulation that is like 99.99% refractive to heat. fireplace supplies have it but it is available on amazon as well. www.amazon.com/s/ref=nb_sb_noss_2?url=search-alias%3Daps&field-keywords=kaowool I made a smelter and a fordge out of it recently
You are the Pioneer of this project for me. I have simulated this with scraps and concrete. Using an entire 80lbs bag of crack-resistant concrete with a small $4 bag of Perlite in a 7gallon bucket curing right now. I ran out of material and in fact, the concrete settled full 1.5" for the top after tapping the sides for 30+minutes. The perlite has a lot of air to persuade out to the top... The armature was made of an unsellable refused stainless steel mesh filter from work. I used the Stainless steel expanded mesh metal sheet, rolled it into a double-layered cylinder and wired together. I made 4 cuts from one end through both layers to preserve the round while folding it over for the opening space. Then I cut a 4" refused papertube just taller than the bucket and used the cut-off for the opening molding. Strategically, I used stainless steel cuttings from cloth hangers to suspend the mesh cage around the tube and opening. I know, long story but, there's a lot... Last night, I dumped concrete mix inside the mesh against the tube because you will need to, it doesn't flow through. Made me believe the core could be slighty different Perlite mixtured ratios for the experienced; I am not experienced just an observation... So now my opening is 1.5" short because I was out of concrete and it settled deeper than anticipated. Today, I purchased Mortar cement and another small bag of Perlite. I made a mold with an old plastic oil pan using your cardboard+tape method on everything. Finally, mixing 10 scoops of Perlite and 2 scoops of mortar cement to perfection I made an additional Stand for the "wind channel" instead of bricks. I really needed to tap it with a hammer handle vertically to get the cream to surface because the Perlite kept packing down more and more with all the abstract edges. Last thought, I'm really hoping the "C" shape Stand of insulated concrete will controll expansion separately from the tower. I made a fire-brick puck of the remaining mix in a cup for a test sample under a torch. I hope the simple rolled steel mesh cylinder with extra folded layers over the opening with keep the stone together. I apologize for the long story I hope it helps anybody else who was anxious to try this project. So, $23 in total.... I'm anxiously waiting a month from now before I burn anything substantial or ripping hot. If this works out all credit goes to you for the Inception, and if I failed, it will completely be on me lol. It's almost backyard season here ugh.... THANKS AGAIN!
Hi Derber. Your rocket stove project sounds like it is coming together nicely. This comment got stuck in the "possible spam" folder. Thus my not responding until a couple days later. I had to find it. Let me know it turns out. Especially the torch test.
Ireland: love your thinking behind your project, problem solving all the time. That is what life is all about. Find the need, try to solve it, never be afraid to fail as you have just eliminated one problem. Go again and have pride in what you finish. I love what you have finished and hope you much success, god bless
@@domingue4god He has no problems! He is making good money off of every ones comments and suggestions. A few epic fails fuels his helpers to keep commenting. Good job dude! I hope you get rich!
This is great! I think you should have put this inside a moist bag and let it cure really slowly for over 2 weeks or so. The slower the cure the stronger the concrete gets.
Well worth the time to do it right. As my Aunt Emma used to say, Prepare in leisure to use in haste. Well done ! ! ! PS I used to pour huge bridge abutments, and to insure a good cure, we covered the concrete with burlap, and had a water sprinkler going for the first few days. Water enters into the hardening reaction. Hardening/setting is NOT drying out.
Agreed. I am the son of a civil engineer and I should have known better. I can remember him saying that "concretes greater strength the wetter it is during the curing process." This, when I was 10-years-old. However, remembering and doing are different things. That said...my channel is about process. I've gotten lots of good comments about a 28-day cure time and keeping the concrete damp during that time. I'll be doing it right the next time. Thanks for contributing to the conversation.
Brother, at 21:34 you have the best version in my opinion. You just dont need a J tube. The rocket stoves made of square steel tudung kick butt with a J tube. You need inner strength form #9 wire, hog wire or even a tomato basket to make this thing rock! Great job Brother!
Nice improvement with the J-Tube. Radially place the bricks for a V-Shaped tappered toward the stove, it will create a Venturi effect and increase inlet volume for more fuel. Line the bottom under the grate with Aluminum sheet pan shaped for quicker ash removal. Stainless Steel sheet would last longer, but this is budget build and Aluminum will do fine.
Greetings from the UK. Love your experimental videos. If you are only using them to cook maybe you won't need a J tube thingy. Don't worry about the crack just put a band of thin metal like on a barrel around it. I am learning with you so keep up the good work. I especially like the fact you use the basic resources and tools because not all of us have a professional workshop to hard. The bent bit of metal screwed to a scrap bit of wood is pure genius. Georgia red clay on hand is amazing. Their will always be experts out there telling you what you should have done but you are learning for yourself. From all your female watcher's keep up the good work.
Mexican clay-ware "fireplaces" come with instructions since they are not fired in a kiln. You set 3-4 small fires first and let it fully cool down. This "fires" the "stove." Then they are ready for full duty. Another idea is to use refractory cement for higher temperatures. An armature will not prevent cracks. But it will keep the cement from falling to pieces. (Ask any concrete finisher...) To get the flames to swirl, place the j-tube as far off center as possible.
Thanks for the ideas, Og. I'll have to try the smaller curing fires in my next build. There were a couple other comments to this effect. I just get too excited about the big burn. :-) Thanks for the suggestions.
former stucco cat here. IMHO there was too much water in your mix (watching the first vid). mix should be like peanut butter in consistency without seeing any of the peanut oil. Thanks for the vid. Cool stuffs.
if you have cracking issues and are worried about structural issues you could get some large house clamps or link multiple house clamps together to make a big clamp then clamp around the exterior to assist in keeping it together. it would be similar to but you see on a wood barrel where they have the metal clamp rings around it.
You are an inventor. With each prototype you gain valuable knowledge to be applied to the next version. Well done. Maybe for the vertical chimney a piece of double wall stove pipe with the crete around that.
If your grill was running in the same direction of your wood feed then the wood would slide. As it is the bars are an obstacle to the wood sliding. I tried your fire brick design and I made this change and it helped.
Using a fiber glass mat to line the chimney will help insulate the flue. You can get the matting at most hardware stores. They use it to wrap hot water heaters and line newer metal lined chimney. When using matting pack it with refractory cement. aging this is in the fire place area.
Sorry this is 7 months late, but .... Love the video and the J tube is part of the features that make the rocket stove really interesting. From what I have seen, there is no ramp, it is an actual 90 degree angle J that feeds the fire. The fire is drawn up the chimney because the chimney tube stays hot. You already resolved that by insulating the tube so that it continues to create that strong draw. Because of that strong draw, the fire at the bottom of your feed tube is drawn sideways and does not heat up the feed tube to create another chimney. An issue that you might find is that the grate at the bottom of the firebox may hinder the airflow or draw of the oxygen through the fuel. That can be easily solved as well by making a solid bottom of the firebox where the fire is actually burning, and then having the hole at the bottom of the chimney collect the ash drawn in by the air flow. Seal off the airflow from below the grate and only use that as the way to remove the ash. Because of the efficiency of the rocket stove, there should never be any actual coals unless you are stopping the fire. This is the video that I has originally learned about the rocket stove, but what needs to be watched is the video that is refereed to in the video that was attached. ruclips.net/video/qtFvdMk3eLM/видео.html This video shows you a great image of the what the feed system should do when it is working. ruclips.net/video/_jfag47dRCs/видео.html
Thanks for the feedback and the links. I do plan to make a proper rocket stove some time soon. I’ll take a look at those videos. No comment or idea is ever too late...I’m still teachable. :-) Thanks for watching.
Insulation causes the inner wall to expand faster than the outside. Perlite is full of air that will expand and contract destroying the stove and may also cause small explosions making the stove unsafe. Finding what dose not work is just as important as finding what will work and if others know what dose not work then you have not wasted your time.
Also the Perlite is used to upgrade soil conditions to store moisture for some gardening. Could be the Perlite had moisture in the rocket stove and help develop the crack.
You have the grate to allow for ash removal below the flame. Create the J tube for automatic feed but allow the area below the grate to assist your draft. The channel under the grate is ideal to control fire intensity. Use two bricks at the base or front of this channel. Move them closer together to restrict draft and farther apart to allow more air to the fire. This will allow you to stuff the J tube as full as you wish while maintaining proper air flow beneath the fire.
Thanks for the suggestions Steve. Will definitely be leaving the air channel open under the grate. I was just using the bricks for a temporary J-tube. I will likely make a couple versions of the final, but I'm thinking steel and the same concrete-perlite mix I used for the stove. Thanks for watching.
Jthanks for sharing....no smoke coming out means very high temperature inside and super heated air. Excellent progress using low budget materials. Real research and development. I had similar issues when design f35 raptor jet exhaust materials, plus sonic vibration problems. Please progress onto installing a copper coil heat exchanger so your beauty can produce hot water. Exciting.
Sir, just watched your show for the first time. Good one. As for you adaptation of the J tube, 2 things, if your grate runs the other direction, turn it 90 degrees it'll slide easier and it you allow more air in by gaping the ram support by using 4 brick instead of 2, not only will it allow more air in but it'll allow you to get the ash build up out. Keep up the good work. Michael
Hi Michael. Good feedback. I think I'm going to eliminate the grate when using the ramp. Using two layers of brick should create a better ramp gap like you are suggesting. Thanks for the comment. Thanks for watching.
Heat differential is what causes cracks, if the inside is hot and the outside is cold it will crack, You see the same thing in cast iron, and glass. You have to let the whole piece come to temperature at the same time, inside and outside so that it expands together and shrinks together and maybe you can minimize temp shock. Perlite insulates the inside from the outside causing the worst temperature differentials, while the inside expands the outside remains cold the pressure increases until you get a fault and a crack. Can't cheat thermal dynamics.
you could use a small pan for an ash collection box- Something like those army disposal rectangle ones with fold-in handle. In Australia we would need to be really careful of hot ash and coals and I would put them in a lidded tin to cool. they are great in the garden and compost .
Chicken wire is not a rebar because it doesn't provide structural strength but DOES prevent cracking. That is why you can see it embedded in plaster in some old Victorian homes and that is also why you put mesh on drywall seams. Just a thought...
Thank you for taking the time to share this with us. I would suggest that you look into using sodium silicate as a binder rather than cement, if you haven't already, on one of your future builds. And by the way I disagree with you about the train ... I think you could easily stop it if you really wanted to. :) Keep up the great work.
Coming from Philippines : its good to have like your videos , kind of we can save money to buy a precious LPG here in the philippines by doing this racket stove .. thanks bro.
Thanks for the feedback, Bert. I’m glad you like the videos. And I agree that rocket stoves can be used all over the world. Thanks for the feedback. Thanks for watching.
For your j-tube addition consider trying a vertical grate rather than horizontal. This was a breakthrough for me, seeing as it was "great" aid for the self feeding property of the design. Hopefully you enjoy the pun as much as I enjoy your channel!
Your sense of humor is welcome here. :-) I come from a family of punsters. My dad is the King of Corn. I didn't fall far from the stalk. When it come to joked-filled comments, I'm all ears. To your point, switching the orientation of the grate would be a great solution to the feed ramp problem. Thanks for the feedback and for watching, you cornball.
Anothee option is to do 2 molds like the original, Stacked on top of each other. That would give you that third hole and maybe even build a platform like a self feeding ranp or counter./shelf front feature. So many things to comment. Great ideas with the heat shield in the back cuz that would be a concern to avoid spreading fire or catching fast growing plants on fire. I love the bricks in the frontt of the design too. Along with the improvement to the rebar sticking out on top, another option could be to add another grate like the one for the ash on the bottim. Very cool. Thanks for sharing.
Perlite expands at high temperture which causes ordinary cement to crack down. Use refractory cement. Refractory cement uses binding materials with improved thermodynamic properties to reduce the risk of mechanical failure. It can also tolerate higher temperature compared to portland cement because it has high thermal resistance.
good work. May I suggest that the problem with crack may be an air bubble in the concrete. moisture in the bubble will crack anything if heated to stream. The lack of combustion with the j tube is most likely lack of oxygen. Try putting 2 bricks long ways, perpendicular to stove at farthest end. Instead of the bottom brick on the ground, cutting off air flow under the grate.
Careful using galvanized in or near fire, burning galvanized metal puts off poisonous fumes. Note on the crack, when a fireplace is created it is recommended that it is seasoned slowly because of moisture still in the concrete. Heating quickly will cause the moisture to boil.
Hi Phil here Visqueen is just plastic and comes about 8 ft wide. make a pyramid and about 6 inches taller than your stove put it over the stove then cut the visqueen in a square senter it over the pyramid then flatten it on the ground then put a lot of dirt on it all around and seal it real good it will not work if it leaks. You should not see anything except for the pyramid frame covered with visqueen one single piece sealed with dirt. This is how they make statues they are very strong fingers are very strong they won't brahe off easy. The dryer you mix concrete the stronger it is if it has a lot of water in it when it drys it has holes in it where the water was and when the water dries out ir is weaker then dryer mix. When you pore it make sure it is stiff and packed real hard (TAMPED). Good luck have fun.
I'm sure someone else has pointed this out all ready but you were killing your underdraft with j-tube construction. When the feed port is full of fuel, the air was having trouble getting into the combustion area. Maybe use some perforated bricks at the front of the j-tube or construct it in a way that it can still draft under the grate. I also think that it would be interesting to use crack resistant concrete with the pearlite to offer a bit more stability to the final structure without having to use the chicken wire.
Hi Eric. I initially had the angled brick sitting up on the grate to allow airflow underneath. But the full feed port was definitely not helping. My second prototype rocket stove used crack resistant concrete (with chicken wire) and it hasn’t cracked. I’m going to try a variety of applications so I can do a proper analysis. Thanks for the suggestions.
You're not a packrat - you're a resourceful creative. I've thrown away things that I NOW realize would have been very useful & have to re-purchase - it's crazy. Some things I can't even get anymore. Creative people should never throw away resources. It's the first sign of maddness! LOL and thanks.
If you use portland cement and prepare the perlite in a blender till its a fine powder then just add a little silica sand it will handle temps way better. Thats how i made refractory cement for my knife making forge. It turns into something closer to ceramic when you reach temps over 1000 degrees
I've been watching these being built and burned for a long time and have one suggestion for you; which could give a greater burn rate with a better rocket sound. Deepen the air intake area to bring it more in line with a ratio of 60/40, air to fuel mix. I believe you will be very pleased with the increase. Good fortune!
Maybe consider using a smooth rain gutter j tube channel system to feed the fuel and using plenty of sticks and twigs while using gravity to force-feed the sticks and twigs into the chamber?
I enjoy your videos, since you have scrap metal you could wrap the grates that stick out. I think it would make a smooth surface for the wood to slide into the fire box and the air to come from under.
I would like to see a complete unit. maybe a tray that pulls out like on a toaster, instead of a bent piece of metal screwed to a stick. Great video. I am going to make one myself.
Thanks for the feedback. I agree that it works great as in. I do want to experiment a little with the addition of a j-tube or a few. But, I'll definitely be using this stove as is. Thanks for watching.
Don't choke the air entry. If you put the bottom metal grid sideways, the wood may slide in instead of getting stuck on the bars. Could you try a metallic drain "U" cannal for a feeder? It would remove a lot of surface roughness, allowing the wood to slide into the burning chamber.
Ha! There are certain tools I won't try from Harbor Freight...nails guns being one of them. I saw your comment pop up in notifications on my phone and all I could see was the "That's the best use yet..." Had to come to the desktop to see the rest of your comment. lol. Thanks for watching.
I was just making a smart ass comment, but actually I've had great success with HF nail and staple guns. I've run many thousands of nails and brads in the large and small guns and never had any issues whatsoever.
The grate was a good idea ,giving you 2 parts to the fire box.Top and bottom.Then you closed off the bottom chamber.There went your fresh air for rocket sound.
With your feeder in place it is stopping your air flow or draw. Maybe you need to cut a hole somewhere away from the milk jug hole for a draw if you are going to use j feeder. You still need a way to control your flame.
Hi Scott. I did a foundry out of perlite and plaster of paris, but in a 5-gallon metal paint bucket. It hasn't cracked like this rocket stove did. I think the metal containment would work for the perlite and concrete mix too. Thanks for watching from just down the road. :-)
To avoid cracks put rice hull. I use 1 part sand 1 part rice hull. Your cement depends on how strong you wanted it to be. Also it needs to be thicker. Mine never cracked even it only got 1 day curing( I need it right away). Seven days is good curing. 30 days is the best.
Marlin, thanks for the feedback. First time I’ve gotten the rice hull idea. Interesting. Also interesting that you fired after one day and no cracks. Thanks for watching.
There's a RUclips video entitled "Smelting Iron in Africa" posted by Christopher Roy. The folks in West Africa used to use clay mixed with chopped grass/straw to build their furnace. Somehow it helped with expansion problems (possibly like rice hulls?) and most certainly helped a bit to prevent cracking while it dried before the first firing. The video had a lot of interesting stuff, especially the "bellows" made from animal hides.
Let me start off by saying I'm no expert. Making your chimney taller might help to create more draft and really get the "Rocket" effect you are looking for. Also after it's warmed up play with restricting the air flow from below. Might help to channel a faster more concentrated stream of air down the j tube rather than a nice easy breeze from underneath. I appreciate your hard work. I'm waiting for you to work out all the bugs before I build mine. Thanks.
Thanks for the feedback and suggestions. My process is definitely an exploration, so I appreciate your ideas...especially airflow restriction. I’ll have to play with that. Thanks for watching.
Nice build. I've seen on other YT channels where they build a stove out of loose fire bricks, without locking them together w/cement. This allows the stove to breath naturally, plus you'd be able to dismantle it if you wanted. But, still nice build.
Very cool, I'm not an expert but just thinking outloud my suggestion is. On the extra one or one does the road, make the stove in two half long ways. with reinforcement wire. Told hold the two haves with two bands, tightened with flat cluplers. For a gasket, a strip of fire stove cloth, like one uses for fire stove doors. I have no idea if it will help or work. Fun to watch. Thanks
lack of drying likely contributed to cracking. Any metal introduced into the concrete is also a potential source of cracking. I saw a glass fibre mesh being used to prevent cracking in cement render when our house got external insulation added. The mesh came on a roll and was about the same rigidity as thin cardboard so should be easy to use. perhaps this might be of use? I have also used chopped up ceramic wrap in the mix when making kiln bricks and it seems to do a good job in reducing cracks. It is much like glass fibre insulation which is much cheaper.You can buy chopped glass fibre strand on ebay and it should be perfectly adequate for this type of stove.
Two ideas you might try on the next one. Keeping the first fire small and the. Letting it cool before a full on fire might help avoid cracks. If you offset the milk jug to the pvc riser you might get more swirling, maybe 1-2 inches of offset. For the feed ramp angle I’d suggest trying 45-60 degrees based on other videos I’ve seen.
Thanks for the ideas, Ian. I definitely am hearing a lot of "steeper feed" comments, so that will be a must in the next iteration of this rocket stove. And I'd like to get some swirl going too. Thanks for watching.
Some ideas: 1. You could also use some of that left over galvanized roofing to make a small three sided box (keep the front open for air) to catch the ash and then it would be even easier to clean out. Pull the box, dump easily and neatly somewhere for the garden, put it back. You won't be scraping it out and then having to rescoop it up from a pile on the ground in the dirt. : ) 2. Also maybe your next one you can bend the rebar over so that each of your pot standoffs have like and 1" to 1.5" piece pointing toward the center, then your stove can accommodate different (smaller) cooking vessels. : ) 3. For the J-Tube if you are using odd shape things like twigs and sticks the sides need to be smooth so there is nothing for them to catch on as they, hopefully, slide in. It would also need to be pretty steep so gravity is working more on pulling the pieces down into the fire than holding them laying sideways against the bottom of the ramp, so unfortunately probably more than 45 deg which might be impractical. Then tube itself has to be placed higher so that as the stick go in they do not hit the grate right at the bottom of the tube. It has to slide out of the tube and into the chamber such that it hits the other side of the chamber before it hits the grate at the bottom, Otherwise the stick will stop at the bottom of the tube and never make it to the fire. 4. Lastly, if you could somehow shape the center with some kind of swirl pattern, like gun barrel rifling, but a bit mare aggressive groves, it should work better. Maybe grease up some pieces of 0.5"x2" rubber insulating gasket etc. Maybe take three or four pieces and twist them up around the center tube such that they make one complete revolution from the bottom to the top. Don't want it to wrap around and around because if the wraps are too tight it won't make the air swirl it will just be like the sides are rough that's all. Some common sense eyeballing as you build it to decide on how many pieces and how many wraps around per piece should work fine. : )
Just found you! Great idea. But if you make the rails if your grate go the other direction it will feed a lit better. And if you turn your heat shield around so you have a dead air space it will be more efficient too.
I love it! Great job and ideas..very practical with simple things a bucket bottle and cardboard all recycled things..Also I never heard of pearlite in with concrete that's amazing..
Looks like your having fun. Big picture: Consider abandoning J tube design if primary operation is going to be cooking. Most cooking activities are short in duration in comparison to normal longer duration heating applications. Higher firepower, ease of managing combustion chamber (cleaning & operation) and use of non-uniform fuel is going to be more efficient. J tube designs were created for heating (rocket mass heaters) and long duration burns using uniform fuel. Gravity is a great friend using uniform fuel (i.e., pellets or uniform sticks), for self feeding functions. Non-uniform fuel is more efficient pushing in stove on a horizontal plane. Unless you want to spend time preparing fuel ,the J tube design for cooking may work against practical cooking operations. Cooking & heating are different applications. Biomass cook stoves with horizontal side feed is intentional and designed to accommodate different shaped found fuel ( sticks, branches, palm fronds, corn cobs, peanut shells, etc...). More fuel, higher fire power, less fuel lower firepower cooking. Side fed fuel control is typically easier with more precise control. By sticking a J tube on the side of a rocket cook stove does not turn it into a self feeding appliance. That is a misconception. Biomass fuel, unless prepared is just going to lay in tube unless manipulated. In summary, we find horizontal feed offers more controlled cooking functionality. Long duration cooking is performed more efficiently with TLUD batch stoves. Todd Albi, SilverFire Stoves & Cookware
I'm with you Todd. I love how this stove works just like it is. The addition of the grate to life the fuel boosted the burn big time. But...I am an experimenter and I have wanted to try the addition of a J-tube to the stove. I think I'll follow your recommendations for long-term use. I'm glad you mentioned peanut shells. I've been saving my pistachio shells for my worm towers, but I may give them a try as fuel. Thanks for the info.
If you poured this in a steel bucket as the outside shell expansion wouldnt be an issue? Also gives a place to attach by sheet metal screw any accessories. ..love your crowd sourcing info, works for your viewers as well..good work!
i think instead of making pot holding stubs you should mold grooves in the top of your chimney to allow air flow. then you wouldnt have to worry about any rusting or fumes from the metal or the metal causing the stove to crack by transferring heat improperly. then you could put your cookware right down on the top. also incorperating the grate by molding your stove around it raising it an inch or so off the ground would make this model bit better. more portable and less need for the bricks to raise entire stove. im still very new to these stove myself but thats just my 2 cents worth. keep up the great work!
I think the J should have a horizontal bottom 1/3 as long as the chimney is tall. The feed end should be vertical and 1/4 to 1/3 the chimney height. Your fuel should be placed vertically, replenished by levering in new branches from the back. As the tips burn, it will slump down into the firebox. A wire hoop a few inches above the feed can keep longish twigs from falling out if they get hung up as the tips burn. I did something like those dimensions when I made a bamboo core rocket stove (just buried in the ground and minimal soil around the chimney and feed.) It worked quite well.
The grate will keep the J-tube from feeding the fuel into the fire - the wood would hang up. Refractory cement is made for high heat applications. Refractory cement would still crack as all concrete does even at normal temperatures. Cracking occurred because of differential heating - the inside surface expanded quicker than the outside surface. Refractory cement is used to coat surfaces that face the heat source (inside wood fired pizza ovens for example). I've seen where these rocket stoves are made from heavy gauge metal (4"-6" round or square tube)l. Some are placed inside a metal drum slightly larger than the rocket stove and filled with Perlite as the insulating medium. I would consider making them out of metal if you have the welding equipment.
Dan, thanks for the feedback. I plan to try a metal one in the somewhat near future. Have welder, but need to hone the skills a bit. :-) Thanks for watching.
Have you ever tried when lighting the stove, put the wood in the regular spot and putting the starter paper in the ash part to keep from snufing the fire ? Tom Noteboom
I like seeing people actually putting their ideas into practice. "J - tube" I say it should be completely vertical, the chimney effect should cause the burn to be pulled sideways into the "chimney" and help with gravity feeding the fuel into the burn. You gotta make sure you keep the scale proportions correct (chimney taller than the "J - tube") so your chimney still pulls a vacuum, as opposed to just burning vertically in your "J - tube"... and don't block your airflow. As long as it's air tight, and you have the proportions right it should pull a solid vacuum (once you get it started).
Thanks for the feedback Nathan. In fact I'm headed into the backyard to build and test out a feed ramp idea. J-tube will be coming soon, but I need for design time, so I can be sure to get the proportions correct, as you are suggesting. Thanks for watching and taking the time to comment.
You could rake up all of the twigs and dried leaves and whatnot, mulch them and pour them into your bucket with a bit of water to make a paste-like solution. You could make a small form that would allow you to pour the solution into the form and make small briquettes of mulch that are sized to fit right into your burn chamber. You could even make the form out of a pvc tube so that the briquettes can roll freely down the feed ramp, and sized to be a bit shorter in overall length than the width of the burn chamber. Since the briquettes would all be uniform size and shape, and made of similar materials, you could accurately predict burn length, and set up your feed ramp in such a way that the only management you need to do is keeping the ash escape clean. You would then be maximizing the amount of found-fuel that you can use, keep your yard clean, have predicable burn times, and lower the amount of maintenance that you need to perform on the fire. You could even add scrap paper (junk mail, paper packaging material, news papers and the like).
1 Add a secondary air inlet at 90 degrees to your fuel feed chamber ( a 1 or 1.5 inch pvc pipe inserted through a hole in the centre pvc should do the job) keep the lenght of this smaller pipe longer so you can grab snd pull it out first from the mold. 2) wet the stove twice daily with a hose or set it in a bucket of water to cure better. 3) use chicken wire as reinforcement, it does help 4) first do small fires to drive out the moisture from the cement, it will reduce cracking.
I really like the experimenting. I'm not a rocket stove expert but I'm thinking that the wood fuel needs to have more oxygen to burn more efficiently. Perhaps the air tubes incorporated into the side of the mold....? I know this is an older video. I'll do some binge watching to see what interesting things you've added. 👍👍
Besides adding wire to the form. See if you can get some fiber mess that is designed for concrete. The fiber mess is designed to add strength and reduce cracking. When mixing the concrete make it as dry as possible but workable. The wetter the concrete the weaker the mix will be. If you have a concrete plant near you they will sell you a bag of fiber mess.
Thanks. I think the crack might be necessary, but I'm going to try this again with a wire mesh armature. Will also be adding some banding to the stove to keep the crack from opening more. J-Tube was still experimental, but I'm getting a lot of good ideas from viewers on how to make it better. Thanks for the feedback.
on your previous non perlite stove try adding a metal skirt around the stove about an inch from the concrete with a piece to tightly cover the top gap between the metal and the concrete. Put an air vent on the opposite side of your feed opening and make a removable feed hole cap or door. the stove will draw in cold air from the outside, warm it with the concrete body of the stove then use that warmed air to burn your kindling. your cooking temp should increase and make even damp fuel burn better. a metal garbage can could be cut to do the job. lighting your rocket stove from the top not the bottom probably would stop cracking from happening and make your draw much faster. good work , I hope you try my idea, and keep the vids coming I'm now subscribed
My wife and I use lint almost exclusively for our fires. We have found that making sure that it is fluffy with plenty of air in the fibers makes it burn better, rather than just smoldering.
J tube make it out of clay fire place linener. It's comes in rectangular shape in short halfs blocks. It's smooth and grinds or cut pretty easy. The J tube angle to hit the back of the fire box, no idea just thinking out loud.
You may want to make the J tube at an angle where the bottom of the J tube lines up in a direct line with the bottom back of the fire box...that way the wood will self feed and maximum wood will get burned in the fire box. Your new model currently has the bottom of the J tube lining up with the front of the fire box.
Perhaps adding a second hole on the side, at a 90 degree entrance to your firebox hole will allow for extra air intake, improving combustion efficiency. 90 deg. would be better than one going all the way across, as that would likely push the fuel out the other side, not what you want. Less risk of snuffing your fire as fuel is added since there would be an independent oxygen feed. Probably 1/2 the height of your milk bottle size would do it.
I think it would have been better for me to let this cure the full 28 days. And not cover it during the curing process. The moisture from the rain would have been beneficial. I’m still learning. :-) Thank you for watching.
Better feed if you pull back the grate so your fuel will reach the other side of the vertical chimney. Draw a diagram side view of the middle of the stove and formulate your feed angle for this to happen.
So, Heat shield is a required need. things you don't need galvanize poisoning AKA metal fume fever.. give that a check and if you think your life is worth it, possible change that metal out nearly any other ferrous metal. Also, for the J tunnel, you need to have the angle ramp meet at the back of the chimney so it feeds more to the back of the stove. alternate option is to open the fire box door more so you can have the same angle you are using with the same chimney.
Thanks for the warning. I agree on the J tube angle, getting the fuel more to the back of the firebox. I'm planning to angle the roof of the firebox in my next build. Thanks for watching.
Love the three videos, Love to see you trying to community improve the design.But the air vent from the bottom needs to be blocked off during use, it can be opened when cleaning. But the rocket really moves when they air flows from over the fuel.
I think the wood is getting hung up on the grate preventing the self feed. Perhaps having the grate bars going in the same direction as the wood may help the feed (smaller twigs will more than likely fall through though...).
Maybe use steel mesh instead of chiken wire to help with stability. As for self feeding j-tub, I'm seeing one that more resembles an upside down hollow capital t. The horizontal cross of the t built out from underneath the grate will keep the air ram open. Then just at the opening in the stove, angle the vertical part of the t at about a 35° angle to feed the wood. I wish I could draw here.
Notices you are using Phillips screws....try Robertson screws...seems alot easier to me! Also, if you used two different diameter chimney inside your design (8'' tube, perlite layer, 6'' tube, nails or screws to keep it together while pouring concrete), would that help you control the expension of the concrete better and maybe avoid cracking?
Tom, from what I have seen, you should make the j-tube to attempt to have the wood stand straight up. That way the wood will feed itself into the burn chamber as the ends burn off. The cross sectional area of the j-tube should be equal to the burn chamber which should equal the x-section of the riser. If you want to use a grate under the wood, put it at the bottom of the J-tube to hold the bottom of the wood. Also, you might not want to have the additional air feed under the wood as that might encourage the fire to creep up the wood standing in the tube. Of course, this is an experiment, so just continue to experiment to see what works best. The fire should pull all the way from the bottom of the sticks standing in the J-tube through the burn chamber and into the riser without any problem if the whole thing is sealed up properly. I would have the wood lined up right against the outside of the stove and let the air pull through the wood into the stove. I think folks have found that this works best if there is a small piece of metal that keeps the wood off of the edge of the j-tube closest to the stove. This helps air to travel down on both sides of the wood which provides a little bit of secondary air in the burn chamber.
Good feedback and suggestions Michael. I'm haring a lot of "more vertical" on the feed. I'm headed in that direction. I'm definitely an experimenter though...so we'll see what happens. :-) Thanks for watching.
I have a suggest: for the ash, you can take thin scrap metal of some sort, (am appealing to your pack rat nature) you can use large tin cans, attach them together, make sure the tray fits loosely into the space for ash, you can still use your ash moving tool.(techincal term,AMT!. sorry. best wishes kind fellow!
Enjoy the vids! A few friendly pointers from an old retired building guy:
Dryer mix, stronger concrete,
Rebar or wire mesh (fencing) for reenforcement, 28 day cure is an industry standard.
Smallish fires early on, then gradually hotter later. Excellent DIY..
Great job man!
I love hearing tips from those who know these materials from long experience. I’m definitely listening. I’ll be doing another refined build, incorporating a lot of the feedback and suggestions that have come via the comments. But, I may call it the “Parnell method” given that you’ve summed it up so nicely. Thanks for the feedback and encouraging words.
I have talked about building one of these to supplement a backyard fire ring for my father. As an almost-retired concrete guy, he agrees with the mix looks a bit too wet to start off. A wire mesh might be best for a small project like this, centered around the middle of the cylinder inside concrete, especially when you have heating/cooling like this. He was concerned for the long term of the project with rebar sticking out the top rusting out and moisture getting into the top, recommended just setting pan/pot on top of small ceramic tiles of some sort. Also, might have some expansion cracking problems with the rebar if these standoffs heat up quicker than surrounding concrete often, and looks like this might happen with quick heat transfer path from fire to pot to standoffs. Also, I see comments already about using the more specialized high heat furnace concrete instead of the standard concrete with perlite mix and go easy on the initial fires to help avoid cracking.
A great design we will use without much modification though, and I'm sure your design has evolved in the past few months. A good combo of simple and effective to supplement a fire ring for doing some of the initial cooking using just small backyard wood. edit: Yep, looks like some more video content with evolved design. Good stuff.
@@GreenShortzDIY kaolwool is a awesome liner to prevent the concrete from being a huge heat sink and it comes in rolls
@@stressmasterbk4294 Quick question: Where can you get kaolwool? And what the hell is kaolwool?
@@Jaden48108 Kaowool is a blanket of flexable cermaic insulation that is like 99.99% refractive to heat. fireplace supplies have it but it is available on amazon as well. www.amazon.com/s/ref=nb_sb_noss_2?url=search-alias%3Daps&field-keywords=kaowool
I made a smelter and a fordge out of it recently
You are the Pioneer of this project for me. I have simulated this with scraps and concrete. Using an entire 80lbs bag of crack-resistant concrete with a small $4 bag of Perlite in a 7gallon bucket curing right now. I ran out of material and in fact, the concrete settled full 1.5" for the top after tapping the sides for 30+minutes. The perlite has a lot of air to persuade out to the top... The armature was made of an unsellable refused stainless steel mesh filter from work. I used the Stainless steel expanded mesh metal sheet, rolled it into a double-layered cylinder and wired together. I made 4 cuts from one end through both layers to preserve the round while folding it over for the opening space. Then I cut a 4" refused papertube just taller than the bucket and used the cut-off for the opening molding. Strategically, I used stainless steel cuttings from cloth hangers to suspend the mesh cage around the tube and opening. I know, long story but, there's a lot... Last night, I dumped concrete mix inside the mesh against the tube because you will need to, it doesn't flow through. Made me believe the core could be slighty different Perlite mixtured ratios for the experienced; I am not experienced just an observation... So now my opening is 1.5" short because I was out of concrete and it settled deeper than anticipated. Today, I purchased Mortar cement and another small bag of Perlite. I made a mold with an old plastic oil pan using your cardboard+tape method on everything. Finally, mixing 10 scoops of Perlite and 2 scoops of mortar cement to perfection I made an additional Stand for the "wind channel" instead of bricks. I really needed to tap it with a hammer handle vertically to get the cream to surface because the Perlite kept packing down more and more with all the abstract edges. Last thought, I'm really hoping the "C" shape Stand of insulated concrete will controll expansion separately from the tower. I made a fire-brick puck of the remaining mix in a cup for a test sample under a torch. I hope the simple rolled steel mesh cylinder with extra folded layers over the opening with keep the stone together. I apologize for the long story I hope it helps anybody else who was anxious to try this project. So, $23 in total.... I'm anxiously waiting a month from now before I burn anything substantial or ripping hot.
If this works out all credit goes to you for the Inception, and if I failed, it will completely be on me lol. It's almost backyard season here ugh....
THANKS AGAIN!
Hi Derber. Your rocket stove project sounds like it is coming together nicely. This comment got stuck in the "possible spam" folder. Thus my not responding until a couple days later. I had to find it. Let me know it turns out. Especially the torch test.
GreenShortz DIY it's all good.
Ireland: love your thinking behind your project, problem solving all the time.
That is what life is all about. Find the need, try to solve it, never be afraid to fail as you have just eliminated one problem. Go again and have pride in what you finish. I love what you have finished and hope you much success, god bless
Thanks for the good word, Michael. I appreciate the encouragement. Thank you for watching.
Michael Conaghan
Problem is he is not thinking but instead taking everyone’s advice. Trying to please everyone else is what created his problems!
@@domingue4god He has no problems! He is making good money off of every ones comments and suggestions. A few epic fails fuels his helpers to keep commenting. Good job dude! I hope you get rich!
This is great! I think you should have put this inside a moist bag and let it cure really slowly for over 2 weeks or so. The slower the cure the stronger the concrete gets.
Thank you Ricardo. I like the bag suggestion. I definitely need to cure the concrete better. Thanks for the feedback.
Well worth the time to do it right. As my Aunt Emma used to say, Prepare in leisure to use in haste. Well done ! ! ! PS I used to pour huge bridge abutments, and to insure a good cure, we covered the concrete with burlap, and had a water sprinkler going for the first few days. Water enters into the hardening reaction. Hardening/setting is NOT drying out.
Agreed. I am the son of a civil engineer and I should have known better. I can remember him saying that "concretes greater strength the wetter it is during the curing process." This, when I was 10-years-old. However, remembering and doing are different things. That said...my channel is about process. I've gotten lots of good comments about a 28-day cure time and keeping the concrete damp during that time. I'll be doing it right the next time. Thanks for contributing to the conversation.
I like this guy, he's down to earth.
Brother, at 21:34 you have the best version in my opinion. You just dont need a J tube. The rocket stoves made of square steel tudung kick butt with a J tube. You need inner strength form #9 wire, hog wire or even a tomato basket to make this thing rock! Great job Brother!
Using harbor freight coupons for fire starting. Those savings are so hot! Lmao
Burn, baby, burn. :-) Thanks for watching.
great attitude regarding constructive and positive criticism
Thanks for the kudos. And for watching.
Nice improvement with the J-Tube. Radially place the bricks for a V-Shaped tappered toward the stove, it will create a Venturi effect and increase inlet volume for more fuel. Line the bottom under the grate with Aluminum sheet pan shaped for quicker ash removal. Stainless Steel sheet would last longer, but this is budget build and Aluminum will do fine.
Thanks for the ideas and honesty. Please, another update on rocket stoves!!
I can't believe you started the fire with a Harbor Freight ad!!!! LOL
:-) You're not the first to notice. Thanks for watching.
Greetings from the UK. Love your experimental videos. If you are only using them to cook maybe you won't need a J tube thingy. Don't worry about the crack just put a band of thin metal like on a barrel around it. I am learning with you so keep up the good work. I especially like the fact you use the basic resources and tools because not all of us have a professional workshop to hard. The bent bit of metal screwed to a scrap bit of wood is pure genius. Georgia red clay on hand is amazing. Their will always be experts out there telling you what you should have done but you are learning for yourself. From all your female watcher's keep up the good work.
Mexican clay-ware "fireplaces" come with instructions since they are not fired in a kiln. You set 3-4 small fires first and let it fully cool down. This "fires" the "stove." Then they are ready for full duty. Another idea is to use refractory cement for higher temperatures. An armature will not prevent cracks. But it will keep the cement from falling to pieces. (Ask any concrete finisher...) To get the flames to swirl, place the j-tube as far off center as possible.
Thanks for the ideas, Og. I'll have to try the smaller curing fires in my next build. There were a couple other comments to this effect. I just get too excited about the big burn. :-) Thanks for the suggestions.
Also, don't overfill the j-tube. Allow for some airflow and for movement, the sticks will sink into the tube more easily.
OgMandin0 zzz
YOU ARE VERY RIGHT --FIRE SLOWLY MULTIPLE TIMES WITH LOW HEAT AND IT SHOULDN'T CRACK--PATIENCE PADAWAN
former stucco cat here. IMHO there was too much water in your mix (watching the first vid). mix should be like peanut butter in consistency without seeing any of the peanut oil. Thanks for the vid. Cool stuffs.
if you have cracking issues and are worried about structural issues you could get some large house clamps or link multiple house clamps together to make a big clamp then clamp around the exterior to assist in keeping it together. it would be similar to but you see on a wood barrel where they have the metal clamp rings around it.
I see you already watched the follow up video. :-) thanks for the feedback.
You are an inventor. With each prototype you gain valuable knowledge to be applied to the next version. Well done. Maybe for the vertical chimney a piece of double wall stove pipe with the crete around that.
If your grill was running in the same direction of your wood feed then the wood would slide. As it is the bars are an obstacle to the wood sliding. I tried your fire brick design and I made this change and it helped.
I think I’ve decided feed ramp or grill, but not both. :-) The fire brick stove is one of my favorites.
Using a fiber glass mat to line the chimney will help insulate the flue. You can get the matting at most hardware stores. They use it to wrap hot water heaters and line newer metal lined chimney. When using matting pack it with refractory cement. aging this is in the fire place area.
Thanks for the tip, Tim. I've got a furnace build coming up and will have to use the fiberglass method for that project. Thanks for watching.
Sorry this is 7 months late, but ....
Love the video and the J tube is part of the features that make the rocket stove really interesting. From what I have seen, there is no ramp, it is an actual 90 degree angle J that feeds the fire. The fire is drawn up the chimney because the chimney tube stays hot. You already resolved that by insulating the tube so that it continues to create that strong draw. Because of that strong draw, the fire at the bottom of your feed tube is drawn sideways and does not heat up the feed tube to create another chimney. An issue that you might find is that the grate at the bottom of the firebox may hinder the airflow or draw of the oxygen through the fuel. That can be easily solved as well by making a solid bottom of the firebox where the fire is actually burning, and then having the hole at the bottom of the chimney collect the ash drawn in by the air flow. Seal off the airflow from below the grate and only use that as the way to remove the ash. Because of the efficiency of the rocket stove, there should never be any actual coals unless you are stopping the fire.
This is the video that I has originally learned about the rocket stove, but what needs to be watched is the video that is refereed to in the video that was attached.
ruclips.net/video/qtFvdMk3eLM/видео.html
This video shows you a great image of the what the feed system should do when it is working.
ruclips.net/video/_jfag47dRCs/видео.html
Thanks for the feedback and the links. I do plan to make a proper rocket stove some time soon. I’ll take a look at those videos. No comment or idea is ever too late...I’m still teachable. :-) Thanks for watching.
Small fires to bake the stove for a few times. the heat expanded the cement too quickly due to too much heat.
Yes. Good suggestions. You’re not alone in that feedback. Many others have offered that as well. We’ll call it good company. Thanks for watching.
Insulation causes the inner wall to expand faster than the outside. Perlite is full of air that will expand and contract destroying the stove and may also cause small explosions making the stove unsafe. Finding what dose not work is just as important as finding what will work and if others know what dose not work then you have not wasted your time.
Also the Perlite is used to upgrade soil conditions to store moisture for some gardening. Could be the Perlite had moisture in the rocket stove and help develop the crack.
You have the grate to allow for ash removal below the flame. Create the J tube for automatic feed but allow the area below the grate to assist your draft. The channel under the grate is ideal to control fire intensity. Use two bricks at the base or front of this channel. Move them closer together to restrict draft and farther apart to allow more air to the fire. This will allow you to stuff the J tube as full as you wish while maintaining proper air flow beneath the fire.
Thanks for the suggestions Steve. Will definitely be leaving the air channel open under the grate. I was just using the bricks for a temporary J-tube. I will likely make a couple versions of the final, but I'm thinking steel and the same concrete-perlite mix I used for the stove. Thanks for watching.
Jthanks for sharing....no smoke coming out means very high temperature inside and super heated air. Excellent progress using low budget materials. Real research and development. I had similar issues when design f35 raptor jet exhaust materials, plus sonic vibration problems. Please progress onto installing a copper coil heat exchanger so your beauty can produce hot water. Exciting.
Thanks for the good idea your channel just gave me a good idea for summer project
Looks like it works great dude. Well done.
Thanks Michael. I am pleased with the results. Thanks for the feedback.
Cool project thanks for sharing
Thanks for explaining so nicely
Don't let bad comments bum you out man.
The whole idea is cool
I'm curing mine at present :)
Sir, just watched your show for the first time. Good one. As for you adaptation of the J tube, 2 things, if your grate runs the other direction, turn it 90 degrees it'll slide easier and it you allow more air in by gaping the ram support by using 4 brick instead of 2, not only will it allow more air in but it'll allow you to get the ash build up out. Keep up the good work. Michael
Hi Michael. Good feedback. I think I'm going to eliminate the grate when using the ramp. Using two layers of brick should create a better ramp gap like you are suggesting. Thanks for the comment. Thanks for watching.
Love from indonesia, gonna make this project when i got home in the village.
Thanks for watching, Yoshi.
Heat differential is what causes cracks, if the inside is hot and the outside is cold it will crack,
You see the same thing in cast iron, and glass.
You have to let the whole piece come to temperature at the same time, inside and outside so that it expands together and shrinks together and maybe you can minimize temp shock.
Perlite insulates the inside from the outside causing the worst temperature differentials, while the inside expands the outside remains cold the pressure increases until you get a fault and a crack.
Can't cheat thermal dynamics.
you could use a small pan for an ash collection box- Something like those army disposal rectangle ones with fold-in handle. In Australia we would need to be really careful of hot ash and coals and I would put them in a lidded tin to cool. they are great in the garden and compost .
Just started watching your rocket stove video's, love them and great job. Thanks for sharing.
Thanks Ed! I appreciate the feedback. And thanks for watching.
Try ad a j tube inclination for ash also. So the ash drops easy .ad a ceramic fire rezistent tube inside your stove.
Chicken wire is not a rebar because it doesn't provide structural strength but DOES prevent cracking. That is why you can see it embedded in plaster in some old Victorian homes and that is also why you put mesh on drywall seams. Just a thought...
Thank you for taking the time to share this with us. I would suggest that you look into using sodium silicate as a binder rather than cement, if you haven't already, on one of your future builds. And by the way I disagree with you about the train ... I think you could easily stop it if you really wanted to. :) Keep up the great work.
Coming from Philippines : its good to have like your videos , kind of we can save money to buy a precious LPG here in the philippines by doing this racket stove .. thanks bro.
Thanks for the feedback, Bert. I’m glad you like the videos. And I agree that rocket stoves can be used all over the world. Thanks for the feedback. Thanks for watching.
For your j-tube addition consider trying a vertical grate rather than horizontal. This was a breakthrough for me, seeing as it was "great" aid for the self feeding property of the design.
Hopefully you enjoy the pun as much as I enjoy your channel!
Your sense of humor is welcome here. :-) I come from a family of punsters. My dad is the King of Corn. I didn't fall far from the stalk. When it come to joked-filled comments, I'm all ears. To your point, switching the orientation of the grate would be a great solution to the feed ramp problem. Thanks for the feedback and for watching, you cornball.
Anothee option is to do 2 molds like the original, Stacked on top of each other. That would give you that third hole and maybe even build a platform like a self feeding ranp or counter./shelf front feature.
So many things to comment. Great ideas with the heat shield in the back cuz that would be a concern to avoid spreading fire or catching fast growing plants on fire.
I love the bricks in the frontt of the design too. Along with the improvement to the rebar sticking out on top, another option could be to add another grate like the one for the ash on the bottim.
Very cool. Thanks for sharing.
Thanks for the feedback and ideas, Ree!
Perlite expands at high temperture which causes ordinary cement to crack down. Use refractory cement. Refractory cement uses binding materials with improved thermodynamic properties to reduce the risk of mechanical failure. It can also tolerate higher temperature compared to portland cement because it has high thermal resistance.
Cool stove.Try to put thin rebar bent into loops and weld them to the vertical bars. That way it will be more sound even if it cracks.
Thanks for the suggestion. Thanks for watching.
good work. May I suggest that the problem with crack may be an air bubble in the concrete. moisture in the bubble will crack anything if heated to stream. The lack of combustion with the j tube is most likely lack of oxygen. Try putting 2 bricks long ways, perpendicular to stove at farthest end. Instead of the bottom brick on the ground, cutting off air flow under the grate.
Careful using galvanized in or near fire, burning galvanized metal puts off poisonous fumes. Note on the crack, when a fireplace is created it is recommended that it is seasoned slowly because of moisture still in the concrete. Heating quickly will cause the moisture to boil.
Check this out, I found it rather interesting. Removing galvanization with an acid (vinegar). ruclips.net/video/bi466qkzQ3k/видео.html
Hi Phil here Visqueen is just plastic and comes about 8 ft wide. make a pyramid and about 6 inches taller than your stove put it over the stove then cut the visqueen in a square senter it over the pyramid then flatten it on the ground then put a lot of dirt on it all around and seal it real good it will not work if it leaks. You should not see anything except for the pyramid frame covered with visqueen one single piece sealed with dirt. This is how they make statues they are very strong fingers are very strong they won't brahe off easy. The dryer you mix concrete the stronger it is if it has a lot of water in it when it drys it has holes in it where the water was and when the water dries out ir is weaker then dryer mix. When you pore it make sure it is stiff and packed real hard (TAMPED). Good luck have fun.
I'm sure someone else has pointed this out all ready but you were killing your underdraft with j-tube construction. When the feed port is full of fuel, the air was having trouble getting into the combustion area. Maybe use some perforated bricks at the front of the j-tube or construct it in a way that it can still draft under the grate. I also think that it would be interesting to use crack resistant concrete with the pearlite to offer a bit more stability to the final structure without having to use the chicken wire.
Hi Eric. I initially had the angled brick sitting up on the grate to allow airflow underneath. But the full feed port was definitely not helping. My second prototype rocket stove used crack resistant concrete (with chicken wire) and it hasn’t cracked. I’m going to try a variety of applications so I can do a proper analysis. Thanks for the suggestions.
You're not a packrat - you're a resourceful creative. I've thrown away things that I NOW realize would have been very useful & have to re-purchase - it's crazy. Some things I can't even get anymore. Creative people should never throw away resources. It's the first sign of maddness! LOL and thanks.
I can't agree more. :-) Thank you for watching.
If you use portland cement and prepare the perlite in a blender till its a fine powder then just add a little silica sand it will handle temps way better. Thats how i made refractory cement for my knife making forge. It turns into something closer to ceramic when you reach temps over 1000 degrees
Carl, thanks for the idea. I think I'll give that a try. I've got an old blender that will be perfect for that purpose. Thanks for watching.
great result the fire seemed to get up and running much quicker with a more rockety roar .. maybe a bit too hot for first burn .
That is always my challenge...limiting myself to a small fire. The pyro in me always wins. Thank you for watching.
I've been watching these being built and burned for a long time and have one suggestion for you; which could give a greater burn rate with a better rocket sound.
Deepen the air intake area to bring it more in line with a ratio of 60/40, air to fuel mix. I believe you will be very pleased with the increase. Good fortune!
Maybe consider using a smooth rain gutter j tube channel system to feed the fuel and using plenty of sticks and twigs while using gravity to force-feed the sticks and twigs into the chamber?
Pretty cool. Be neat if you could come up with some type of flue arrangement so you could adjust the heat.
I enjoy your videos, since you have scrap metal you could wrap the grates that stick out. I think it would make a smooth surface for the wood to slide into the fire box and the air to come from under.
I would like to see a complete unit. maybe a tray that pulls out like on a toaster, instead of a bent piece of metal screwed to a stick.
Great video. I am going to make one myself.
don't overthink the stove, forget the j tube, it works fine with out the j tube god bless
Thanks for the feedback. I agree that it works great as in. I do want to experiment a little with the addition of a j-tube or a few. But, I'll definitely be using this stove as is. Thanks for watching.
Don't choke the air entry. If you put the bottom metal grid sideways, the wood may slide in instead of getting stuck on the bars. Could you try a metallic drain "U" cannal for a feeder? It would remove a lot of surface roughness, allowing the wood to slide into the burning chamber.
To help keep the crack from getting bigger try large hose banding strips. Like the ones used for pool hoses.
Thanks for the suggestion, Darrack. I'm planning to give hose clamps of some kind a try. Thanks for watching.
that's the best use yet I've seen for a Harbor Freight catalog ;)
Ha! There are certain tools I won't try from Harbor Freight...nails guns being one of them. I saw your comment pop up in notifications on my phone and all I could see was the "That's the best use yet..." Had to come to the desktop to see the rest of your comment. lol. Thanks for watching.
I was just making a smart ass comment, but actually I've had great success with HF nail and staple guns. I've run many thousands of nails and brads in the large and small guns and never had any issues whatsoever.
The grate was a good idea ,giving you 2 parts to the fire box.Top and bottom.Then you closed off the bottom chamber.There went your fresh air for rocket sound.
Thanks for the feedback, Lou.
With your feeder in place it is stopping your air flow or draw. Maybe you need to cut a hole somewhere away from the milk jug hole for a draw if you are going to use j feeder. You still need a way to control your flame.
Hi from Tucker Ga. I was thinking about making a small foundry from those ingredients but now I’m second guessing the idea.
Hi Scott. I did a foundry out of perlite and plaster of paris, but in a 5-gallon metal paint bucket. It hasn't cracked like this rocket stove did. I think the metal containment would work for the perlite and concrete mix too. Thanks for watching from just down the road. :-)
To avoid cracks put rice hull. I use 1 part sand 1 part rice hull. Your cement depends on how strong you wanted it to be. Also it needs to be thicker. Mine never cracked even it only got 1 day curing( I need it right away). Seven days is good curing. 30 days is the best.
Marlin, thanks for the feedback. First time I’ve gotten the rice hull idea. Interesting. Also interesting that you fired after one day and no cracks. Thanks for watching.
There's a RUclips video entitled "Smelting Iron in Africa" posted by Christopher Roy. The folks in West Africa used to use clay mixed with chopped grass/straw to build their furnace. Somehow it helped with expansion problems (possibly like rice hulls?) and most certainly helped a bit to prevent cracking while it dried before the first firing. The video had a lot of interesting stuff, especially the "bellows" made from animal hides.
Let me start off by saying I'm no expert. Making your chimney taller might help to create more draft and really get the "Rocket" effect you are looking for. Also after it's warmed up play with restricting the air flow from below. Might help to channel a faster more concentrated stream of air down the j tube rather than a nice easy breeze from underneath. I appreciate your hard work. I'm waiting for you to work out all the bugs before I build mine. Thanks.
Thanks for the feedback and suggestions. My process is definitely an exploration, so I appreciate your ideas...especially airflow restriction. I’ll have to play with that. Thanks for watching.
Nice build. I've seen on other YT channels where they build a stove out of loose fire bricks, without locking them together w/cement. This allows the stove to breath naturally, plus you'd be able to dismantle it if you wanted. But, still nice build.
Very cool, I'm not an expert but just thinking outloud my suggestion is. On the extra one or one does the road, make the stove in two half long ways. with reinforcement wire. Told hold the two haves with two bands, tightened with flat cluplers. For a gasket, a strip of fire stove cloth, like one uses for fire stove doors. I have no idea if it will help or work.
Fun to watch.
Thanks
lack of drying likely contributed to cracking.
Any metal introduced into the concrete is also a potential source of cracking.
I saw a glass fibre mesh being used to prevent cracking in cement render when our house got external insulation added. The mesh came on a roll and was about the same rigidity as thin cardboard so should be easy to use. perhaps this might be of use?
I have also used chopped up ceramic wrap in the mix when making kiln bricks and it seems to do a good job in reducing cracks. It is much like glass fibre insulation which is much cheaper.You can buy chopped glass fibre strand on ebay and it should be perfectly adequate for this type of stove.
Thanks for the tips. I need to try some glass fibers, if I do another concrete build. Thank you for watching.
Two ideas you might try on the next one. Keeping the first fire small and the. Letting it cool before a full on fire might help avoid cracks. If you offset the milk jug to the pvc riser you might get more swirling, maybe 1-2 inches of offset. For the feed ramp angle I’d suggest trying 45-60 degrees based on other videos I’ve seen.
Thanks for the ideas, Ian. I definitely am hearing a lot of "steeper feed" comments, so that will be a must in the next iteration of this rocket stove. And I'd like to get some swirl going too. Thanks for watching.
Short piece (1’ plus) of metal electrical conduit works well as a stand-off, no-smoke-in-the-face blow-on-the coals nicety.
Some ideas:
1. You could also use some of that left over galvanized roofing to make a small three sided box (keep the front open for air) to catch the ash and then it would be even easier to clean out. Pull the box, dump easily and neatly somewhere for the garden, put it back. You won't be scraping it out and then having to rescoop it up from a pile on the ground in the dirt. : )
2. Also maybe your next one you can bend the rebar over so that each of your pot standoffs have like and 1" to 1.5" piece pointing toward the center, then your stove can accommodate different (smaller) cooking vessels. : )
3. For the J-Tube if you are using odd shape things like twigs and sticks the sides need to be smooth so there is nothing for them to catch on as they, hopefully, slide in. It would also need to be pretty steep so gravity is working more on pulling the pieces down into the fire than holding them laying sideways against the bottom of the ramp, so unfortunately probably more than 45 deg which might be impractical. Then tube itself has to be placed higher so that as the stick go in they do not hit the grate right at the bottom of the tube. It has to slide out of the tube and into the chamber such that it hits the other side of the chamber before it hits the grate at the bottom, Otherwise the stick will stop at the bottom of the tube and never make it to the fire.
4. Lastly, if you could somehow shape the center with some kind of swirl pattern, like gun barrel rifling, but a bit mare aggressive groves, it should work better. Maybe grease up some pieces of 0.5"x2" rubber insulating gasket etc. Maybe take three or four pieces and twist them up around the center tube such that they make one complete revolution from the bottom to the top. Don't want it to wrap around and around because if the wraps are too tight it won't make the air swirl it will just be like the sides are rough that's all. Some common sense eyeballing as you build it to decide on how many pieces and how many wraps around per piece should work fine. : )
Just found you! Great idea. But if you make the rails if your grate go the other direction it will feed a lit better. And if you turn your heat shield around so you have a dead air space it will be more efficient too.
I love it! Great job and ideas..very practical with simple things a bucket bottle and cardboard all recycled things..Also I never heard of pearlite in with concrete that's amazing..
Looks like your having fun. Big picture: Consider abandoning J tube design if primary operation is going to be cooking. Most cooking activities are short in duration in comparison to normal longer duration heating applications. Higher firepower, ease of managing combustion chamber (cleaning & operation) and use of non-uniform fuel is going to be more efficient.
J tube designs were created for heating (rocket mass heaters) and long duration burns using uniform fuel. Gravity is a great friend using uniform fuel (i.e., pellets or uniform sticks), for self feeding functions. Non-uniform fuel is more efficient pushing in stove on a horizontal plane. Unless you want to spend time preparing fuel ,the J tube design for cooking may work against practical cooking operations. Cooking & heating are different applications.
Biomass cook stoves with horizontal side feed is intentional and designed to accommodate different shaped found fuel ( sticks, branches, palm fronds, corn cobs, peanut shells, etc...). More fuel, higher fire power, less fuel lower firepower cooking. Side fed fuel control is typically easier with more precise control. By sticking a J tube on the side of a rocket cook stove does not turn it into a self feeding appliance. That is a misconception. Biomass fuel, unless prepared is just going to lay in tube unless manipulated. In summary, we find horizontal feed offers more controlled cooking functionality. Long duration cooking is performed more efficiently with TLUD batch stoves.
Todd Albi, SilverFire Stoves & Cookware
I'm with you Todd. I love how this stove works just like it is. The addition of the grate to life the fuel boosted the burn big time. But...I am an experimenter and I have wanted to try the addition of a J-tube to the stove. I think I'll follow your recommendations for long-term use. I'm glad you mentioned peanut shells. I've been saving my pistachio shells for my worm towers, but I may give them a try as fuel. Thanks for the info.
If you poured this in a steel bucket as the outside shell expansion wouldnt be an issue? Also gives a place to attach by sheet metal screw any accessories. ..love your crowd sourcing info, works for your viewers as well..good work!
Thanks for the information you provided. This is invaluable.
i think instead of making pot holding stubs you should mold grooves in the top of your chimney to allow air flow. then you wouldnt have to worry about any rusting or fumes from the metal or the metal causing the stove to crack by transferring heat improperly. then you could put your cookware right down on the top. also incorperating the grate by molding your stove around it raising it an inch or so off the ground would make this model bit better. more portable and less need for the bricks to raise entire stove. im still very new to these stove myself but thats just my 2 cents worth. keep up the great work!
I think the J should have a horizontal bottom 1/3 as long as the chimney is tall. The feed end should be vertical and 1/4 to 1/3 the chimney height.
Your fuel should be placed vertically, replenished by levering in new branches from the back. As the tips burn, it will slump down into the firebox. A wire hoop a few inches above the feed can keep longish twigs from falling out if they get hung up as the tips burn.
I did something like those dimensions when I made a bamboo core rocket stove (just buried in the ground and minimal soil around the chimney and feed.) It worked quite well.
Thanks for the feedback and design details. I will be going more vertical with the feed tube. Thanks for watching.
The grate will keep the J-tube from feeding the fuel into the fire - the wood would hang up. Refractory cement is made for high heat applications. Refractory cement would still crack as all concrete does even at normal temperatures. Cracking occurred because of differential heating - the inside surface expanded quicker than the outside surface. Refractory cement is used to coat surfaces that face the heat source (inside wood fired pizza ovens for example). I've seen where these rocket stoves are made from heavy gauge metal (4"-6" round or square tube)l. Some are placed inside a metal drum slightly larger than the rocket stove and filled with Perlite as the insulating medium. I would consider making them out of metal if you have the welding equipment.
Dan, thanks for the feedback. I plan to try a metal one in the somewhat near future. Have welder, but need to hone the skills a bit. :-) Thanks for watching.
I would suggest you get a metal strap binder and bind the stove top and bottom to prevent further splitting.
We are on the same page, Roger. Take a look: ruclips.net/video/86oliqfL-2I/видео.html
Have you ever tried when lighting the stove, put the wood in the regular spot and putting the starter paper in the ash part to keep from snufing the fire ? Tom Noteboom
I like seeing people actually putting their ideas into practice. "J - tube" I say it should be completely vertical, the chimney effect should cause the burn to be pulled sideways into the "chimney" and help with gravity feeding the fuel into the burn. You gotta make sure you keep the scale proportions correct (chimney taller than the "J - tube") so your chimney still pulls a vacuum, as opposed to just burning vertically in your "J - tube"... and don't block your airflow. As long as it's air tight, and you have the proportions right it should pull a solid vacuum (once you get it started).
Thanks for the feedback Nathan. In fact I'm headed into the backyard to build and test out a feed ramp idea. J-tube will be coming soon, but I need for design time, so I can be sure to get the proportions correct, as you are suggesting. Thanks for watching and taking the time to comment.
You could rake up all of the twigs and dried leaves and whatnot, mulch them and pour them into your bucket with a bit of water to make a paste-like solution. You could make a small form that would allow you to pour the solution into the form and make small briquettes of mulch that are sized to fit right into your burn chamber. You could even make the form out of a pvc tube so that the briquettes can roll freely down the feed ramp, and sized to be a bit shorter in overall length than the width of the burn chamber. Since the briquettes would all be uniform size and shape, and made of similar materials, you could accurately predict burn length, and set up your feed ramp in such a way that the only management you need to do is keeping the ash escape clean. You would then be maximizing the amount of found-fuel that you can use, keep your yard clean, have predicable burn times, and lower the amount of maintenance that you need to perform on the fire. You could even add scrap paper (junk mail, paper packaging material, news papers and the like).
Cool ideas. Thanks for the feedback.
1 Add a secondary air inlet at 90 degrees to your fuel feed chamber ( a 1 or 1.5 inch pvc pipe inserted through a hole in the centre pvc should do the job) keep the lenght of this smaller pipe longer so you can grab snd pull it out first from the mold.
2) wet the stove twice daily with a hose or set it in a bucket of water to cure better.
3) use chicken wire as reinforcement, it does help
4) first do small fires to drive out the moisture from the cement, it will reduce cracking.
Thanks for the suggestion Deepak. I'll give that a try on my next concrete rocket stove build. Thanks for watching.
I really like the experimenting. I'm not a rocket stove expert but I'm thinking that the wood fuel needs to have more oxygen to burn more efficiently. Perhaps the air tubes incorporated into the side of the mold....? I know this is an older video. I'll do some binge watching to see what interesting things you've added. 👍👍
Besides adding wire to the form. See if you can get some fiber mess that is designed for concrete. The fiber mess is designed to add strength and reduce cracking. When mixing the concrete make it as dry as possible but workable. The wetter the concrete the weaker the mix will be. If you have a concrete plant near you they will sell you a bag of fiber mess.
Thanks for the suggestion and thanks for watching.
Dang the fire was going good. Hate that the crack happened. The J Tube construction looked like it needs more work. Great video keep up the good work
Thanks. I think the crack might be necessary, but I'm going to try this again with a wire mesh armature. Will also be adding some banding to the stove to keep the crack from opening more. J-Tube was still experimental, but I'm getting a lot of good ideas from viewers on how to make it better. Thanks for the feedback.
on your previous non perlite stove try adding a metal skirt around the stove about an inch from the concrete with a piece to tightly cover the top gap between the metal and the concrete. Put an air vent on the opposite side of your feed opening and make a removable feed hole cap or door. the stove will draw in cold air from the outside, warm it with the concrete body of the stove then use that warmed air to burn your kindling. your cooking temp should increase and make even damp fuel burn better. a metal garbage can could be cut to do the job. lighting your rocket stove from the top not the bottom probably would stop cracking from happening and make your draw much faster. good work , I hope you try my idea, and keep the vids coming I'm now subscribed
Lint from the clothes dryer is a good fire starter !
My wife and I use lint almost exclusively for our fires. We have found that making sure that it is fluffy with plenty of air in the fibers makes it burn better, rather than just smoldering.
You can pack lint in empty toilet paper tubes for convenience.
J tube make it out of clay fire place linener. It's comes in rectangular shape in short halfs blocks. It's smooth and grinds or cut pretty easy. The J tube angle to hit the back of the fire box, no idea just thinking out loud.
You may want to make the J tube at an angle where the bottom of the J tube lines up in a direct line with the bottom back of the fire box...that way the wood will self feed and maximum wood will get burned in the fire box. Your new model currently has the bottom of the J tube lining up with the front of the fire box.
Thank you for the suggestion, Lori. I'll need to angle the roof of my fire box too, to make that work. Thanks for watching.
Perhaps adding a second hole on the side, at a 90 degree entrance to your firebox hole will allow for extra air intake, improving combustion efficiency. 90 deg. would be better than one going all the way across, as that would likely push the fuel out the other side, not what you want. Less risk of snuffing your fire as fuel is added since there would be an independent oxygen feed. Probably 1/2 the height of your milk bottle size would do it.
Does it matter if you use a more gradual firing method with smaller fires over a few days to break it in?
I think it would have been better for me to let this cure the full 28 days. And not cover it during the curing process. The moisture from the rain would have been beneficial. I’m still learning. :-) Thank you for watching.
Better feed if you pull back the grate so your fuel will reach the other side of the vertical chimney. Draw a diagram side view of the middle of the stove and formulate your feed angle for this to happen.
So, Heat shield is a required need. things you don't need galvanize poisoning AKA metal fume fever.. give that a check and if you think your life is worth it, possible change that metal out nearly any other ferrous metal.
Also, for the J tunnel, you need to have the angle ramp meet at the back of the chimney so it feeds more to the back of the stove. alternate option is to open the fire box door more so you can have the same angle you are using with the same chimney.
Thanks for the warning. I agree on the J tube angle, getting the fuel more to the back of the firebox. I'm planning to angle the roof of the firebox in my next build. Thanks for watching.
Love the three videos, Love to see you trying to community improve the design.But the air vent from the bottom needs to be blocked off during use, it can be opened when cleaning. But the rocket really moves when they air flows from over the fuel.
Cool. Thanks for the feedback. I'll have to try this when I burn the rocket stove again. Thanks for watching.
I think the wood is getting hung up on the grate preventing the self feed. Perhaps having the grate bars going in the same direction as the wood may help the feed (smaller twigs will more than likely fall through though...).
Whoops, looks like somebody already mentioned that. Great job on the videos.
Add a bottom air intake to the designing if the "J" tube elevating your burn chamber about 3 inches from the bottom. I hope this helps.
Maybe use steel mesh instead of chiken wire to help with stability. As for self feeding j-tub, I'm seeing one that more resembles an upside down hollow capital t. The horizontal cross of the t built out from underneath the grate will keep the air ram open. Then just at the opening in the stove, angle the vertical part of the t at about a 35° angle to feed the wood. I wish I could draw here.
John, I’m curious about your idea. Email me a sketch at Tom at GreenShortz dot com. Thanks for watching.
Notices you are using Phillips screws....try Robertson screws...seems alot easier to me! Also, if you used two different diameter chimney inside your design (8'' tube, perlite layer, 6'' tube, nails or screws to keep it together while pouring concrete), would that help you control the expension of the concrete better and maybe avoid cracking?
Tom, from what I have seen, you should make the j-tube to attempt to have the wood stand straight up. That way the wood will feed itself into the burn chamber as the ends burn off. The cross sectional area of the j-tube should be equal to the burn chamber which should equal the x-section of the riser. If you want to use a grate under the wood, put it at the bottom of the J-tube to hold the bottom of the wood. Also, you might not want to have the additional air feed under the wood as that might encourage the fire to creep up the wood standing in the tube. Of course, this is an experiment, so just continue to experiment to see what works best. The fire should pull all the way from the bottom of the sticks standing in the J-tube through the burn chamber and into the riser without any problem if the whole thing is sealed up properly. I would have the wood lined up right against the outside of the stove and let the air pull through the wood into the stove. I think folks have found that this works best if there is a small piece of metal that keeps the wood off of the edge of the j-tube closest to the stove. This helps air to travel down on both sides of the wood which provides a little bit of secondary air in the burn chamber.
Good feedback and suggestions Michael. I'm haring a lot of "more vertical" on the feed. I'm headed in that direction. I'm definitely an experimenter though...so we'll see what happens. :-) Thanks for watching.
Remove the rear block that's directly opposite the fire wood entrance to accommodate more air flow when the bunch of fire wood blocks the entrance.
Great job
What about a tray under the grate to catch the ash? Easy enough to reomove and take the ash with it.
I have a suggest: for the ash, you can take thin scrap metal of some sort, (am appealing to your pack rat nature) you can use large tin cans, attach them together, make sure the tray fits loosely into the space for ash, you can still use your ash moving tool.(techincal term,AMT!. sorry. best wishes kind fellow!