Build a Rocket Stove
How to Make a Mud Rocket Stove
Rocket Stoves are designed to use small pieces of wood to cook food. These economical stoves are made of clay and organic material like rice hulls, sawdust, or manioc skin. The insulated chimney burns the oil and gases that create smoke, meaning these stoves will burn clean and cook food using less fuel. Below are photos showing how you make a Recho Roket.
Besides the clay and organic material you will need one 5 gallon bucket (pre-cut with a saw), a 12” length of 4” PVC, 1 cup of sugar (or the juice of rotting fruit), four 1 meter lengths of strong cord, a piece of flat tin 4” X 22”, two 14” pieces of 0.75” X 1.5” wood notched to match the top of the bucket and the PVC, one or two flat ended pieces of wood 2 feet long (or longer) for tamping in the clay mixture, one 4” long piece of wood, several gallons of water, a piece of thick cardboard traced and cut to fit inside the bottom of the bucket, with a hole in the center of the cardboard the diameter of the PVC.
Find a good source of clay without rocks. If there are a few rocks you can pass the clay through a 1/4” screen.
This is what the clay will look like once it’s mixed with the rice hulls or other materials. Good clay will ball together in your hand.
You need 1-1/4 buckets of clay and an equal amount of rice hulls, sawdust, or manioc skin to make one Rocket Stove.
Cut the bottom off a thick-walled 5 gallon bucket leaving it 12”-13” tall.
Then make a cut down the side of the bucket.
Cut a piece of 4” PVC that is exactly the same height as the bottomless bucket. Be sure the PVC is cut straight so that it stands straight.
Cut a cardboard circle outlined by tracing the inside of the bottom of the bucket.
Then center the PVC within the circle and trace around it.
Cut out the tracing of the PVC. The hole will hold the PVC in place as the bucket is filled with the clay mixture.
Tin or plywood could be used in the place of cardboard.
Two pieces of wood approximately .75” X 1.5” X 14” will need to be notched to fit onto the top of the five gallon bucket and the 4” PVC.
The cross pieces are notched to fit together. They will hold the PVC so that it stays centered when filling the bucket with the clay mixture.
Five gallon buckets vary in dimension so a set of notched sticks won’t necessarily work on multiple buckets. NOTE: The stove will be constructed upside down.
Boil 4 liters of water with some source of sweetener (2 or 3 rotten mangoes or grapefruits, bagasse, or sugar).
The hot water will make it easier to mix the ingredients and the sweetener will help bind the clay and organic material when dry.
Mix the ingredients very well with your hands until it can be shaped into a well-formed ball.
The ball should stay together when thrown on the floor. If it falls apart it is too dry but be careful not to get it too wet either or the stove will slump when the form is pulled off.
Tie four strong pieces of string around the bucket and tighten the string by twisting it with a short twig. This will hold the bucket closed while you fill in the clay mixture.
Pack the clay mixture into the upright bucket. Use sticks with flat ends to pack it well. Make sure the bucket does not bulge too much or lift off the ground.
Stop filling the bucket at 4” from the top. You will use a piece of tin 4” by 22” to form the mouth of the stove. NOTE: The clay was too moist in this photo and the stove slumped.
The bucket should have 2 slits cut in its top that are 4” apart and 4” deep. Wrap the tin around the PVC and slide it through the slits. The top of the tin should be even with the top of the bucket & PVC.
Place a 4” piece of wood between the tin to maintain a 4” mouth while the clay mixture is tamped up to the top of the bucket. Twine may be tied at the top lip of the bucket, above the tin.
Finish by making sure the clay mixture is level with the top of the bucket so the stove will not rock when it is dried.
Loosen the cords around the bucket and remove the tin and the PVC pipe. This can be done using pliers or....
...by placing your palms together and inserting both hands into the PVC pipe. Press hard against the inside of the PVC ...
... and gently draw it out of the stove slowly and carefully. If you’re unable to pull it out by hand, pulling with pliers will work.
NOTE: If the clay mixture is dry enough you will be able to turn the stove over before removing the bucket. (This is preferable.)
Remove the bucket form carefully. If the clay mixture is too moist you will not be able to turn the bucket over for a day or two because the wet stove will slump.
If you do end up having to turn a stove over several days after making it, be sure to put the bucket back around it before turning it over to avoid breaking or damaging the stove.
With wet hands, add extra clay to fill and smooth shut any visible cracks or holes.
The stove should look like this after the smoothing process.
One idea for a grate is to embed rebar at the bottom of the stove. Cut the rebar in 6” lengths. Be sure to mark the middle of the bars so you can see when they are equally embedded in both sides.
Place the bottom of the rebar 1.5” from the bottom of the stove. The rebar is poked into one side and then drawn back into the other.
The rebar should be about a finger width apart. Press additional clay into the stove sides (next to the rebar) until the rebar fits snugly without wiggling. 3/8” rebar is good. Use six 6” pieces of rebar.
Here is another idea for a grate, made of welded flat bar. Whatever you use, be sure that the gaps are perpendicular to the direction the lengths of wood are placed.
After extended cooking, this stove created charcoal because it did NOT maintain a good air space under the burning sticks. Using a proper grate will keep this from happening.
When the stove is turned over it will look like this.
Carve the stove top so that it is beveled about two inches wide ...
... using this tool. It will also give you the proper angle of the bevel.
Would you like to make this tool?
The Welcome page has a link to print a pattern.
Place this tool against the chimney wall to measure the angle, the length of the bevel and the height of the pot rests. This tool can also be used to smooth the clay.
Take some of the extra clay mixture and extend the flat surface on the top. Wet the surface of the stove so the clay you are adding will adhere.
Try to get the top of the stove to a diameter of at least 13 inches and make sure the extension is flat on top. This will provide a base for the very important pot skirt.
Once the stove top is extended, cut out three notches equidistant apart.
Mold some clay and place it into the notches and use the stove tool to get the proper angle and length of the pot rest.
Let your stove dry for 2 or 3 weeks before you use it. Keep out of the sun while drying to prevent cracking.
If you’re making stoves for sale, it would be a good idea to have a traceable design to put on all your stoves so customers will recognize your stoves.
The Welcome Page of this website has a link to download a diagram of this Rocket Stove Tool. Print it, cut out the paper shape, and then you can trace it onto....
... a piece of tin. Cut it out with tin snips to make your own tool.
The Rocket Stove on the right boiled 4 cups of water in 4 1/2 minutes using only small sticks. This was possible because we used a pot skirt, grate and a draft tunnel.
Pot skirts direct the heat around the pot. The pot skirt does not support the pot. The pot sits on pot rests.
When you make your pot skirt be sure to include spacers that maintain a 3/8” gap(one centimeter) between the pot skirt and pot. This 3/8” spacer was made with discarded tin cans.
The spacers on this expandable pot skirt were made pounding tin over a 3/8” bolt.
Can you see how this pot skirt is adjustable? The metal piece in the lower left is folded over the skirt, holding two pieces of tin in place....
... Unfold the pieces of tin to lengthen or shorten the pot skirt to best fit your cooking pot, then press it back in place again.
The previous pot skirt is a prototype made from a powdered milk can cut in half and spliced together. Skilled tinsmiths should be able to make these at a reasonable price.
Cut and bend a used tin can to hold the sticks up, creating a place for air to enter the fire under the burning sticks.
Draft tunnels concentrate the air which is important for making your Rocket Stove cook food hot, fast and without much smoke.
Use materials you have on hand to experiment and find what works best. A flattened milk can covers the clay sides of the draft tunnel.
Even with just small sticks, a properly built Rocket Stove creates enough heat to fry food without smoke.
