First of all, what is a Tandoor? A Tandoor is a clay oven that originated in India. It is how Naan Bread is made. The design is simple with no moving parts. Where most wood fired ovens cook on the floor, food is cooked in the tandoori on the side walls or on skewers. My Tandoor cooks in the 600-900 degree range. Because of the high heat, some people call Tandoors the "Indian Microwave"
Tandoor Oven
As you will notice there is a 2 inch or so vent hole at 10-11 o'clock to allow air flow into the coals at the bottom.
Here is a video of a tandoor in India being used to cook Naan Bread. Naan Bread Video.
So now that we have the concept of a Tandoor here are the benefits to building your own oven as opposed to purchasing one. The cost is significantly less. I did mine for less than 200 bucks, comparing this to a residential model that run in the 600-1000 dollar range that is not bad. Another huge draw is that you easily can entertain people and this provides an excellent atmosphere for socializing. This is an easy project, it took me a couple of days, but I only worked on it for a few hours at a time.
What you need:
55 Gallon Drum (Used is preferred, but make sure it held nothing toxic. More on how to prep the barrel in step 1. DO NOT use a Galvanized Trash can, there are many plans on the internet for this, but Galvanized steel vents off Zinc at toxic levels when heated)
Large Flower pot (Mine was an 18 inch thick rimmed pot, a thinner rim could get you a larger pot)
Fire Brick 15-20 should be plenty (these are the thick ones)
Fireplace Mortar 2-4 tubes (NOT Fireplace Sealant, the big home improvement stores do not carry this, so look for it at ACE it comes in a caulk tube)
2-3 Bags of Sand
2-3 Bags of Crush and Run
Tools you will need
Angle Grinder w/ Diamond Wheel
Optional: Wet Saw
Caulk Gun
3 inch hole saw
Eye Protection
Dust mask
Step 1: Prepping your Barrel
If you bought a new barrel you can disregard this step, but build a hot fire in the barrel to burn off all of the residual contents of the barrel. Once this cools rinse the barrel out and give it a good scrub to allow it to dry.
You can leave the barrel unpainted, but it will rust. My barrel was a professionally refurbished one, so I did not prep it. I kept the original paint on the outside. My barrel only gets to 140 degrees on the out side, so you could go with regular paint, but I would recommend a high heat paint.
Step 2: Cutting the Flower Pot.
You will need to mark a line all the way around the pot with a permanent marker as you will be cutting off the bottom of the pot.
After you have marked, don your eye protection and dust mask. And using your diamond wheel cut very slowly. The important thing is to keep your blade parallel to the pot bottom as you cut. My diamond wheel cut through the flower pot like a hot knife through butter. Just to reiterate the point of needing eye protection and a dust mask, this gets really dusty you can see the terracotta dust on the grass. Save the part you cut off, it makes a great lid.
Step 3: Cut the Air Vent on the Flower Pot
Measurements do not have to be exact, but a 3 inch hole is perfect. I just free handed this with the diamond wheel. Was the pot thoroughly and allow it to dry in the sun. The original top of the pot is now the bottom.Step 4: Finding the Level of your Pot
It is very important that you have your Barrel in the spot you want it. When we finish this step it will weigh a bit much to move easily. If you have the ability to make a set of wheels to attach to the bottom this would make it easier to move if you needed to later.You want to have about 2-3 inches from the flower pot to the lip of the drum. You also have a layer of fire brick under the flower pot, so you need to figure that out. I used a piece of chalk to mark the level for the layer of fire brick.
Now slowly fill the barrel with the crush and run. Taking time to pack it well before adding more until the level where you will build the fire brick layer.
Step 5: Making Your Fire Brick Platform
This is probably the most difficult step. When I build a second tandoor, I plan to make a bowl of firebrick instead of the flat layer. This way I could have a slightly larger capacity.Cut all of your brick to fit. Remember, you do not have to cover the full layer in the barrel, just enough for the pot to sit on. This is where a wet saw would come in handy, but I cut all of mine with a 4.5" diamond wheel on my angle grinder. I had to cut all 4 sides, but I could then break the brick and grind off the little stump. A little crude, but it got the job done.
You can see in the picture above where I cut all sides of the brick and then just had to break it.
After I dry laid out all of my brick, I mortared them in place with the tubed fire place mortar. You will get some of this on the brick surface, you can wipe away the excess with a wet rag.
Like I said, not pretty, but you are likely the only one to see it. I put a few good globs of the mortar in the corners to keep it from shifting. You will see in the finished pic it looks much better, I used the uncut brick in the middle where the would be seen, and also where it would require the fewest cuts.
Step 6: Drilling Your Vent Hole
This is easy, but you want the bottom of the hole to be as close to the fire brick as possible. I just drilled from the inside out. Take a good file or even better a Dremel Tool and grind out the rough spots.Step 7: Placing Your Flower Pot on the Firebrick Base
Test fit your pot. make sure you have a good level base. If not mark the pot and apply a little extra fireplace mortar.If your test fit is good, apply a thin layer of the fireplace mortar to the bottom (what was once the top of the pot). Place the pot on the fire brick making sure you have the air hole lined up with that of the one on the barrel.
Step 8: Creating the Air Tunnel
I unfortunately have no pictures of this step. I essentially made and mortared a tunnel out of peices of fire brick to connect the hole on the flower pot to the hole in the barrel. Be very liberal with the mortar.Step 9: Fill It With Sand
Fill the area between the barrel and the pot with sand to about 2 inches from the rim of the pot.Let the fireplace mortar Air Dry for a day or so. Then start a chimney starter full of lump charcoal and slowly add charcoal so that you slowly warm the mortar and flower pot. Your goal is to take 1 hour to reach 500 degrees. Then push it to 800 degrees and try to keep it there for another 30 minutes. Do not cook on it while you do this .
Finally top of the sand with a layer of pea gravel to keep it from blowing around if it is windy.
Step 10: Cook
So now you are ready to cook, well, not yet. You still need a set of skewers and we still need to discuss some safety rules.First the safety rules.
Never pour liquid into a Tandoor until it is cool. The ceramic can shatter violently.
Keep your skewers in a safe place where children will not be able to hurt themselves.
Never leave your Tandoor going if you are not going to be around it.
As far as skewers go, you can find many online, I got 8, and a Naan Hook and Scraper for 60 bucks from Nishi Enterprises. I was very pleased with the quality, these skewers will last for years. I recommend 4, 6mm, and 4 4mm.
To store your skewers, I keep them in a 3" PVC Pipe that I have glued a cap to the bottom and one that I can remove from the top.