At first, I wasn’t sure what I wanted to use for the top surface of the side tables. I dug through my pile of scrap/salvaged/recycled materials and found an assortment of stone, tile, steel, aluminium, and wood.
I simply set different pieces of materials on top of the side-arm pipes to see what looked good. In the end, I decided on a blue/green slate stone for the left side and a steel deck place for the right side.
For the steel on the right, I just welded the pipe flange to the bottom of it, threaded in the short section of the pipe, and slid that into the slightly larger diameter vertical pipe. A horizontally-drilled hole with a bolt slid through it completed that side.
The slate for the left was a little more work. The slate was rough and pointed, but it is a very soft stone. I experimented and found that RUBBING the edges of the stone with a cold chisel allowed me to shape the stone a bit and smooth the rough edges.
To attach the stone to the side pipe, I found some scrap metal about the right size for the bottom of the stone side table. I welded the pipe flange to the bottom of the metal and then glued that to stone with a tube of “JB Weld” adhesive.
Again, the pipe on the side table just slides into the vertical pipe on the side of the grill.
Odds and ends:
The water tank section of the grill is painted, and the paint had to be removed before using the grill for cooking.
I thought about what the most “eco-friendly” way to remove all the paint was. I thought about all the nasty chemicals used as paint strippers. In the end, I decided to make a very hot test fire to both try out the grill and remove the paint. The paint easily peeled off.
To hold either the stock pot or Dutch Oven, there still needs to be air space at the bottom of the grill. The easiest answer was just to span the fire tube with two short sections of slotted C-channel.
They support the pot and let plenty of heat and air through. They are not welded in place. I didn’t see any reason to, and this way they are removable.
One downside of this grill design is that it gets an extreme hot spot in the middle of the grill, and is much cooler towards the outside edge. That’s a bad thing for cooking burgers and sausages. So input in a “heat-diffuser” when grilling.
It’s just a small steel plate that I practised welding on before welding the grill together. It simply sits directly on the pot bracket and works well to spread out the heat. At some point, I may make a more aesthetically-pleasing heat-spreader, but this one works fine for now.
You may have noticed that there is no ash clean-out on the grill. In truth, I really haven’t seen a design for one that I like. I have seen similar steel rocket stoves that use a threaded pipe port, which seems like it would gunk up the threads easy. Also, a large-diameter pipe port gets expensive quickly, and I was trying to use as many free, inexpensive, and recycled parts as possible.
For now, I just flip the whole grill upside down to empty the ash. It makes far less ash than you might think. In the future, I may use the angle grinder to cut an angle out the bottom back side of the grill, and then hinge it, so that there is a flip-up flap to access and empty the ash.
The grate is just a standard round grill grate. It’s a medium size. It actually overlaps the top of the grill, which makes it easier to use the entire top. Downside? It’s easier to slide a burger right off the top of the grill as well!
Fueling and firing: One of the best things about the Rocket Grill is how it’s fueled. No longer do I have to purchase fossil fuels to cook my backyard fare! Because of the amount of air that flows through the rocket grill, almost any biofuel burns great in it. This one is really designed for twigs and sticks.
After every windstorm, all of my neighbour’s trees shed their sticks downwind into my yard. Before, I would grumble at the yard work of picking up all those sticks and moving them back to the brush pile. Now, I instead gather them up looking forward to burgers, corn-on-the-cob, or whatever I am going to cook up next.
To start the rocket grill, I just put a little bit of tinder (usually a bit of newspaper) and a few twigs onto the far end of the Fuel/Air Plate. I light it with a match or cigarette lighter, and then just feed in a few more twigs. After that, a fair amount of sticks, firewood, or other fuel can be loaded on the top side of the fuel plate.
The fire is very simple to light and starts right up.
Even EXTRA LONG fuel can go right in. Just slide it a little farther in every once in a while. The chimney effect makes all the heat goes up the vertical tube. No smoke or fire comes out of the feeder tube.
I am right-handed, so I designed the rocket grill so that the feeder tube comes out at an angle to the right. That way, it is easy for me to fuel, but I don’t hit my shin on it.
Since pots sit down INSIDE the rocket grill when boiling, the heat transfer of the fire to the pot is very good. The heat hits not just the bottom of the pot but travels up the sides as well. This means you get a boil going faster while using less fuel.
I also used my rocket grill in a rainstorm a while back. My concern was rain running down the lid and then inside the rocket grill. It wasn’t an issue – any rain hitting the lid simply vaporized or sizzled right off!
Grill it up: So far, I have used the rocket grill for chicken, burgers, brats and sausages, corn on the cob, shish-ka-bobs, and more.
The design of the rocket grill also allows me to boil in the stock pot, or bake in the Dutch Oven. (I’m working on baked desserts now too!)
A friend of mine has designed both a giant skillet and a very nice wok for this. Another possible future modification is to create a high-thermal mass pizza oven top for the grill.
Rocket grills lend themselves well to infinite variation and reuse of existing materials. Combine that with versatility and efficient use of fuel and you have the cook stove of tomorrow, today.
Remember, this isn’t rocket science, just good use of appropriate technology!
I hope you find my Rocket Grill to be inspirational. You too can cook net-carbon-zero deliciousness over open flames and take pride in your own design.
Thanks to bennelson for this great project!