In a previous Instructable I made a smoker from an old expansion tank. It came out awesome, so I figured I would try making a larger smoker but could double as a grill, inspired by Japanese Kamado cookers ("Egg" looking bbqs). If you are not familiar with those types of cookers, they can be used as a smoker or grill.
The benefits of the kamado is they are incredibly efficient in their fuel use and they can grill at super high temperatures, mainly because it is made from ceramic. The ceramic construction is a good "insulator" and I use that term lightly as where the true benefits of the kamado stand out is thermal mass. I own a smaller kamado and what I dislike about the one I have is the cooking surface area is small and hard to load fuel once lit, however what I really like is when smoking meat, it can maintain an even 250F for long periods of time and use little fuel and not produce much creosote. The downside is with that thermal mass, it takes a while for the cooker to cool down or if you need to lower the temperature, it can take a while.
From here forward, I will refer to this smoker and grill as the "cooker".
So my criteria for this build is:
- Must have an ample cooking surface.
- Should be able to retain heat and be fuel efficient.
- Fuel source will be charcoal.
- Different levels of grates
- Have an easy way to add charcoal even with food in the cooker.
- Be able to smoke and grill.
- Have multiple cooking grates.
- Room for a water pan
- Be able to cook pizzas at high heat.
The following Instructable is a comprehensive write up.
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Step 1: Design and Video
I landed on an initial design dictated by the materials I have access too. My idea was to use mostly sheet metal for the "shell" and it would be insulated by clay or sand for the thermal mass. I decided that kitty litter which is clay would make a good substance for thermal mass and is easy to get. The shape would be a vertical box for simplicity but unlike the flimsy vertical smokers that can be purchased at Home Depot, my cooker would be made from thicker sheet metal. The only thing it would have in common is visually it would look very similar to a regular smoker.
Here are videos of the build and the cooker in use, the written instructions follow.
Step 2: Metal and Materials
Typical smokers and grills use 20 or 22 gauge sheet metal or thinner (at least the cheap ones) which is why they rust out and do not retain heat very well at all. The walls for the cooker in this build are 14 and 16 gauge sheet metal. The inside walls will be exposed to the most heat so they are constructed from 14 gauge and the outside walls will be 16 gauge to cut down on weight. The frame is made from 1"x1"x1/8" square tubing and the sheet metal was welded onto the tubing. The cooking surfaces are 3/4" #9 steel expanded metal and 1"x1"x1/8" steel mesh.
The fire basket is also made from steel expanded metal.
- Walls: 14 and 16 gauge sheet metal.
- Frame: 1"x1"x1/8" square tubing and 1" and 3/4" angle steel
- Cooking Surfaces and Fire Basket: 3/4" #9 steel expanded metal and 1"x1"x1/8" steel mesh
- Heavy duty casters
- Kitty Litter
- Various hardware hinges
- Misc bolts and nuts
- BBQ Paint
- BBQ Thermometer
- Welding Chipping Hammer
- Felt gasket material for BBQs (got mine from Amazon)
Step 3: Tools
This is a more advanced build as it requires the use of a welder. But anyone can learn to weld and this is a great project for anyone up for a challenge. I am by no means a great welder but I was able to build this.
If you are looking to learn how to weld I would recommend getting a flux core wire feed welder as it's easier to learn and can weld thin metals. I am using a sticker welder, mostly because that is all I have.
Also if you don't want to weld you could modify the design and get away with bolting the whole thing together or using a tap to tap bolt threads in the frame.
You will need but not limited too:
- Mini Grinder
- Grinding and Cutting Discs
- Chipping Hammer
- Welding magnets
- Basic hand tools
- Safety equipment (glasses, cotton long sleeve clothing, footwear, gloves)
- Welding Rods: 7018 for the structure, 6013 for the sheet metal or thin parts of the smoker.
A note about cutting discs, do not be tempted to buy cheap ones, they do not last and will disintegrate after a few uses. Buy quality bulk ones to save money, it will pay off in the long run and they are by far safer to use.
Step 4: Making the Frame
The frame is made from 1"x1"x1/8" square tubing. It is a box that measures 20"x19"x38"
Welding magnets were essential to help keep the whole box square. Also a template was made from some wood so two sides could be made and then they were welded together. Before welding anything I made sure to measure corner to corner and adjust as necessary to keeps things square as well. Ideally you would use a 3 position clamp but they are very expensive.
Heavy duty casters were then welded to the bottom and reinforced with some angle steel.
The top of the frame had some slots cut out, this is so the clay/kitty litter can be added after the fabrication.
Step 5: Adding the Inside Walls and Top
The inside walls are made from 14 gauge sheet metal.
First the the right and left sides were tack welded in place then the back was welded in place. I welded in small sections, moving to different parts of the frame to minimize warping. Ideally two extra 1"x1" tubes should have been staggered vertically that would help keep warping down.
The outside walls are made from 16 gauge sheet metal. It had a hole cut so the tube for the rotisserie could be welded between the wall. The walls were then welded all the way around, this is optional and only necessary since I will be filling the walls with clay/kitty litter.
For the ceiling some angle steel was welded so the sheet metal had a place to rest and then was welded in place.
Step 6: Doors and Air Intake
There are two doors for the cooker, the top one for access to the food and a bottom for checking on the fire.
These are filled with kitty litter as well and the bottom door will also need an air intake that can be choked to control the fire.
They are made from 1"x1"x1/8" square tubing, just like the frame, then covered with sheet steel. The latching mechanism is a tube welded in place in the doors and then a bolt, some steel is the latch and a chipping hammer serves as a heat proof handle.
The air intake was made by cutting out a square hole in the bottom door and some angle steel was used to make the sides of the intake. Some bar stock was welded on to make a slot so some sheet steel could slide back and forth as the choke. Long bolts were installed on the sliding chokes as handles.
The locking mechanism is: a piece of angle steel notched for the catch, the handle is a welding chipping hammer cut and welded onto a piece of 1/8" steel bar stock then bolted to the doors.
Step 7: Chimney
Chimney is a 4" metal dryer vent. I cut out a slightly smaller hole than the chimney on the top of the smoker. Then the flange was made by welding a strip of metal to the top of the cooker and then bending it and welding each bend in place until I had a nice round circle. I also pre-bent the strip of metal to help add the curve. I had to bend the top of the flange in a little before the vent would fit.
Step 8: Outside Walls
The outside walls are made from 16 gauge sheet metal and just like the inside they were welded in place.
Also welded in place was a tube near the center of the middle of the sheet metal for the inside wall, this is an opening for a rotisserie.
In hind sight, an extra piece of square tubing would have been good down the center of the wall for reinforcement. Since I did not do that to strengthen the walls I welded a piece of angle steel across the outside wall. Eventually I will use it to hang fire pokers and tongs off it.
Step 9: Installing Doors
The hinges are some simple square ones from the hardware store. They were welded and cut to size.
I temporarily taped the felt gasket giving me the correct gap, so I could install the doors.
The latching mechanism is a chipping hammer welded to a piece of barstock and bolted through the door.
Step 10: Cooking Grates and Fire Basket
The cooking grates are made from 1"x1"x1/8 wire mesh with some 1"x1"x1/8" bar stock welded around the outside for support.
The fire basket is made from 3/4" #9 flattened expanded steel sheet and wired together. Some angle steel was placed on the bottom of the smoker so air could flow under the fire and the ash has a place to collect.
Step 11: Cooking Grate Supports
The rails to support the cooking grates are 3/4"x1/8" angle steel. I added a few at different heights so there would be options to place the cooking grates.
Step 12: Removable Top and Filling the Walls
The top of the cooker is removable, so that if there was ever a reason to remove the clay it would be possible with out having to cut the top off. Some holes were tapped so bolts could be used to hold the top down.
Clay kitty litter was poured into the walls to serve as insulation and thermal mass.
Step 13: Side Table
Folding side table is made from finger jointed pine, stained and varnish. The folding mechanism was simply a 4' piece of 1/4" round stock bent in a "u". The hinges are some utility hinges. On the cooker some pieces of square tubing were welded and holes drilled so the round stock could rotate and fold. On the side table a "french cleat" was added so the round stock had a place to wedge and hold the table up. This is a very strong mechanism and works very well.
Step 14: Grinding and Painting
The whole cooker had the edges ground with a grinding wheel and then was polished with a flap disc and then scrubbed down with a scotch bright pad. High heat bbq paint was rolled on.
The stick on nomex felt gasket was applied.
A thermometer was added to the door. Ideally you want to install a few, so they are at different heights in the cooker as temperatures fluctuate in different parts of the cooker.
Cooker was completely washed down and scrubbed with soap and steel wool to remove any traces of the welding and residual from the metal.
Step 15: Finished Cooker
The cooker is completed. I did some grilling and it worked perfectly, held temperature with no issue at all. I was able to bring it up to searing temps and it stayed. The air intake works great and allows for little or a lot of air flow.
As a smoker the cooker functioned as expected, it held 250F and even with opening the doors to check on the meat it came back up to temperature quickly (1-2 minutes).
Even made pizza's on it! Using some 1/8" plate steel as the pizza "stone".