Just Another Smokeless Fire Pit From a 55 Gal Steel Drum

My old fire pit was rusted out and I was looking for a discount way to replace it. I started my hunt on Craigslist for fire pits and found them to be rather expensive, even for used and rusty. That led me on a Google learning journey about smokeless fire pits. There are a lot of different designs out there and a lot of different methods. This Instructable is aimed at teaching you some of what I learned as well as utilizing some free/discount options.

1. A 55 Gallon Steel Drum (prefer screw caps vs open lid type)
2. An old folding metal bed frame (we harvest the legs, the headboard mounts, and some of the frame)

1. Metal cutting tool (plasma cutter, tin snips, jig saw, sawzall, etc)
2. Hole saw or Step Drill Bit (optional)
3. Drill with bits
4. Cutoff wheel on a portable grinder
5. Metal attachment tools (welder, bolts, rivets, etc)
6. Safety equipment (leather gloves, eye and ear protection)
7. Ruler or tape measure (flexible clothing tape measure works the best on round surfaces)
8. Marking (pencil, marker, grease pencil, etc)
9. Hammer
10. Punch (to remove bed frame rivets)

It basically boils down to heated updraft causing secondary combustion. Holes on the bottom allow fresh air to enter outside the combustion area. This fresh air heats up and rises to top of the combustion area where it enters through more holes. This adds additional oxygen to the burning fuel as it leaves the combustion area, thus offering a more complete burn with less smoke. Holes on the bottom, holes on the top, and no magic smoke.

Barrels generally have two sets of ridges, some have more. This comes in to play when we design the height of the system. We will be using one of the ridges as a cover to the seam in the cut barrel since the ridge is slightly larger than the rest of the barrel diameter. We will be cutting the barrel into 3 pieces. One center piece will be roughly half the height of the barrel and the two remaining pieces (the top and bottom) will equal roughly the same height. I created a few variations of this when building my fire pits, and I will cover some of that near the end. Barrels are typically between 21-23 inches in diameter and 33-35 inches tall.

Barrels may contain combustible liquids and vapors. Please adhere to any warning labels applied or that may have gone missing. If your barrel is yellow/red/black, use extreme caution as those are typically a warning sign of volatility. If you do not have any labels or know what the contents of the barrel were, it is best to fill it with water before attempting any cutting that could cause sparks. Remove both caps (or the barrel end) when making the first cuts.

Once completed, you will be burning stuff in this fire pit that will impact the coating on the barrels interior and exterior. Do not cook food over this fire. Toxins may off-gas while burning.

The goal is to separate the barrel into FOUR pieces that will become our finished product: The lower base, the center ring, the inner grille, and the top ring.

I took some photos but they may not convey everything as intended, so I added an .MP4 video attached below.

Piece 1: The bottom of the fire pit. The top of the barrel with plugs (or lid latch) will be the bottom of the fire pit. The smooth bottom of the barrel will be the top of our fire pit. The first circumference cut I make is for the top of the barrel with the plugs (which is our bottom). This cut is typically around 6-8 inches from the end (depending on which variation you are creating). Cut all the way around the barrel. If your barrel is full of water, some has definitely leaked out at this point. It should now be safe to empty all the water. The next circumference cut will be just above the ridge as it bends back towards the normal barrel width, about 12 inches from the bottom of the barrel (the smooth lid end). I used a plasma cutter and a lazy suzan to spin the barrel as I cut. I used two different sized ABS plumbing pipes as a template for my holes when using my plasma cutter. If you are using a hold saw or step bits, you should not need a template. I used larger holes for the bottom outer ring of the fire pit. I placed 20 holes about 1 inch in diameter roughly 3 inches apart.

Using an angle grinder with a cutoff wheel, remove the rivets holding the bed frame legs on. Remove the bed frame legs. We will attach these to the base of the fire pit to get it off the ground. I attached mine with 1/4-20 bolts and wingnuts.

Piece 2: The inner ring. To make the inner ring, cut about 9-12 inches out of the side wall and rejoin the wall together. If welding, no overlap is required. If using rivets or bolts, generally about 1 inch of overlap is desired. Bending or holding the ring with a ratchet strap will assist in joining the seam. The first version, I welded with a stick welder. That is not recommended. MIG or TIG would be better suited for thin metal. The second version I used pop rivets and the third version I just used 1/4 inch bolts and wing nuts. I used smaller holes at the top on the inner ring, about 3/4 inch and 24 holes about 2.5 inches apart.

We will then use about 16 inches of frame next to the headboard tabs as legs to hold the bottom grille above the bottom of the fire pit. These attach to the center ring and also hold it up off of the bottom. This gap on the bottom between the grille and the lower part of the fire pit is a space where ash can accumulate without plugging the intake holes.

Piece 3: The inner grille. The inner grille is created on the smooth bottom of the barrel (which is now our top ring). Start with finding the center, draw two lines perpendicular from the center to form four quadrants, then subdivide them with lines again. I cut a center hole about an inch in diameter. I determine my inner ring size, and draw an appropriate sized hole depending on the version (same size hole for version 1 and 2, about 2 inches smaller hole for version 3). Then draw lines about 2 inches from the edge of that hole that intersect the 8 lines at 90 degrees. It should look like a pinwheel. Cut these lines with your cutting tools, do not cut all the way to the center hole, and do not cross to the outer hole. Then bend the 8 flaps downward slightly about 15-30 degrees. This creates some rigidity for the grille. Now make the cut for the inner ring size that we previously drew.

Piece 4: The top ring. This piece is already created when you cut out the grille in end of the last piece.

Welded inner ring seam. Ugly. Center ring sticks out the top, the flanges were cut with a tin snips, and sharp edges are dangerous. This method allows the inner grille to fit with no adjustment in size, the upper case holds the center ring in place.

Pop rivet inner ring seam. I plasma cut the top flange, but it is still a poking hazard. Upper case is holding the center ring in place.

Bolt and wing nut inner ring seam. No sharp edges, but fire will burn off half the paint on the top cover edge. Inner tabs are added to hold the center ring in the center. Since the top hole is smaller, the inner grille is too small, so I made a template to utilize the spare piece removed from the center ring circumference. Four wings added to the lower grille. Four small pieces of bed frame bolted to the outside of the inner ring to center it on the lower ring. Final outside looks nicer than the protruding flange on top (as in version 1 and 2).

There are probably a lot of adjustments that could be made, maybe a lot of scientific conclusions drawn from extended testing, but I have only made six so far. Not enough data and variance to come to any real conclusions other than it does help reduce smoke output. Adjusting the upper and lower hole sizes and quantity, adjusting the flange angles, and adjusting the lower grille height could all have impacts on the efficiency. This is not an exact science, but merely one method to convert an unused barrel into a backyard centerpiece to enjoy with company.

If you have an old Weber grill laying around, the covers are pretty close to fitting. Some vary from 22-23". Teal one shown, but I have a few spare black ones.