I've received many requests for firepit plans, and Duke Frederick of Holland happens to have come up with a design which is the best I've seen. Reproductions of it, many made under license, can be found all over the country (I've owned one of them for years). Duke Frederick has graciously consented to my publishing it here, subject to the restrictions at the end of the article.
The following design has been tested under various conditions in the West Kingdom since February, AS XVII (1983). It has been approved for use at any site which permits the use of hibachis by the West Kingdom Fire Marshall. The only repair it has required in that time is the replacement of the fire-grate after a year and a half of use.
The general design is shown to the left. It is a bowl which is a segment of a sphere suspended on a tripod which runs through holes in the bowl. In the bowl is a flat fire-grate made of expanded metal which holds the fire off the base of the bowl, keeping it cool and allowing a place for ashes to fall. The tripod additionally supports the grill on which you cook, or can be used to suspend a pot above the fir. The bowl is constructed of six fan-shaped plates which pivot on a central bolt and latch together with hooks to form a rigid structure. The fans are overlapped so that there are no open gaps through which coals might fall to the ground.
The dimensions of this pit may be adjusted to suit your own needs. I here give the general method of construction as well as the dimensions which I used for my pit. Refer to the plans. First decide what diameter you wish your pit to be, and how deep you want it. I decided that 30 inches diameter and 5 inches deep was about right if I was going to use the particular grill I had in mind, and the piece of scrap steel I had just found. The combination of the radius of the desired bowl, r, and the depth, d, determine p, the radius of the sphere from which the bowl will be "cut." This in turn determines the arc-length, s, from the center of the bowl to the edge. Both r, the radius of the bowl, and s, the distance along the bowl from center to edge, are necessary to measure the fan-pieces. Note that the difference between r and s for my firepit is only 1.1 inches. This is critical! The fans are designed so that they will be edge-to-edge only at the rim of the bowl and will overlap everywhere inside the bowl. The 2-inch width at the center was determined empirically and works fine.
I wanted to hold the bowl together with clips and I didn't want them to come out while the bowl was in use and perhaps jarred by a passer-by. I therefore put two clips on each of three of the fans and two slots for them on each of the remaining three fans. The clips are of 16-gauge steel and rivetted to the fans so that they can swivel. Note that the slits should be cut so that they are radial to the center hole, not parallel to the edge of the fan. Since the clips come over the top of the fans, the support rod holes are drilled in the fans with the slits. This means that all the forces generated by weight on the bowl will tend to hold the clips in the slits. In addition, the fans with the clips are on the bottom of the stack of fans, so that the natural springiness of the metal is working to keep the clips in. The fans are held together with a 1/2" bolt.
I originally thought that I could leave the metal plates flat and have them bend up naturally to form the bowl. Unfortunately, the 16 gauge steel doesn't bend all that easily, so I had to crease the fans as shown. The cross-ways crease is about 7" from the small end, and gives about a 2" elevation at that end. The radial crease runs in from the edge and gives about a 1" to 1-1/2" elevation of one flat with respect to the other. This amount of bend means that a certain amount of force is still necessary to hook the bowl together, which helps hold the hooks in place.
I made my fire grate out of medium-weight expanded metal (the light-weight won't hold sticks and such, and the heavy-weight was too expensive). I reinforced it by bending it into an octagon rather than cutting it. The fire-grate for my pit is 24" diameter. This puts it about 1-1/2" below the lip and well above the bottom of the bowl.
The tripod I made out of 1/2" hot-rolled steel rod. I flattened one end of each, drilled a hole, and put a heavy loop through to keep the pieces together. About 12" down I drilled a small hole and put through a hook to catch the chain that supports my cooking-grill. About 9" from the other end, I drilled a hole for the support pin for the bowl, and about 2" above that a hole for the cotter pin to hold the chain that acts as a keeper for the pin (to keep the pin from getting lost). I used nails for the hooks and pins.
The height of the tripod is largely a matter of taste and appearance. I used four-foot lengths of rod because that looked right and because it allowed for a certain amount of movability for the cooking grill. The lower the tripod, the less adjustable will be any given grill. The higher it is, the longer the piece of rod you will have to transport. My cooking grill is 15" x 24" and has three light chains brazed onto it, on at the end and two on either side about two-thirds of the way down. These I wrap around the tripod rods (to reduce sway) and then hook on the little hooks at the top. These stay cool and I can adjust the height of the grill while cooking by easing the strain on the chain, then adjusting it up or down in increments.
Notes on use: Although the bottom of this pit does remain cool, it is always a good idea to put a board under it if you are setting up on dry grass or in tall grass. If the fire danger is extreme, clear the area around the pit just as you would for any other fire.
IMPORTANT NOTE: Use of these plans to make a firepit for personal use is permitted and encouraged. If you are thinking of setting up in business making firepits, please talk to Frederick first to arrange licensing. He can be reached by writing or telephoning:
|3334 California St.|
|Berkeley, CA 94703|
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