Building a Kamado, A.k.a. Weber Conversion Number Four

Since Barbecuing is one of my favorite hobbies, and building the things I want to have, another, it was only obvious my Weber barbecue had to be improved. Since conversions 1 to 3 are made a long time ago I will just describe them briefly, and do conversion number four in more detail.

It all started some twenty years ago, when I Bought my first Weber, on a discount, for a rather nice price I thought. At home I realized why the price was so friendly. I bought the kettle instead of the One Touch Silver. Basically, the same BBQ, only the kettle missed the ash container and butterfly air control fan in the bottom. This gave me two choices, bring it back to the shop, or to the workshop. Me being me, I chose the latter. Thought I could buy a few nice steaks for the money I’d saved.

Disk grinder

Welder

Hacksaw

Tyling tools

Regular plyers and such, just basic tools

The aircontrol:

The three air vent discs in the bottom where removed, and replaced with one butterfly wing made out of some scrap steel plate, bent round, so it fitted the bottom of the kettle snugly. In the center I drilled a 10mm hole, and welded a 10mm bolt on the wing. I drilled a hole in the kettle in the center of the bottom, and dropped the wing in from above. A piece of chrome plated rod 6mm was bent in a V shape, and welded to a M10 nut. I screwed this on the wing bolt sticking out of the bottom, and secured it with an extra bolt, and the air control was finished.

The Ash container:

For this I decided on a 20 cm stainless steel salad bowl from Ikea. I found a strip of aluminum 60mm wide, 2 mm thick, in the scrap, for the stationary part. I measured the circumference of the bowl, divided it by 4, and made 15 mm deep incisions on one side of the strip. To make the ears for the mountings. Then bent the strip in a circle around the 20 cm stainless salad bowl. The ears were bent 90 degrees, and drilled with a 5 mm hole. Execs material of the trip was removed with a hacksaw, to make the whole topside flush, and I made a groove for the air control handle. The strip was riveted to the bottom of the Kettle, and punched full of holes to have enough air for the fire. Next, I made three L shaped grooves in the bottom side of the strip, with three matching M6 bolts in the salad bowl, and we have a nice bayonet fixture for easy removal of the bowl. Then it was time to fix some steaks.

As I baked more and more in my nice BBQ, I figured I wanted more control over the temperature, so I needed to know how hot it was inside. So, I Invented a BBQ temperature measuring device. This was actually a Thermometer for deep frying. Which I mounted through a hole I drilled in the lid. In those days there was no thermometer in the lit, but later on Weber and others copied this, so I guess they still ow me some cash for the idea.

Unfortunately I couldn't find any pictures, only the broken thermometer in the shed, which died on me years ago. Luckily the big brands where by this time wise enough to ad a thermometer so I could get one from them.

As I continued grilling more and bigger pieces of meat, I figured it would be nice to have a rotating rotisserie in the BBQ. For this I used the parts of a broken combi microwave oven. The rotisserie itself was too short, but I could use the connection part to the motor and the motor itself. I cut of the connection piece and welded it to a stainless 8 mm rod. Cut it to the wright length and sharpened the end so it would easily go through the meat. For the mounting of the grill, I made a ring of some sheet steel plate, made of two parts. The first part was L shaped, about 20mm by 6mm. This was bent in a circle with the 6mm edge sticking out to the outside, exactly the size so it fits tight in the BBQ. The second part also L shaped, about 60mm by 6mm (both parts were made from a piece from the lid of cable tray), but bent with the edge to the inside. Both rings were welded together, so I had a ring with the bottom side fitting in the BBQ, and the top fitting in the BBQ lid. This way I could place the grill ring on the BBQ if needed, and remove it for grilling small meat.

 The motor was placed in a little sheet steel box, folded from the same lid as the ring, and bolted to the ring. To get some distance I used two 20mm spacers, then a small plate to act as a heatshield, 10mm spacers, all this so the motor box wouldn’t get to hot. I drilled a hole in the ring so the rotisserie could get to the motor, and welded a small piece of sheet steel tube, cut in half on the other side as a support for the rotisserie.

And I was happy, grilling wonderful pieces of meat for years and years.

Even tough I was quite happy with my BBQ, I got a little jealous, seeing more and more people getting the green eggs and sorts. So I started thinking. Should I buy one, for the ridiculous amount of money they are charging for these? Was this a good design? could it be improved? I decided they where far to expensive, and definitely could be improved, for a fraction of the cost.

First thing to do was getting more dept in the BBQ, so I made the BBQ ring 20cmm higher with some sheet steel, and bolted it to the bottom part.

This gave the problem the fire would always be deep inside the bowl, like the original green egg, which is very not good for very fast, very hot grilling of steak. I solved this by making a basket for the coal which is adjustable in height. I Fixed a tripod in the middle of the BBQ, with a 12cm tube sticking straight up. The tube is actually three tubes fitting loosely around another, and all cut with pipe cutter, so the have an edge going in. In the outside of the tubes, I made groves for the edges to glide in. I made a basket of round 10mm steel rod, one side round, one side straight, and welded the thickest tube to the straight side, and a 50 mm piece of 15mm tube for the handle. This way I could stick the handle in, pull up the basket, and when it’s released, it will, because its hanging on one side tilts a bit, so that the edge will fall in a groove and the basket stays in place.

Since all green eggs have a hinged lid for a good reason, the lids get a bit heavy, I also needed a hinge. I made this from some pieces of 30 by 30mm and 35 by 35mm square steel pipe. Because I wanted to be able to use the BBQ without a lid I decided it must be made so it could be easily removed. For this I cut a piece of the 30mm square pipe at an angle and welded it to the ring I made on the bottom of the BBQ. The bottom part off the hinge was made from the 35mm square which is just slid over the piece I welded on the ring. This way I could just pull of the whole lid when I wanted to.

I made a small chimney from stainless 50mm pipe, with a piece of the same pipe on top, cut to a round shape, and welded over the top, to keep rain out. Drilled an 8mm hole through about 10 cm from the bottom for the valve. The valve is made of an 8mm rod stainless through, which had a groove cut in to it, for an oval disk, cut to fit in the pipe. with a little wooden handle on one side. The spring on the rod is there so it stays fixed in the angle it’s placed.

The top part of the hinge was made from the 30 by 30mm square welded strait to the lid. The welding was a pain. The steel from the lid is so ridiculously thin, I kept burning holes. If I ever make changes on the lid, I will definitely rivet or bolt this. Now I only had to drill some holes to bolt in the air spring saved from a washing machine and the lid as finished.

The one thing that makes the ceramic BBQ so good is the fact ceramics doesn’t conduct heat very well, so there is a hotter and more constant temperature inside. But of course, this can be improved.

Since stone wool building isolation is totally nonflammable ,heat resistant, and a much better insulator, this makes a big improvement on the ceramics. Only problem is it doesn’t look very good. But this can be easily fixed.

I placed the bottom side of the BBQ upside down on a Lazy Susan. Just a Regular one from Ikea. Was of course to small, so I cut a piece of plywood in a circle, and clamped it on top. This way the whole egg could be easily turned, like how they use to make pottery. This realy helps getting the egg round.

I glued the stone wool around the entire surface of the BBQ with a cement-based tile glue. Then wrapped the whole in Alu foil, since this is a good reflector for radiant heat. To make sure this all stays in place I wrapped some 1mm steel binding wire around the BBQ. Also, for extra, some glass fiber mesh, The kind the use for the seams in drywall. And then the sticky part begins.

Still on the lazy Susan, The whole surface of the bottom part is then covered with plaster, just the same stuff people use to make the walls strait. Only make sure you use a type which is suited for tiling. I only made it much more wet, and kept on rubbing in glass fiber I pulled from a glass fiber blanked. I kept on applying plaster and glass fiber till there was an even layer of 1 cm around the whole bottom part. Let this dry overnight.

For the lid I wanted to be sure it fitted the bottom. So I made the last layer of plaster while it was in place on top of the BBQ. I placed a ring of cardboard on the bottom part and placed the lid. Gave the lid the same layers of stone wool, Alu foil glass fiber mesh and plaster with the glass fibers, and lit this dry again overnight. Now it really starts looking like an egg.

The next day I sanded of some irregularities, and it was time to make it beautiful.

Started with the bottom part, placed on the Lazy Susan again, and started to stick the tiles on with a cement-based glue. Tiles are 15 by 15 mm glued on a mesh to a total sheet of 300 by 300mm. Since the whole thing is round you can’t stick the whole sheets on at once. So they have to be cut to smaller strips. For the straight parts I used strips of 8 or 6 tiles wide, going to, for the really round parts to strips of only one wide.

When the bottom part was finished, I turned it around and placed it on its wheels. Put the lid on top and continued tiling till the whole surface was covered. I let the glue dry overnight and the next morning it was time to fill the tiles joints. This was a really nice moment, really happy with how it looked.

I was a bit worried that because steel gets bigger when it’s getting hot the whole thing would crack, so I decided to make a small gap between the plaster and the steel with a thin hacksaw. Since the plaster wasn’t still totally dry this was easily done. Then off to the shop for a nice piece of rib-eye and the testing may begin.

Better than I could have hoped for, it gets with less than half of the coal I needed before, 150 degrees hotter, within 10 minutes to 400 degrees Celsius. There was a bit of a problem with air leaks trough the lid so I made a seal with silicone. Just the regular stuff for bathrooms and such. The outside of the Egg doesn’t get hot at all, just nice and warm to the touch, so no problem for the silicone.

The only downside for cooking is that, because the egg is so well insulated, the heat stays in, so it’s difficult to trim back the temp while cooking.

The hinge is a bit to wobbly, would have been better if I made it double. And I’m going to have to improve the landing gear of the egg. This is still the original one, but this was designed for the light kettle, and the egg is a bit heavier, so it would be better to have a more robust foundation. Ill fix that in the near fututure