Tanzania/Canada

[Laurentius]

Re: Tanzania/Canada

But are you paying for it? A tennis court material and an oven requirement are not the same, don't you think?

[david s]

Re: Tanzania/Canada

I totally agree, but if you can't get the recommended material and you need a substitute, then you use what you can. If the anthills are basically clay then that is a material that has been tried and true for centuries. Maybe I should not have made any reference to tennis.

[Laurentius]

Re: Tanzania/Canada

Hi David,

I'm not trying to be difficult. My point is if you are paying for it, buy brick dust, ceramic dust, something that has been fired and not a byproduct of an insect because one guy recommended it. When I was researching my oven, whenever I Googled, refractory products the first hits where either Australia or China, so you have the sources available.

[david s]

Re: Tanzania/Canada

sure, but Steve is in Africa.

[SteveS]

Re: Tanzania/Canada

I think you are right David. The Brickman actually uses this material for making his bricks. He makes many different styles of brick. To makes the bricks he uses a single stroke deisel engine attached to what looks like a large meat grinder, fills the hopper with 1 bucket of mud at a time and extrudes a line of formed mud onto a set of rollers, cuts the line with a wire tool and removes 3 bricks at a time and repeats the process. Remember the playdough tool we used to use to squeeze out star or square shaped tubes of colored dough? That is basically the process.

He then loads up to 1,200 bricks into a 8'x12'x6' high brick enclosed cavity. They are placed in rows and packed with rice husks. Once loaded the rice husks are slow burned/smoldered to 800 degrees. They are removed after about 40 days and are very hard. Most other brick makers here either sun bake or wood fire their bricks for a much shorter time resulting in a much softer brick.

Cheers, SteveS.

[cobblerdave]

Re: Tanzania/Canada

SteveS
Sounds like things are looking up for you... fired bricks....Pluimus stone for insulation and some healthy discusstion from the forum.
What does you brickman do with his mis-shaped bricks... you might be lucky and he pounds them up to put back through his Mix.....or he might have pound the original termite mound and you could ask him to pound up some regect bricks so you get some fired " fireclay" for a mix.
Either way you might make up some test mixes and put them in a fire to find out what survives?

Glod bless
Cobbler dave

PS i don't think termite clay is held together with termite Poo but termite spit

[SteveS]

Re: Tanzania/Canada

Soooo Dave....smashing up some old bricks that had been fired to 800 degrees would be my fire clay?

SteveS

[SteveS]

Re: Tanzania/Canada

Should have read your email a bit closer! The answer is clearly yes...and Yes your right! Things are looking up!

Now, the fornobravo pompeii oven plans suggest;
"These instructions show how to build a cooking floor using
firebricks. With this method, you do not mortar the bricks in
place, but rather spread a thin layer of paste made from
sand, fire clay and water as a "bed" for the floor."
My floor bricks are a bit thicker in the center running lenghtwise, so when I lay them, they will be much more wobbly then flat fire bricks. Also I am extending them outward past the 40" (to avoid cutting out a circle) and will be laying my oven coarse on top. My question is will this material be enough support or might I add a little cement and lime for stability? Also the bricks aren't perfectly square resulting in some 1/4 inch gaps between the floor bricks in areas. Should I put something in mixture in there or will it eventually fill up with ash debris from firing the oven?

Thanks again for everyones timely responses!
SteveS

[dmun]

Re: Tanzania/Canada

I don't know on this one. We had a builder who laid his floor on the clay/sand mixture, but he was using repurposed tapered firebricks so the leveling mixture was greatly uneven, and his floor bricks buckled in use.

That said, if your bricks are just a little wobbly, the leveling mixture should work fine. You're not trying to hold up one end in the air.

As for the gaps between bricks, I think wood ash will fill them.

[cobblerdave]

Re: Tanzania/Canada

SteveS
Why dont you make up some mixes to see what produces a fire-resistant mortar. Use the homebrew fire mortar mix in the Forno instruction...
sand lime cement powder and crushed fired brick dust in the place of "fireclay".
Then make one with the plain termite mound in the place of the "fireclay" Finally make one using only lime cement and sand (this will be you stardard to check the other two samples against)
Then build a good hot fire and cook your samples to see what works. The materials are definitly a local product that only you can test.
Yery interested to see the results they may not be that scientific but the heck.... your in the middle of africa you have got to use what you can get don't you

Regards
Cobbler dave

[SteveS]

Re: Tanzania/Canada

Just curious, do the floor bricks HAVE to be pasted down with the mixture as indicated in the plans? I have the floor perfectly level with all the wobbles gone now without the clay and sand mixture. Also the 8" for the vent landing seems likes a very short distance to fit the chimmney into.





Really dirty and tired SteveS.

[cobblerdave]

Re: Tanzania/Canada

Dear SteveS
Now am I right your Hearth bricks are layed on a layer of crushed plumius stone? right? If so you dont need the fireclay mix as well its only to level the hearth bricks on a Cast surface IE Pearlite cement.
Now the depth of the entrance to the oven to the dome I used 1 and 1/2 stardard bricks... forget that... none standard bricks. Measured my oven entrance ( hope you appreciate this as its pouring rain) 350 mm or 14 ins. I recon any deeper and it makes it harder to use the oven as you have to pass everthing down a big long tunnel.

By the way IT LOOKS GREAT!!!! you must be pleased with the progress

Regards
Cobbler dave

[dmun]

Re: Tanzania/Canada

ust curious, do the floor bricks HAVE to be pasted down with the mixture as indicated in the plans? I have the floor perfectly level with all the wobbles gone now without the clay and sand mixture.

Nope, if it's flat, you're done. I used insulation boards, and my floor just sits on them.

[SteveS]

Re: Tanzania/Canada

Thanks Dave and dmun,

Yes, I do appreciate that Dave. It felt like I was on Mars here yesterday so if you could send a little aqua-relief this way, that would be great! Not too much though, since the rainy season here is just around the corner!

For my insulating layer I decided to go with a layer of the cheap, cheap, solid blocks (4"x9"x18") laid flat and lightly cement to the hearth. They are made of 11 parts pumice, 3 parts sand and 1 part cement. They are so light that I can pick up one of these monsters with one hand. They should have plenty of air pockets in them for good insulation.

I was thinking of filling in those holes in my floor bricks with dry fine sand (see earlier photo of brick). I thought that that would retain the floor heat better than 3 long air spaces per brick. Also my chimney will be rectangular and have to be brick. I will fabricate the base of the rectangle out of angle iron. What would the optimum flue dimension be for a 40" oven?

The dome bricks that I am using are 11 inches long. I am going to cut them in half for my first upright coarse. Thinking I should cut them on a bit of an angle so my second flat coarse will start on more of a correct angle toward the top of the dome.

Also is there a way to duplicate my thread over to oven construction. Probably should have started it there in the first place? My thinking is I might get a few more views leading to more usefull tips or ideas from forum followers.

Cheers, SteveS.

[cobblerdave]

Re: Tanzania/Canada

dear SteveS
as a good friend of mine said I a bit "masonary impaired" so a square opening is what I built supported by angle iron as well
attached are a couple of photos which might help.... a picture is worth a thousand words
construction

and completed


As you can see the chimney size is dictated by the oven opening size (check the instructions for yours). Make sure you leave a revel, a lip around the opening, so an oven door can be fitted to seal off the oven.
From memory the chimney ended up about 4 bricks wide 2 deep and is 5 bricks higher than the top of the oven door. The slot that carries the smoke is as wide as the oven door one brick thick. It draws well and handles the volume of smoke easily. I kept its height low so it would not be to heavy, any higher and I would have continued with a metal flue.
hope this helps
Regards cobbler dave