Re: Portable Oven Designs
cvdukes,
Actually I got the dome as part of a trade from our local scrap metal guy. He has a contract to cut up old propane spheres and tanks for recycle. He had the half dome and another full sphere one time when I was in dropping stuff off and they looked cool and we worked out a trade. The half dome is only 40" in diameter the other is much larger closer to 48".
As for thermal expansion I was thinking along the lines of a product our local quarry sells called "1/4 minus" for covering the dome itself. It's basically finely crushed basalt, they use it for top dressing on walkways and drives. It packs down quite well and I figured I could mix a bit of Fundu ciment as binder and basically "dry pack" the thermal mass layer. Perhaps creating deliberate score lines for "controlled cracking". I read where it is recommended to cover the bricks in conventional brick ovens with aluminum foil to allow movement. I was thinking doing this over the steel hemisphere. That it gets bigger and smaller shouldn't be a problem if that movement doesn't effect the weather resistant outer skin. I was even thinking at one point of simply cutting the larger sphere in two and using it over the other sphere with 3" of basalt pack and 1" of Frax. From what you'all are indicating that may have enough thermal mass for pizza and perhaps some bread too? Perhaps I could save on the cost of Frax and simply fill the extra space with dry vermiculite poured in thru a hole in the top?
I came across a company called "Pivot" located in Australia that makes ovens that are basically two hemispheres (one inside the other with a couple inches spacing) and which they fill that space with sand. Seems to me that without insulation it would cool down fast and when hot be pretty dangerous as in "Don't lean on that!!!"
Thanks one and all for your input. I'm not totally locked into using the hemisphere this way. I was even thinking one could use it as a "plug" in the manner some boats are built. Cast the refractory dome in sections over the top of the steel hemisphere and then remove and reassemble the cast pieces. Then there would be the chance of spalling, right? anybody cast their dome?
thanks,
Wiley
cvdukes,
Actually I got the dome as part of a trade from our local scrap metal guy. He has a contract to cut up old propane spheres and tanks for recycle. He had the half dome and another full sphere one time when I was in dropping stuff off and they looked cool and we worked out a trade. The half dome is only 40" in diameter the other is much larger closer to 48".
As for thermal expansion I was thinking along the lines of a product our local quarry sells called "1/4 minus" for covering the dome itself. It's basically finely crushed basalt, they use it for top dressing on walkways and drives. It packs down quite well and I figured I could mix a bit of Fundu ciment as binder and basically "dry pack" the thermal mass layer. Perhaps creating deliberate score lines for "controlled cracking". I read where it is recommended to cover the bricks in conventional brick ovens with aluminum foil to allow movement. I was thinking doing this over the steel hemisphere. That it gets bigger and smaller shouldn't be a problem if that movement doesn't effect the weather resistant outer skin. I was even thinking at one point of simply cutting the larger sphere in two and using it over the other sphere with 3" of basalt pack and 1" of Frax. From what you'all are indicating that may have enough thermal mass for pizza and perhaps some bread too? Perhaps I could save on the cost of Frax and simply fill the extra space with dry vermiculite poured in thru a hole in the top?
I came across a company called "Pivot" located in Australia that makes ovens that are basically two hemispheres (one inside the other with a couple inches spacing) and which they fill that space with sand. Seems to me that without insulation it would cool down fast and when hot be pretty dangerous as in "Don't lean on that!!!"
Thanks one and all for your input. I'm not totally locked into using the hemisphere this way. I was even thinking one could use it as a "plug" in the manner some boats are built. Cast the refractory dome in sections over the top of the steel hemisphere and then remove and reassemble the cast pieces. Then there would be the chance of spalling, right? anybody cast their dome?
thanks,
Wiley
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