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Steel Dome Oven - Forno Bravo Forum: The Wood-Fired Oven Community

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Steel Dome Oven

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  • Wiley
    replied
    Re: Steel Dome Oven

    Peter,
    Thanks for your thoughts :-)

    My plan (subject to change, of course) is to cover the dome with a layer of aluminum foil. The refractory will be a concrete mixture using calcium aluminate cement and crushed basalt. The plan is for this to be mixed in small batches and hand packed upon the dome in a somewhat orderly fashion, but with definite expansion joints (probably with aluminum foil) between "blocks" of the refractory. My calculations put the expansion of the dome at less than 1/4 inch, that's radius of the sphere, for a 800 degree F differential. But the idea is the refractory can expand and contract and nothing will fall out and into the pizza. The loss from the lack of refractory where the cracks form will, I expect, be minimal, and the steel will "bridge" the cracks making for a uniform radiant surface. And when it cools it all shrinks back together.

    The expansion of the whole will hopefully be allowed by a layer of Frax (insulating blanket) which covers the refractory. Over that will come the vermicrete and over that the stucco. If that fails and I get cracks on the outside of the dome, then I will turn to a rectangular "house" over the dome with the loose vermiculite etc. That is not my first choice I prefer the curves of the dome/igloo shape.

    Wiley

    And here's a photo of the entrance with the bottom ring ground to the height of a standard refractory brick.

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  • PeterW
    replied
    Re: Steel Dome Oven

    I've been watching this with interest, and I'm really impressed with the re-use of old stuff...!

    One think I did think, is expansion of the steel. This might sound an odd suggestion, but why don't you add a thin layer of a compressible fibre insulation, such as 10mm of rockwool before the outer refractory..? It will allow the steel to expand but not crack the casing..?

    Just my 2p

    Cheers

    Peter

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  • Wiley
    replied
    Re: Steel Dome Oven Update

    I got a few days off and managed to get some work done on the WFO and figured I should post an update as to progress. Attached are some photos:

    First shows the entrance (half split rim) welded onto the dome. View is from the top. Photo is out of order date wise as the original got lost somewhere's.

    Second shows the dome inverted and ready to cut out the entrance itself. Entrance was welded to the dome before any cutting to minimize distortion of the dome from the welding.

    Third shows the back weld of the inside of the entrance. Entrance had to be cut before back welding in order to weld to the edge of the dome.

    Fourth shows the weld but ground and sanded to make for smooth flow of hot gasses in exiting the dome.

    Fifth shows setting the dome back into the shop. It's easy with the right tools, in this case an excavator :-)

    Next I'll grind the bottom of the entrance to the height of a standard firebrick and then build the transition/support piece to the chimney.

    In order to slow the heat transfer from the steel dome to the front of the entrance I am planning on cutting the entrance so that it is essentially two arches. When finally assembled the outer arch will be spaced about one inch away from the arch that is welded to the dome. That space will be filled with insulating refractory. This is for safety, otherwise I can imagine the outer edge of the entrance getting quite hot.

    If all goes well, I should be able to "test fire" the dome in a week or so to be sure it draws and (if necessary) make modifications before cladding the dome with refractory and setting on the platform... which I haven't built yet :-)

    Wiley

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