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Casting? - Forno Bravo Forum: The Wood-Fired Oven Community

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Dome Installation Video - Casa / Premio / Modena

Hello,

For many of you who bought a modular oven, you may have asked how we put the domes together when we build them. For those of you considering one of our ovens, we shot a video to make your install easier.

Check it out on our You Tube Channel.

https://www.youtube.com/watch?v=-7q7...jSniYogfUra06Q

If the link doesn't work, simply go to You Tube and type Forno Bravo Channel. The video title is How to Set your Forno Bravo Oven Dome Pieces.

Thanks for participating in our Forum. We will have more video content available soon.
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Casting?

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  • #16
    Re: Casting?

    Here's the money quote in that link:

    I did not use wire for my most recent castable shell and there is severe cracking — though the cracking is not structural.
    His formula seems similar to the alumina formula James gives:

    In between Refrax and fire clay/Portland cement mortar, you can make your own aluminate mortar. It is hard to work with, as calcium aluminate can be challenging. If you get the mix, or water wrong, it won't set correctly. It partially sets very quickly, and you cannot re-hydrate it, so you have to mix it and use it in small batches. Still, if you are trying to save money and want/need the heat resilience, heat conductivity and longevity of a true aluminate mortar, it works.

    1 part calcium aluminate
    3 parts sand
    1 part lime
    1 part fire clay
    It sounds like it would be difficult and unsatisfactory. If you do this, please keep us informed. We're always open to learn new techniques.
    My geodesic oven project: part 1, part 2

    Comment


    • #17
      Re: Casting?

      Lime and calcium aluminate together are not good. I've tried this and the lime acts as an accelerant to make your brew go off much faster. The calcium aluminate is also quite temperature dependant. On a cold day it takes ages to go off (use warm water) On a hot day it'll go off really fast (use chilled water or some ice) don't mix product that's been sitting in the sun. It's also quite thixotropic ie It'll start going hard but if you give it more mixing or vibration it liquifies again weird stuff.
      Kindled with zeal and fired with passion.

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      • #18
        Re: Casting?

        I'm going to try casting my vent, I think. Only thing is, I dont' know if/how to add rebar or mesh to it to strengthen. I have got a refractory mix product - I'll need 50kg of the stuff to make a 20"x14" (external) base tapering 12" up to a 14"x14" top. With those angles, casting with rebar seems awkward

        If there's only a pot on it, will it still need reinforcing? I guess I need to play with the mix to test the strengit
        Matt S, Cambs, UK
        42" Pompeii

        Pizza oven pictures - WIP!

        Pizza oven costs (so far!)

        Comment


        • #19
          Re: Casting?

          Castable refractory is traditionally reinforced by stainless needles, which you get from the same place as your mix. Rebar has such a different coefficient of expansion that I don't think it's a good idea.
          My geodesic oven project: part 1, part 2

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          • #20
            Re: Casting?

            My vent was cast without any rebar or needles and it broke upon unmolding, I still managed to mortar it back together and it works great! However, it only supports a double walled stainless flue, so if you are going to put a clay chimney pot on it, I would try to find the stainless steel needles that dmun mentions...

            Drake
            My Oven Thread:
            http://www.fornobravo.com/forum/f8/d...-oven-633.html

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            • #21
              Re: Casting?

              Hmm - the stainless needles will only be able to go vertically, though, right? It seems I need something that's going to go around in a band.

              It sounds like I'm likely to crack whatever I do though with a castable vent. Shame I'm having trouble source angle iron or I'd to that to form the vent and build up with the firebrick to a flue.
              Matt S, Cambs, UK
              42" Pompeii

              Pizza oven pictures - WIP!

              Pizza oven costs (so far!)

              Comment


              • #22
                Re: Casting?

                Angle iron shouldn't be a problem. The places that do structural steel (for the building trades) should be able to get you a piece if your hardware store can't. They call hardware stores ironmongers in the UK after all.
                My geodesic oven project: part 1, part 2

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                • #23
                  Re: Casting?

                  Well, I got my rebar from a nice but huge place that does large scale builds - they hadn't got any angle iron in stock, oddly enough. The other building places don't seem to have it either which confuses me. Now I only want a 28" section it seems more difficult to get - I can find 2m sections on ebay, not sure what I'd do with the rest of it!

                  I need to talk to some local fabricators I think!
                  Matt S, Cambs, UK
                  42" Pompeii

                  Pizza oven pictures - WIP!

                  Pizza oven costs (so far!)

                  Comment


                  • #24
                    Re: Casting?

                    S/S needles are about 1" long and form a woven matrix in all directions when mixed in your castable.

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