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Record of my 32" Homebrew cast oven, on a brick base - West Midlands, UK

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  • It looked ok. There is an overriding principle with casting and that is to provide a release. This means instead of having straight sides the mould form should be made so there is a slight angle, maybe only one degree. An example of this is a bucket with a slight conical form. Of course a sand mould doesn’t need this requirement because the sand can be easily removed. Polystyrene is also easily removed. Providing a release from the mould form is actually more important than the application of a release agent like oil.

    There’s nothing worse than not being able to separate the casting from the mould.
    Last edited by david s; 08-05-2020, 06:06 PM.
    Kindled with zeal and fired with passion.

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    • I learned that. The mold was made of polystyrene but I had to use a forstner bit to drill it out. Good thing it was polystyrene.

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      • Nick J C quick question - once you had finished the final render cost and removed the card around the flue - you must have had a ~5mm gap - what have you done about that? Some sort of sealant? I know your oven is covered (and I plan for mine to be too) but I assume we still need to prevent moisture getting in that gap?
        My cast oven build thread

        https://community.fornobravo.com/for...-castable-dome

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        • Silicone. I used high temp silicone as I happened to have some , but standard stuff takes fairly high temperature . Both will melt if you allow flames into the flue, but should be fine if you are careful. My flue gets to around 150c at the point of exit, although bear in mind it has a fairly tall outlet

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          • Slowly progressing on roof, as real work and children demands..... decided to try to tile up close to the flue, and probably silicone it in to finish, rather than flash it in lead but will see how it looks when it is all bedded in
            Last edited by Nick J C; 08-18-2020, 10:50 AM.

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            • Laying ridge tiles

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              • Nick J C Hi and I hope you're well! I am just about to have a go at a door and I wondered if you could help m with a few questions please? I am hoping to make something like your's, as it looks effective and hopefully, fairly simple.

                Did you leave a small gap for expansion? I wondered which, between the door and the oven expanded and therefore, if a gap is even necessary.
                How has the design held out? - anything you would change?
                What mix ratio did you use for the V.Crete and did you reinforce it?

                Thanks again for all the previous help and in advance, if you get a chance to answer some of the above.

                Although I am still looking back, thinking I could have made a better job of certain elements, I am really happy with the oven overall and honestly, your build thread has been instrumental in getting me over the live, so cheers!

                Tony.

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                • Hi TonyPizza. Pretty happy with my door, although I am sure it won't last forever. I used cement board cut to about 5mm smaller than the opening all around, which sits against the flange, with glass fibre stove rope all around to make a reasonable seal. I put some aluminium channel on the edge to stop it chipping. The vermicrete is a reasonably rich mix of about 5:1, so insulation value sacrificed for strength, but still only warm to touch. The vermicrete layer is just smaller than the hole, and glued to the cement board with flue cement.
                  Last edited by Nick J C; 09-26-2020, 06:44 AM.

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