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28" homebrew cast oven in walled enclosure Belgium

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  • Kris S
    replied
    It seems a little more difficult to source a heat resistent glue.

    Can I just use an all purpose construction type of glue like this that should withstand 90C / 200K


    How hot could the back of a +/- 5cm / 2" hebel block glued to the multiplex board become? any idea anyone?

    what is the issue with using bolts and nuts to fix it instead of glue? would the metal transfer too much heat to the wood causing it to smolder and burn? expansion issues?

    thanks in advance.
    Last edited by UtahBeehiver; 12-10-2021, 07:22 AM. Reason: removed commercial link

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  • fox
    replied
    Click image for larger version

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    Vermiculite board, is a common product very often found inside modern wood burning stoves, it comes in lots of sizes from brick size to large sheets.
    I use it to line the back of steel wood oven doors and for lining the rocket stoves I build.
    Basically a mass produced sheet form of high temperature board made from crushed vermiculite, fire clay and waterglass, good for 1000c but not very abrasive resistant but stronger than diy V crete .
    Last edited by fox; 12-06-2021, 07:25 AM.

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  • Kris S
    replied
    Yes, I was planning on doing something similar: using heat resistant glue to attach either a shaped piece of hebel block or a poured piece of P/V-crete to a multiplex board. (saw an example of this somewhere on the forum) and then over the multiplex I can finish with some nicer pieces of wood and a handle.
    And protect the bottom with a corner piece of metal to keep the wood part of the hot entry floor.
    I don't know what a vermiculite board is, probably some commercially precast boards?

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  • fox
    replied
    You could just glue some vermiculite board to the inside of your aluminium door.

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  • Kris S
    replied
    Thinking about making an insulated door, which has better insulation properties? Do they differ much, and does it matter all that much?

    Hebel block vs. permiculite/vermiculite mix

    I guess 7 cm thick would be plenty? much better than the thin aluminum sheet I use right now?

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  • Kris S
    replied
    Originally posted by Kris S View Post
    25kg vermiculite + 25 kg perlite 35 +/- 2/3 used
    25kg bags portland cement 2 7.5
    25 kg bags sand for dome mould and homebrew 3 5
    25 kg bag fireclay 1 17
    +/- 10kg hydrated lime 0 free


    Looking back at the used materials overview from my post #102 I bought 25 kg fireclay, I don’t remember exactly how much I used but I still have some left, maybe a quarter to a third.

    I can weigh what’s left over so we know for sure, I’ll try to do that.
    Just weighed what was left of the fire clay: I used 15kg.

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  • hughesyourdaddy
    replied
    Thanks for the replies everyone.

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  • Kris S
    replied
    Just realized I haven’t uploaded a pic of the finished oven yet apparently, so here is one.
    Actually I still have some things left to do in order of importance:
    • Make a permanent chimney cap to keep rain out (the plastic bag solution is horrible)
    • Make an outer ‘storm door’ to keep rain out of the entry
    • tidy things up around the roof edges (currently just screwed a wooden board in place), don't know exactly what/how though...
    • Apply a cement render over the base
    • Paint the whole thing (better protection against rain than just a cement render)
    • Make an insulated door for longer heat retention
    • next year add a work bech / table top to the right
    Click image for larger version  Name:	20211023_132350.jpg Views:	0 Size:	283.6 KB ID:	442846
    Last edited by Kris S; 11-02-2021, 01:44 AM.

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  • Kris S
    replied
    25kg vermiculite + 25 kg perlite 35 +/- 2/3 used
    25kg bags portland cement 2 7.5
    25 kg bags sand for dome mould and homebrew 3 5
    25 kg bag fireclay 1 17
    +/- 10kg hydrated lime 0 free


    Looking back at the used materials overview from my post #102 I bought 25 kg fireclay, I don’t remember exactly how much I used but I still have some left, maybe a quarter to a third.

    I can weigh what’s left over so we know for sure, I’ll try to do that.

    Leave a comment:


  • AndreasP
    replied
    I just finished casting my 32" dome and gallery. For done and gallery I used:
    • 200 lbs of sand for the dome
      • I used some of the sand I used for the dome mould to cast the gallery a few days later, probably 30 lbs or so
    • A bit less than 50 lbs of clay - I used up the complete 50 lb bag but used a few handful in the sand to build the mould for the dome
    • Not sure on the portland cement and lime, but less than a bag each
      • maybe 2/3 of a 94 lbs bag
      • maybe 1/2 of a 50 lbs bag
    Maybe this helps.

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  • UtahBeehiver
    replied
    Look at Nick JC build, he did a really nice cast build and detailed out his materials.

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  • hughesyourdaddy
    replied
    Hi Kris,

    Great build! I'm preparing to build an oven and will use yours as inspiration because I want to build 28" too. Can you remember how much clay you used in the homebrew mix in the build? I can only source by the kilo where I am so it would be great if you could let me know. Thanks.

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  • AndreasP
    replied
    Kris, David, thanks for your feedback. I think I will stay with my original plan of a 19" opening for a 32" diameter oven. I could always stand up some firebrick along the side of the opening if I want a smaller opening.

    As far as the floor height, I have a bit of a challenge. There is a big height difference between me and my wife. I am sure I will be the one cooking in the oven, so I have chosen my elbow height for the cooking floor.

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  • david s
    replied
    I agree about the more generous oven mouth. Mine is 16” wide, but for a 21” diameter oven that’s pretty wide for a small oven, but as it’s fuel consumption is so low it’s no trouble to flash it up. Plenty of retained heat for roasts and bread etc.
    I think for working height you just get used to whatever you have.

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  • Kris S
    replied
    Hi Andreas, I went for 19” width and 8.7” height.
    If you can, I would advise choosing opening width over pondering about eventual heat loss.
    With my rather small 28” diameter oven a 19” opening is pretty large and I probably lose quite some heat, but I’m happy I didn’t go smaller than that, it would not be practical.
    19” is adequate but not luxurious, any smaller and it would annoy me I think.
    I have done pizzas, a roast chicken, pasta sauce, some vegetable casseroles, 2 breads, some bbq ribs…

    Something minor I would do different is have the oven floor higher, now the height of the floor is about 130cm I think (should remeasure to be sure), I would add 20cm to this, because I have to bend a little too much for loading and unloading. (I’m 1m87cm tall). But aesthetically I went for a little lower, should not have done that.

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