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Planning my 32" cast oven

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  • #31
    Originally posted by AndreasP View Post
    Gulf , Of course, you are absolutely correct, not sure how what i was thinking.

    I updated the layout (more so that I know how many bricks to buy).

    If I counted correctly the left layout requires one less brick (31 bricks, not that it matters) vs. the one on the right, because I can cheat a bit using a cutoff for the bottom left most brick technically not quite in the pattern.

    I still think I will go with the one to the right. I kind of like the look at the entrance a bit better I think.
    I went with the one on the left, no real reason, don't think it will matter much. I also tried to put the nicest bricks in front and the lesser ones at the back for aesthetics, but really once your oven is functional you will never look at the bricks again, so just go with your gut feeling
    My 70cm (28") build: https://community.fornobravo.com/for...losure-belgium

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    • #32
      Yes, I will pick the best bricks, probably for the front and center and pick the others for around the edge and to be cut.
      i just got my bricks. Initially i picked the HC Music, but they are low duty (21% Alumina) and their sides are rather wavy.
      I found Smithfield Unbranded Med Duty (30.8% Alumina) still low duty according to Forno Bravo Brick Primer, but that's the best I can find. And, the sides are super straight.
      Also found vermiculite, A3 grade. Should be all set for material, just waiting for the Foam Glass to be delivered.
      Last edited by AndreasP; 10-06-2021, 07:39 AM.
      My oven build thread https://community.fornobravo.com/for...y-32-cast-oven

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      • #33
        Finally have all the material and am trying to figure out how to make sure moisture does not get into the insulation. Attached is what I am planning. Any feedback is appreciated.

        Floor:
        • 3/8" ceramic tiles, just because it adds a bit more space below the Foamglass and lifts it up a bit. I can live with a bit more height
        • 2" Foamglass
        • 2" CalSil
        • 2 1/2" Firebrick
        I am planning on having the Foamglass extend as far out as possible, so that it can keep everything off the damp concrete. My concrete pad is directly on the ground in a hillside

        Finishing around the oven
        • I am planning on casting a concrete countertop at some point. It will integrate the area around the oven with my outdoor kitchen. I wanted to make sure the top of the countertop is below the top of the foamglass, so that any water that may get through the render stays below the CalSil. I only have a 3/8" height difference in the below design. I am considering making a thinner countertop around the oven, but then I would have a transition of let's say 1/2" or so between the outdoor kitchen and the area around the pizza oven
        • Alternatively I could pour a bit more concrete where the oven goes (or use two layers of 3/8" tile) to lift it a bit more, but that seems to be a lot of effort for possibly not much gain.
          Any thoughts or suggestions?
        Dome:
        I think the dome is pretty standard. As I have mentioned before, I have very limited space, so I will try to use all the Ceramic Blanket I have (3") and only use 1" of Vcrete to recover to the rounded shape. I will see how it goes.

        Click image for larger version

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        My oven build thread https://community.fornobravo.com/for...y-32-cast-oven

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        • #34
          Made some more progress today. I was able to cut all of the insulation. Cutting the bricks next weekend and hopefully casting the dome.
          Last edited by AndreasP; 10-18-2021, 04:37 PM.
          My oven build thread https://community.fornobravo.com/for...y-32-cast-oven

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          • #35
            Very nice. You are using almost the same insulation sequence as I did on my cast oven. Once cured, the outside of my oven stabilizes at ~100F when the inside is ~900F for pizza. A breather valve at the top of the dome (I used a crankcase breather cap) plus a horizontal vent that exits into the chimney to provide water vapor escape paths when the oven is fired.
            My 32" homebrew cast oven by the sea

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            • #36
              CoastalPizza , thanks for the reassuring comment. Yes, I am planning on using some form of venting system. I am only planning a vent at the top of the dome. I looked at your build thread. Did you simply install the second vent so that it opens into the gallery of the oven below the chimney? Are you plugging the vents when you are not using the oven to avoid moisture from entering the insulation?
              We are fairly close to the ocean and often have 99% humidity in the early morning.
              My oven build thread https://community.fornobravo.com/for...y-32-cast-oven

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              • #37
                ​Trying to plan the form for the dome opening to get ready for casting the dome this weekend. I am thinking of doing an opening to the dome that is somewhat rectangular with a curved top. I think this will give me more space to place items into the dome.

                For reference:
                • Dome diameter - 32"
                • Dome height - 16"
                Opening to in the cast dome:
                • Width 19" (is that too wide for this size dome?
                • total height 10" (62% of dome height)
                  • height of the rectangular section 8"
                  • height of the curved top in the middle 2"
                I am wondering if this design makes sense or if there are any issues with this. To interface the cast dome to the shape of the opening I will have to go away from the completely circular shape of the dome when it goes towards the opening.
                am thinking of just using some pink foam insulation panels to create the form.

                Click image for larger version

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                My oven build thread https://community.fornobravo.com/for...y-32-cast-oven

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                • #38
                  Not sure why the image is so small in the post. I will attach it to this post. The file on my computer is 1600 x 1024 pixels and 500kB.
                  My oven build thread https://community.fornobravo.com/for...y-32-cast-oven

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                  • #39
                    "Did you simply install the second vent so that it opens into the gallery of the oven below the chimney? Are you plugging the vents when you are not using the oven to avoid moisture from entering the insulation?"
                    Yes, that is exactly what I did. I used a well greased piece of PVC pipe (~1" dia.) inserted into the fiber insulation when I added the perlcrete and cast my inner arch. The pipe was pulled before casting the rest of the chimney gallery. That vent exits in the gallery below the chimney and is tilted down so rain will never flow into the insulation.

                    "We are fairly close to the ocean and often have 99% humidity in the early morning."
                    Same here -- the oven is about ~100' from the Intracoastal Waterway and about 1.5 mi. north of Bogue Inlet. I have a removable cover that goes onto the chimney plus a tilted-outward door in the arch that minimize rain getting into the oven. The vent at the top of the dome is plugged with a crankcase breather cap. I have found that I need to fire the oven early in the day to dry it out if it has been particularly wet. It takes me a couple of days of progressively hotter fires after a real dumper like the 34" of rain and 100 MPH wind we got during hurricane Florence in 2018.
                    My 32" homebrew cast oven by the sea

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                    • #40
                      CoastalPizza, thanks for your response. Luckily we don't often get rain storms like that in Southern California. I am more worried about several months of 99% humidity at night ant 70% during the day. Then again, the oven will be in the sun, so that should help drying it out.
                      I am planning on making some kind of cover for the complete oven, like a BBQ cover. Not sure yet where to get the material, but I am sure I can figure something out.
                      My oven build thread https://community.fornobravo.com/for...y-32-cast-oven

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                      • #41
                        Re the door opening size… I think 17” is a more standard size for a 32” dome whether or not a 19” opening will make much difference I cant say.
                        You will loose a bit of mass and it may look slightly out of proportion and there may be some form of performance diference compared to a 17” opening but it has been mentioned on this forum that the opening width can be variable size…. However I dont know how much actual testing has been done?

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                        • #42
                          Fox, thanks for your feedback. Yes, I am struggling a bit with deciding on the "perfect" door opening size. I have looked through the forum and it seems that different people used openings between 17" and 19". I also looked at some of the commercial ovens to see what people are doing.
                          One of my challenges is that the oven is in a corner, so I think a larger opening will make it easier to access the inside (I have no access from the "hill" side), but I don't want to compromise performance.

                          Here is a table of what I think found:
                          oven internal diameter door width door height door recess
                          Mullster 32 18 10
                          Ronstarch 29 17
                          Kris S 28 19
                          Sergetania 30 19
                          Nick JC 32 17.7 9.86
                          Melbourne fire brick company 33.5 17.7 10.4 0.8
                          Brickwoodovens Cupola 28 28 18 8 side

                          10 middle
                          1.5
                          Brickwoodovens 36 18 8 side

                          10 middle
                          1.5
                          Forno Bravo Casa 32 32 17 10 center 1.5
                          My oven build thread https://community.fornobravo.com/for...y-32-cast-oven

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                          • #43
                            Finihsed cutting and laying down the insulation. Had to redo some of the cuts. It seems that the string i used to draw the circles was a bit too elastic. Circles ended up not being circular and about an inch to large in diameter.

                            Redrew all my templates using a stick, nail and hole for the pencil. Much better results.

                            On to cutting bricks and building the sand castle. Hopefully casting tomorrow.
                            My oven build thread https://community.fornobravo.com/for...y-32-cast-oven

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                            • #44
                              Trammel Points

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                              • #45
                                Had to look it up, I guess technically it's a beam compass. the nail and pencil are the trammel points. I didn't know one can actually buy the trammel points. Here is a link to a video with Adam Savage. Might help some others.
                                 
                                My oven build thread https://community.fornobravo.com/for...y-32-cast-oven

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