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Please help???? Possible problem in my design. - Forno Bravo Forum: The Wood-Fired Oven Community

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Please help???? Possible problem in my design.

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  • Please help???? Possible problem in my design.

    So I might have a problem that I may need to correct before I go any further. I was hoping to get some advice from the community. It was pointed out to me that my inner arch is too far out and could cause it to push outward from the weight/pressure of the rings. Can anyone comment on this?

    Thanks a bunch,
    Tim
    Attached Files

  • #2
    Re: Please help???? Possible problem in my design.

    I don't think it will be a problem. In fact, the vault (dome) shape at the inner arch is closer to a catenary arch than the rest of the dome. A large number of builders have experienced this and some choose to gradually bring the dome back into round, others not. It doesn't really affect the performance of the oven.
    John

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    • #3
      Re: Please help???? Possible problem in my design.

      John, you don't think this will cause structural problems?

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      • #4
        Re: Please help???? Possible problem in my design.

        It shouldn't be a problem, you should add some buttressing to arch though.

        Comment


        • #5
          Re: Please help???? Possible problem in my design.

          No. You have no idea how many ovens I've seen on the FB site that look exactly like yours. I haven't heard any complaints of dome failure from oval or teardrop-shaped domes.

          Comment


          • #6
            Re: Please help???? Possible problem in my design.

            Thanks for the info. Makes me feel a lot better about things. You don't know the stress this kind of thing can cause.

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            • #7
              Re: Please help???? Possible problem in my design.

              Tim
              Makes me feel a lot better about things. You don't know the stress this kind of thing can cause.
              Sorry about that Tim. Now I feel bad for raising what appears to be a red herring - it was not my intention to cause any stress - and I am glad that the consensus seems to be that the structure is sound.

              John (Gianni)
              I haven't heard any complaints of dome failure from oval or teardrop-shaped domes.
              Just to be clear I didn't ever think the oval or teardrop shape is a problem. I was just under the (mistaken) impression that the arch attachment to the dome should either be of the "V" type (dome bricks wrapped around the arch bricks) or the angled type such as you, I and others adopted.
              Aidan
              Amac
              Link to my WFO build

              Comment


              • #8
                Re: Please help???? Possible problem in my design.

                -So I see a different problem (sorry and I am just trying to help). But in the first picture you can see that your bricks don't rest on top of the arch, they just run/butt up next to it. I don't know if this is a problem, but they are not supported by the arch (at least not very well).

                -With more weight on top of them I don't know how they will hold up.

                -I have a slight teardrop shape to my dome but I was very careful of staying over the arch until I got over it and then made my correction.

                -Then, how does it look when you remove the wooden door support to your arch? Can you see your dome bricks poking out?

                Good luck (can any one see what I am talking about?)

                Mike D

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                • #9
                  Re: Please help???? Possible problem in my design.

                  It looks like he beavertailed the dome a bit, but it's not critical. Remember that the thrust of the dome is downward and inward--the dome is literally collapsing in on itself toward the center of the oven, and that load is ideally transferred down along the cantenary curve. Once he adds the next course, the dome will be locked into the arch and the downward thrust will be transferred into the dome entry arch in that area. There's very little lateral shear being pushed into his arch, and the mass of the arch, landing, vent, and chimney will counteract it.

                  Comment


                  • #10
                    Re: Please help???? Possible problem in my design.

                    Mike D
                    But in the first picture you can see that your bricks don't rest on top of the arch, they just run/butt up next to it. I don't know if this is a problem, but they are not supported by the arch ...
                    If you look at my original post this is the exact point I was trying to make in tagertims original thread - obviously not very well - since it was taken to be a criticism of the oval/teardrop shape. Note to self: "be more careful with phrasing"
                    I thought that at heating up the dome would tend to push the arch outward but azatty seems to have answered the point pretty well though. Also I think the entry when it is complete will act as a buttress in that direction.
                    Amac
                    Link to my WFO build

                    Comment


                    • #11
                      Re: Please help???? Possible problem in my design.

                      I was able to get the three bricks against the arch to rest on the arch hoping this will help to support them. When I take the form for the arch off I will post more pictures.

                      Tim
                      Attached Files

                      Comment


                      • #12
                        Re: Please help???? Possible problem in my design.

                        Tim, I agree that you should not have any structural problems. With that tear drop shape you will find that it will get more challenging as the chains go up. So you will need to do more custom fitting as you start to close things up. My advice it to take your time relax and go with the flow from this point on. I have seen this on other ovens and there comes a point that you can see the builder had a meltdown and you get that thrown together look just to get it done. From what I have seen so far I think you should do fine.

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                        • #13
                          Re: Please help???? Possible problem in my design.

                          Thanks for the thoughts. Not sure what I am going to do yet. Will keep you posted.

                          Tim

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                          • #14
                            Re: Please help???? Possible problem in my design.

                            The fix for the beavertail isn't too difficult, but it takes some extra effort. Instead of half bricks, cut the bricks to 3/4-ish length. Set one end of the brick about halfway onto the arch, which is probably about where it would be if you didn't have the beavertail. You may have to cut the end to "key" it into the arch. The chamber-side of the brick will be hanging over the course below significantly. Make sure to dry-fit the brick as if it is in a circular course instead of a beavertailed course.

                            Bevel (cut an angle) the edge of the brick facing the inside of the dome. The bottom of the angled cut should be about even with the course of bricks below it. The upper edge of the cut will cantilever out over the dome. Repeat for all the bricks in the afflicted area, then switch to normal cuts once you're past the beavertailed section. You can spread the fix over a couple courses so the beveled bricks don't have such a steep angle on them. As long as you set the beveled bricks in a circle, your dome will be trued up quickly.

                            I'll post a picture if I can find one.

                            EDIT: It appears you aren't using a dome gauge. It would be helpful to use a string or other measuring device as you fix the 'tail. Measure to the back of the course first, and that will show you where the cantilevered bricks should be. You also need to do the fix now while you have relatively shallow angles on your dome courses. Once you go vertical, it's harder to fix.
                            Last edited by azatty; 05-16-2012, 08:10 PM.

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                            • #15
                              Re: Please help???? Possible problem in my design.

                              Thanks Azatty, that was helpful. Plan to work on it this weekend.

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