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Alan Scott oven project begins

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  • UtahBeehiver
    replied
    Moved to Other Oven Types

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  • astroinfidel
    replied
    Some of the pics between this post and the above one are out of order and I can't seem to fix that. The first pic here is just a dry fit, but it gives an idea of the shape of the front of the oven and chimney. The chimney will be faced with the granite as well. I will paint the steel with heat paint tomorrow and hopefully have the Flintstone slab in place the next day. Then I can start on the chimney.

    Dean
    Last edited by astroinfidel; 09-07-2019, 05:54 PM.

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  • astroinfidel
    replied
    Hi everybody,

    Here are some recent pics from my oven build. The concrete cladding is poured, and I am currently working on the outer hearth. I decided to replace the Flintstone slab spanning the entryway with one that matches better. The last few pics are from today as I cut it and notched it for the steel. The granite and steel expand at different rates, and granite cracks easier than most stone under heat, so I will be using aluminum foil between the steel and granite when I set them in mortar so the are independent of each other. The steel will make any cracking of the granite Flintstone slab a cosmetic issue only. This slab has to support not only its own weight, but also the weight of the front of the chimney, so the steel will make sure it has the strength it needs to do so even if it cracks.


    Moderator: I guess I should have started this oven build post in the section on brick ovens, rather than here in introductions. Is there any way to move it to the appropriate section of the forum?

    Dean
    Last edited by astroinfidel; 09-07-2019, 05:54 PM.

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  • astroinfidel
    replied
    Hi David and Russell,

    Well you guys have convinced me to brace the soldier course...see pic. As for the perceived weakness of the oven design, it doesn't seem to prove to be deficient in actual use. I have not heard of any Alan Scott ovens having problems in the areas that you describe. I wonder if the fact that the hearth fire bricks are not mortared into place helps? It would for example allow the back wall to move slightly if pushed by the expanding oven when heated. Sort of a built in stress relief?
    I will leave the bracing on the walls for the next week or two until I encase the entire oven in a few inches of concrete. The soldiers won't be going anywhere after that.

    Dean
    Last edited by astroinfidel; 09-07-2019, 04:47 PM.

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  • david s
    replied
    I guess if you are following the Alan Scott plans then the design has been tested. However if this were a kiln it has a number of design weaknesses. It is an oven and subject to around half the temperature and therefore thermal expansion of a kiln. But the structural integrity is compromised by having long vertical joints in the soldier course. The back wall appears to be built beside rather than under the vault and therefore subjected to the expanding vault wanting to push it out. The vault bricks are not laid on bond which weakens the vault. These issues can be addressed with either buttressing or bracing. You may get away with not doing either, but the long term use will test the structure from the constant heat cycling. If you were to fire the oven daily any problems are likely to occur sooner than if the oven only gets occasional use.

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  • astroinfidel
    replied
    Russell I think Alan Scott often built these ovens in seminars and had 6 or 8 people working on them at once. I could imagine the arches being started the same day the soldiers were laid, or the next day. So I could understand it then. There is a point in this build where the bracing would have to come off anyway, and a period of time would go by before they were encased in concrete and secured. So they must be able to take the pressure if the soldiers are not too freshly set.
    I wish I knew how to figure how much of the load per arch is downward, and how much is sideways on the soldiers. I figure each arch is about 100 lbs. If half that weight is pushing outward..horizontal...that means of that 50 lbs there will be about 25 lbs per side, split between 4 soldiers. That is just over 6 lbs per soldier. And I bet the sideways loading is much less than 50%.

    And I won't be adding much heat to the oven until it has been encased in concrete in a few weeks. I will likely use a propane space heater to dry the oven before pouring the concrete cladding, but I won't let it get too hot.

    Dean

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  • UtahBeehiver
    replied
    Hope you are right, when you add heat to the equation and you start to get expansion and contraction going on there is going to some movement. Right now the oven is at a static ambient temperature. I guess the Alan Scott plans suggested buttressing for a reason.

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  • astroinfidel
    replied
    Russell I was going to brace the soldiers as per the plans, but recently decided not to. I recently saw a build online of a guy that didn't without problems. And I tried to knock a joint loose on the soldiers with a brick set 2 days after laying the bricks, and it wouldn't break after 3 good hits. They soldiers had been up a week or two when I started the walls, and I think they are tied in well enough to not need it. The whole thing is going to be covered in a few inches of concrete soon, and that will brace the walls for the long term.

    I got the second arch done today. Here are a few pics. And I am striving for zero mortar on the arch joints inside. Not always achieving it, but it keeps them small when I don't.

    Dean

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  • UtahBeehiver
    replied
    Nice tight inner joints. Due to the low dome configuration and full soldiers on side wall, are you going to buttress the soldiers. The low dome shape will have quite a bit of horizontal load at the dome and soldier joint.

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  • astroinfidel
    replied
    Checking to make sure the peel won't snag a high spot on the hearth bricks. Cleaning excess mortar, and a look at the inside of the first arch. I will finish the second arch tomorrow afternoon.
    Dean
    Last edited by astroinfidel; 07-23-2019, 11:17 PM.

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  • astroinfidel
    replied
    Here are the latest pics from my oven build. I removed the heath slab forms, and have started the vaulted roof. I'll attach more pics in another message.
    Dean

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  • astroinfidel
    replied
    Got it! Thanks Russell! Wow that is a long time to dry. I will be very careful drying the slab when I eventually fire it up. That is going to be a while yet though. I got a few more bricks in the wall today. Here are a few pics. The Heat Stop 50 is so nice to work with. It spreads like peanut butter and clings like glue to the bricks. It is so expensive that I only mix up enough for a few bricks at a time. I will hopefully finish the back wall tomorrow.
    Dean

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  • UtahBeehiver
    replied
    I "snipped" and converted DavidS vermculite study to a jpeg file and attached.

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  • david s
    replied
    Apologies, I think it may be that my Microsoft Office is out of date and it won't let me export docs. I'm feeding it money, hope that will fix it. Get back to you in a few days.

    While i'm here this thread of an Alan Scott oven should be of interest to you.
    #1
    Last edited by david s; 07-14-2019, 03:27 AM.

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  • astroinfidel
    replied
    David it opens as code..gibberish to this code Luddite. I tried notepad and Explorer to open it with the same results.

    Here are a few pics of the beginning of the walls this afternoon. The Heat Stop 50 is actually very nice stuff to work with. I laid the first 4 angled bricks horizontally on the top of the foundation wall. I let them set up, then turned them 90 degrees and laid the 4 bricks as one big brick. I was going to use that method for all the walls, to avoid having to try to butter the vertical surfaces. But the Heat Stop 50 sticks so nicely to the vertical brick faces that even a rookie like me has no trouble buttering them. So I will do the rest of the wall bricks one at a time using a line as in the pic.

    Dean

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