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K79 Oven Build

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  • Tscarborough
    replied
    Re: K79 Oven Build

    And that is for glass fibers, which are not normally used in mortar/concrete anymore, the alkalinity eats them up. Polypropylene fibers are more commonly used now. Coated glass fibers are expensive and will still fail.

    Leave a comment:


  • mrchipster
    replied
    Re: K79 Oven Build

    Here is something to consider with regard to adding the glass fibers

    Strain Point - 825-900 (F)
    Annealing - 875-975
    Softening - 1175-1250
    Kiln Polish-1350-1450
    Full Fuse - 1550-1600

    They go soft at temps easily seen in your oven so it i agree with Tscar they are a complete waste of effort and time.

    Depending on what type of metal you plan to use it will either oxidize in very short order or create internal stress on the structure due to the significant variation in thermal expansion between the metal and the brick and mortar.

    Have your structural engineer friends do. A simple expansion calculation for a 1000 f rise on the metal you plan to use, I think they may be shocked as to how much it grows.

    The brick and mortar will not expand at a rate even close to the metal.

    Chip

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  • Tscarborough
    replied
    Re: K79 Oven Build

    The fibers are a waste of time, they will burn out the first time you get it to heat.

    The wire, etc are also not needed, a simple parge coat will do just as well. The outer arch does need to be buttressed regardless.

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  • K79
    replied
    Re: K79 Oven Build

    Cat's out of the bag. I have my degree in civil engineering but my focus is on transportation not structures. I had a structural engineer from our other dept. look at my plans. Basically he told me that there isn't much difference between the soldier's and starting from the bottom using half bricks laid stretcher. The dome's weight will make the bottom brick (whichever way it is placed want to shear out). He wouldn't stamp either plan. One of the weak points is the oven entrance (obviously) since it is a break in the oven dome. Many ideas were thrown about to try and figure out what to do here. We came up with 3 options for this fix. I'm going to incorporate 2 possibly all 3 into the mix (pun intended).

    Fix 1. Much like Ken524 did on his build, I'm going to buttress both sides of my oven arch. I'll be using 1 1/2" x 1 1/2" x 1/8" angle iron formed into a triangle and held in place by 2: 1/2" studs drilled into my hearth slab. Some heat transfer here.

    Fix 2. Add fiberglass to my high heat mortar for the first 3 rings. This will essentially turn the mortar into a ring. We're dealing with about 1,500 lbs. which isn't that much. (At this amount of load there is some tensile strength to the mortar even without the fiberglass.)

    Fix 3. I'm going to wrap at the same elevation as the top of my arch some thin wire about 3 times around my oven. Starting and ending at the back of the oven. The wire will be the thickness of electric fence wire. This wire will be centered on the current ring I'll be working on and will go right over my arch forming a ring. This will work with the buttress and help hold it all together.

    When we were all done reviewing the plans we both agreed and it's proven that these ovens have and will last a long time without any of these modifications. But who knows for how long.
    Last edited by K79; 03-15-2013, 01:01 PM.

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  • david s
    replied
    Re: K79 Oven Build

    Originally posted by Tscarborough View Post
    I do not see any difference between 2 courses of vertically stacked stretchers and a solider course as as it relates to outward thrust imparted by the dome. Parge the exterior when you are done and it should be GTG.

    A sailor course is different though, it has to be reinforced or buttressed.
    The difference is that you have a full 7.5" vertical joint with a soldier or sailor course. If the bricks are laid stretcher there is only a 2" vertical join.
    Last edited by david s; 03-15-2013, 01:00 PM.

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  • Tscarborough
    replied
    Re: K79 Oven Build

    That is what the specifications are. It is no more likely to crack than home brew, which works fine too.

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  • K79
    replied
    Re: K79 Oven Build

    The Heatstop recommends joints of 1/8" or less. The rep. that sold it to my local construction outfit said to keep the joints under 3/8". He also said that anything over the 1/8" will probably crack. Seems like all the same info that I've read here. Just makes me nervous because we all know the joints will be over 1/8".

    Leave a comment:


  • Tscarborough
    replied
    Re: K79 Oven Build

    Heatstop is a very good product, I am not familiar with the other. Parging is applying a thin coat of material to the exterior of the oven.

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  • UtahBeehiver
    replied
    Re: K79 Oven Build

    I used homebrew like Mr. Chip and ditto on comments. Supervent is a rename of a Selkirt Ultra Temp double wall SS vent. I used it for my chimney. It is comparable to Duravent.

    Leave a comment:


  • mrchipster
    replied
    Re: K79 Oven Build

    The home brew 3/1/1/1 sand/hydrated lime/Portland cement/fire clay worked great for me and was much cheaper.

    Chip

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  • K79
    replied
    Re: K79 Oven Build

    What did you guys use for your High Heat Mortar? I can get my hands on Quick Bond 3000 by Allied Mineral. Also a local store has Heat Stop 50? Anyone work with these? Also has anyone here used Supervent for their chimney and accessories?

    Leave a comment:


  • K79
    replied
    Re: K79 Oven Build

    Originally posted by Tscarborough View Post
    I do not see any difference between 2 courses of vertically stacked stretchers and a solider course as as it relates to outward thrust imparted by the dome. Parge the exterior when you are done and it should be GTG.

    A sailor course is different though, it has to be reinforced or buttressed.

    This picture shows my soldier dimensions:

    Last edited by K79; 03-15-2013, 08:17 AM.

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  • Tscarborough
    replied
    Re: K79 Oven Build

    I do not see any difference between 2 courses of vertically stacked stretchers and a solider course as as it relates to outward thrust imparted by the dome. Parge the exterior when you are done and it should be GTG.

    A sailor course is different though, it has to be reinforced or buttressed.

    Leave a comment:


  • SCChris
    replied
    Re: K79 Oven Build

    K79, I understand how soldiers might be less sound, I built my oven several years ago and have soldiers and have no problems. No cracking in this area and when I built it was a question of preference. If you use soldiers you'll have a bit more room at the edge of the floor. IMO as long as you build with care your oven will be fine with soldiers.

    Chris

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  • K79
    replied
    Re: K79 Oven Build

    Originally posted by david s View Post
    Soldiers again! Do a search on using soldiers for the first course. Structurally unsound IMO.
    This is the first I've heard of that and I've posted my build for about 2 weeks now. That's upsetting.

    Leave a comment:

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