Ok, figured I would get this in the right location after making a couple other post in getting started.
Here's where I'm at with my first attempt to build one of these things and a few explanations.
The base is a bit large, actually very large but it gives a place to stand and eat also. I built it to hold a 42" oven with five inches of insulation, and added a 6" overhang on the slab because I was going to brick the sides, but wife decided she had rather have stucco it and I only built a 36" oven on it. Why, a 36"? I was going to build a 42 out of fire brick, but to cut cost, I changed it to 36". Well, then I decided to build it out of castable since I had plenty of that, and my mind set was on building a 36. Half way through casting pieces, it dawned on me I could do the castable in a 42".without the extra cost, but then decided I didn't feel like going through all that work to start over casting pieces for a 42"
The base is similar to FB's design, made with 2x2x1/4" angle iron and 5/8" rebar through it in both directions every foot. The top frame was drilled so the rebar passed through it to within 1/2" of the edge and 5/8 rebar all the way around the edge. Every cross joints are all welded for extra strength. The reason for the 5/8 rebar, I had several hundred feet already on hand so I used it. To make everything fit, I made the slab 2 3/4" thick. You could probably park a M! tank on top of it.
Since I'm going to be throwing firewood underneath, I put 3/4" plywood around the sides and a divider in the middle with doors on both end. It's so big, I Didn't feel like crawling 6ft in with the spiders to get to the back of it for wood.
On top of the slab you will see a 1" cement base for the IFB and the sides are drilled every 6". This was to get the IFB up off the slab so potential leaks around the bottom of the stucco won't get to the IFB. Also a way to anchor the metal lath around the bottom when it's installed.
I will be installing 3" of high grade Fiber blanket (Maxwool HTZ 8#) around the sides and the top 1/3 of the dome will have 4".
My stucco is on order since there is none to be had locally so it's going to be a few weeks before I can install it.
The high temp mortar is used to seal the joints was air dry and not really intended to be installed as thick as I did so I'm using my fish cooker to hold it at 160 degrees until the mortar dries.
The wire you see in the side is a K Type thermocouple that's sticking approx. 1/4" through the hot face inside. There is also a 10K thermistor between the IFB and the slab just so I can see how well the IFB insulate.
The black box is my PID controller I built for my coffee bean roaster but it works great for reading my temps here also.
I cast this oven with 3" thick dome and 2 1/2" thick floor from industrial castable refractory. I think there are about 15 or 16, 55 pound bags of it in the dome and floor. The floor is in five sections in and effort to try keeping it from cracking. The dome is in four sections, also in a effort to prevent cranking. All joints in the dome are spaced at 1/4" Each section of the dome weighs approx. 130 pounds. I do a lot of bread baking so I wanted more mass to help hold the heat and hold it fairly steady. I also made provisions for a gas burner and a steam line in the slab when I poured it. The steam line will be installed for baking, the gas burner, probably not but figure it would be almost impossible to get a 4" hole through that slab after the fact with all that rebar. I only did the slab, not the IFB or oven floor, those I can drill from the bottom if/when the time comes.
Here's where I'm at with my first attempt to build one of these things and a few explanations.
The base is a bit large, actually very large but it gives a place to stand and eat also. I built it to hold a 42" oven with five inches of insulation, and added a 6" overhang on the slab because I was going to brick the sides, but wife decided she had rather have stucco it and I only built a 36" oven on it. Why, a 36"? I was going to build a 42 out of fire brick, but to cut cost, I changed it to 36". Well, then I decided to build it out of castable since I had plenty of that, and my mind set was on building a 36. Half way through casting pieces, it dawned on me I could do the castable in a 42".without the extra cost, but then decided I didn't feel like going through all that work to start over casting pieces for a 42"
The base is similar to FB's design, made with 2x2x1/4" angle iron and 5/8" rebar through it in both directions every foot. The top frame was drilled so the rebar passed through it to within 1/2" of the edge and 5/8 rebar all the way around the edge. Every cross joints are all welded for extra strength. The reason for the 5/8 rebar, I had several hundred feet already on hand so I used it. To make everything fit, I made the slab 2 3/4" thick. You could probably park a M! tank on top of it.
Since I'm going to be throwing firewood underneath, I put 3/4" plywood around the sides and a divider in the middle with doors on both end. It's so big, I Didn't feel like crawling 6ft in with the spiders to get to the back of it for wood.
On top of the slab you will see a 1" cement base for the IFB and the sides are drilled every 6". This was to get the IFB up off the slab so potential leaks around the bottom of the stucco won't get to the IFB. Also a way to anchor the metal lath around the bottom when it's installed.
I will be installing 3" of high grade Fiber blanket (Maxwool HTZ 8#) around the sides and the top 1/3 of the dome will have 4".
My stucco is on order since there is none to be had locally so it's going to be a few weeks before I can install it.
The high temp mortar is used to seal the joints was air dry and not really intended to be installed as thick as I did so I'm using my fish cooker to hold it at 160 degrees until the mortar dries.
The wire you see in the side is a K Type thermocouple that's sticking approx. 1/4" through the hot face inside. There is also a 10K thermistor between the IFB and the slab just so I can see how well the IFB insulate.
The black box is my PID controller I built for my coffee bean roaster but it works great for reading my temps here also.
I cast this oven with 3" thick dome and 2 1/2" thick floor from industrial castable refractory. I think there are about 15 or 16, 55 pound bags of it in the dome and floor. The floor is in five sections in and effort to try keeping it from cracking. The dome is in four sections, also in a effort to prevent cranking. All joints in the dome are spaced at 1/4" Each section of the dome weighs approx. 130 pounds. I do a lot of bread baking so I wanted more mass to help hold the heat and hold it fairly steady. I also made provisions for a gas burner and a steam line in the slab when I poured it. The steam line will be installed for baking, the gas burner, probably not but figure it would be almost impossible to get a 4" hole through that slab after the fact with all that rebar. I only did the slab, not the IFB or oven floor, those I can drill from the bottom if/when the time comes.
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