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  #11  
Old 07-22-2005, 06:07 PM
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i think the herringbone pattern makes the most sense, as it it designed to have as few running seams as possible. i did my floor in something of a herringbone pattern, but mostly was trying to cut down on seams perpendicular to the "in and out" dierection of the oven.
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  #12  
Old 08-09-2005, 01:44 PM
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Default Many and varied unrelated oven questions

I hope that I am not abusing the posting protocol by posting so many unrelated questions but all of them have to do with oven construction. If James reads this, please let me know if you would have preferred my starting a new "thread". If you reply to any of my questions, would you kindly number them as I have? Thanks.

The clearest construction photos I've seen are those of Jim Hatch ( Col. Corn) on his Yahoo Site, photos.yahoo.com/colonelcorn76

1- I am using those for planning, such as counting the number of concrete blocks, etc. If anyone knows of additional clear photos I would be glad to supplement my resources __________

2- I will pour 3,000 psi transit delivered concrete into a 10'x10' form of 2x6. I have laid down 3/8th in re- bar, 2 sticks about 6" apart only on the perimeter where I estimate the block wall will later rest. I have been told that the placement of the re-bar is not critical. Your comments? _____

3- The block wall will be placed, when facing the first slab, at the extreme rear and as far left as possible. This placement is to allow us some extra slab on the right, and a front apron of perhaps 40"? Is there any problem anyone sees in situating the walls off center? ______

4- I am trying to plan way into the future as sometimes the later steps hinge on the initial ones in ways I wouldn't otherwise foresee. I notice an angle iron which supports the arch opening bricks. Is there any reason I should not make relieving V cuts and bend that angle iron to conform to an arc of the 42" circular floor? ____

5a- Different builders have modified the curve of their domes; parabolic, and hemispheric. I am drawn to the hemisphere. If I place the first course of firebrick on their shortest edge, is that first course set up so that the maximum width is utilized for greater thermal thickness? ____________

5b- Do I place the first course of soldier bricks on the herringbone circular base firebricks, or next to the perimeter of that circle? ___


6-If I proceed as above, and want to construct a hemisphere, presumably only the outside "cladding" would approximate that profile. If I use the styrofoam temporary bracing for the firebrick and cut those styrofoam supports in a true hemispshere, and place them *on* the first "soldier" course, will I end up with a dome too high because the first row (course?) becomes a part of that so called hemisphere? _____

7- I would like to post images on the forum. Mary's camera seems to provide too high a resolution for the forum to accept. Is there a way to reduce the file size within the forum tools? ____________

That's about all I dare to ask out of context but I know I'll have many more questions as the building progresses.

Ciao,


Marcel
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  #13  
Old 08-09-2005, 03:47 PM
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Marcel, sounds like you're covering all the bases. A few responses:

5a. is that first course set up so that the maximum width is utilized for greater thermal thickness? all courses are half bricks. the oven walls should have a uniform thickness from top to bottom.

5b. Do I place the first course of soldier bricks on the herringbone circular base firebricks, or next to the perimeter of that circle? on top of. the ragged edges of the base will extend beyond the circle circumscribed by the outer edge of the first course.

6. will I end up with a dome too high because the first row (course?) becomes a part of that so called hemisphere? not necessarily, if you angle the remaining courses correctly. my dome ended up a few inches too high (which is preferrable for roasting and seems to work fine for pizza as well).

7.Is there a way to reduce the file size within the forum tools? i defer to james but i don't think so. a quick and easy way to copy a folder full of photos into a new folder with much smaller pictures is by using the export feature of the free picasa software available at http://picasa.google.com/index.html
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  #14  
Old 08-09-2005, 04:50 PM
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marcel,
i might be able to help answer a few of your questions as well...

1. i have taken some pretty detailed photos of my construction. i have limited which ones to post, so the thread is not enormous, though my pictures are not actually in the forno bravo database, but rather hosted by another site. if you would like to see specific sections, just let me know. i'll probably organize them at some point and post a link to all of them.

2. I would place rebar wherever there will be a significant load, but if you are not digging a deeper footing where the block stand will actually sit, i would place it throughout the whole slab. actually, rebar is cheap---i would just over-reinforce it if anything.

3. I'm not sure if i completely understand your question, but as long as there is significant reinforcement in the hearth slab and your hearth is sitting firmly on the block stand, there shouldn't be a problem. just make sure the stand is evenly taking the load.

4. cutting either face of angle iron will comromise it's strength significantly, unless you weld each cut back together after bending it. even then, it will likely not be as strong, unless you are a proficient welder.

5b. most people place their walls on top of the floor, because the floor is layed out roughly, with the jagged edges extending beyond the walls. however, i cut my floor round, and placed the walls around the floor instead, believing that this would make it harder for heat to escape beneath the wall. i can't speak for the other method, but this way worked well for me. the very bottom of my wall on the outside (the ones butting against the sides of the floor bricks) is about 50 deg. cooler than 3 or 4 inches higher, where they actually face the interior of the oven on the inside. also, this way heat is not escaping through the protruding floor bricks.
but this does require the added labor of cutting the floor bricks round.

6. when you lay out your bricks on the ground to decide the shape of your dome, just include this first taller layer in the cross section, and then proceed to make it however high you want it.

7. i download my photos onto photobucket.com (it's free), then copy and paste their html link onto my posting. this doesn't take up any space on forno bravo, but rather loads the photo from the host whenever you view it on the page. you could do the same with yahoo, or anywhere else that does photo hosting for free. the disadvantage would be fornobravo not having them in their database if the host ever went down.

good luck with your oven!
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  #15  
Old 08-11-2005, 05:40 PM
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Quote:
Originally Posted by Marcel

1- I am using those for planning, such as counting the number of concrete blocks, etc. If anyone knows of additional clear photos I would be glad to supplement my resources __________

===> Check the files section of the Yahoo group. I posted a block diagram that has a page for each layer and a block count & size by layer.

2- I will pour 3,000 psi transit delivered concrete into a 10'x10' form of 2x6. I have laid down 3/8th in re- bar, 2 sticks about 6" apart only on the perimeter where I estimate the block wall will later rest. I have been told that the placement of the re-bar is not critical. Your comments? _____

===> Wow. Transit mix in that small a batch is really expensive here. I went the bags of Quikrete along with a mixer rented for a couple of hours. As for the rebar, place the first row about 3" in from the edge and then the next parallel ones about 2" further inside. You can get rebar mounts which are little wire saddles with depressions to lay the rebar into that you can lay them on. You'll have 8 pieces of rebar -- 2 on each side. Over that, I'd recommend a layer of mesh but since it comes in big rolls, see if you can get some wire fencing with the 2x3 inch grid pattern (or something close). Lay that on top of the rebar & tie it all together with twist ties or those plastic zip ties.

3- The block wall will be placed, when facing the first slab, at the extreme rear and as far left as possible. This placement is to allow us some extra slab on the right, and a front apron of perhaps 40"? Is there any problem anyone sees in situating the walls off center? ______

===> Not me. Just slope it a bit to keep the water from rain from flowing into your wood storage (if you plan on using the underhearth space for storage).

4- I am trying to plan way into the future as sometimes the later steps hinge on the initial ones in ways I wouldn't otherwise foresee. I notice an angle iron which supports the arch opening bricks. Is there any reason I should not make relieving V cuts and bend that angle iron to conform to an arc of the 42" circular floor? ____

===> You can. Not sure it's worth the effort. Also, the straight piece makes for a nice flat backing for the chimney vent and a flat face for the door you'll want to build for cooking bread or slow-cooked roasts/turkey/etc. The cuts weaken the steel but it's not structural in the sense of long term support of the bricks. Once the mortar sets up, those bricks that rest on it will be fine even if it disintegrated.

5a- Different builders have modified the curve of their domes; parabolic, and hemispheric. I am drawn to the hemisphere. If I place the first course of firebrick on their shortest edge, is that first course set up so that the maximum width is utilized for greater thermal thickness? ____________

===> The Pompeii is a section of a parabolic spheroid. That's typical of Tuscan ovens which are suited for both bread & pizza. A true hemisphere is not as efficient in drawing the air & washing the full surface of the dome with flame & smoke for most efficient transfer of heat (conduction, convection & radiation). A hemisphere is also not as strong in holding the arch as the force vector pushes outward more than downward. The parabolic design redirects the gravitational forces downward as the ancient cathedral builders found with flying buttresses.

5b- Do I place the first course of soldier bricks on the herringbone circular base firebricks, or next to the perimeter of that circle? ___


===> On top of. Butter your mortar all the way down and you'll have an airtight and thermally efficient bond. Paul did his by cutting the inner hearth bricks in round slices and placed the soldier bricks outside the hearth bricks. That's a lot more work but doable. I don't believe there is a significant difference in performance of the oven.
My answers are instream with ===> in front.
Jim
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  #16  
Old 08-11-2005, 06:37 PM
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BTW jim, i don't believe there would is a significant difference either, i just wanted to try it and it turned out to be relatively easy.
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  #17  
Old 08-12-2005, 07:55 AM
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Default Special thanks to James, Jim, Paul, and Robert

I had written a long letter of appreciation to you and then checked the spelling of grateful, only to lose the letter. Oh well, maybe the universe is telling me to cut it short.

Your assistance has given this senior citizen the confidence of a youngster!

Ciao,

Marcel
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