dmun's 36" geodesic oven Pompeii Oven Construction Discuss dmun's 36" geodesic oven in the Pizza Oven Design and Installation forums; Originally Posted by need2retire Can't you just cut the standard square/rectangular fire brick into a wedge shape to build a ...

[dmun]

Originally Posted by need2retire

Can't you just cut the standard square/rectangular fire brick into a wedge shape to build a dome? This way there's no need to cut or precast a triangle piece. Seems to me putting together a dome using square/rectantular pieces is more error tollerent (deviations in measurement and motar thickness).

The problem with this approach is that every level needs to have the bricks cut to a different angle, as well as being tapered. It is the traditional way of doing it, but I devised the geodesic method because it only needed two basic shapes (which could be pre-cut) to form a dome.

The most error tolerant method is to use half or third bricks and use lots of mortar.

[need2retire]

dmun,
Thanks for your response. Quite honestly, I have no experience at all in this area. What you said about cutting bricks at different angles for each level made sense to me but
only for the sides (because the radius gets smaller as I go up in level). However, can the top/bottom (tapered ) angle be the same for all levels? Would just tapering the top/bottom sides only be enough so that the bricks will not "fall in"? This way at least the top/bottom sides of the brick can have thin motar. This way will probably have as many cuts as yours anyway

btw ... very nice work!!!

[maver]

Originally Posted by need2retire

However, can the top/bottom (tapered ) angle be the same for all levels? Would just tapering the top/bottom sides only be enough so that the bricks will not "fall in"?

If you make a hemispheric dome, then the top/bottom sides should have the same taper. Any variation from this requires differing tapers. I built a 'neapolitan' dome using the shim method (which is discussed in the plans) and I had a different shim angle for each row.

[dmun]

Originally Posted by need2retire

However, can the top/bottom (tapered ) angle be the same for all levels?

Yes, if you are building a hemispheric oven.

Would just tapering the top/bottom sides only be enough so that the bricks will not "fall in"? This way at least the top/bottom sides of the brick can have thin motar. This way will probably have as many cuts as yours anyway

This touches on an idea I had when I was planning a more traditional looking oven. Here's a picture:



The upright brick shows how it is cut in thirds, with a square face, and a six and a half degree angle needed to establish the dome. This is the "wedge" brick that establishes the radius of the dome. These are laid alternately with spacers, which on the first level are the chunks left over from making the wedges. On higher levels they need to be cut, or at least trimmed, to establish the trapezoid established by the tilting-in wedge bricks.

The idea of making these spacers to any degree of accuracy made my head explode, and made the geodesic plan seem more practical.

[RTflorida]

dmun,
your latest rendering is similar to what I originally planned. After much calulation and "test" cutting, I too scrapped the idea. Too mind blowing and labor intensive. Shame, I really wanted to attempt a near mortarless build. I settled on an angle cut of the first course to get the curve started, allowing 1/4" (and 1 - 3/8") gap between the remaining courses. I did decide to eliminate the side to side gaps, with only a minimal "glue" thickness of mortar. I'm guessing that I've been doing about 50% less cutting than my original plan, and considerably less mind trauma.

I really hope someone attempts a traditional brick dome with little or no mortar, it will be a sight to see and admire.

your geodesic dome, regardless of what you say could be done better, is truely a work of art, considerable preperation, extreme patience, and most of all - skill. I've looked this over at least a dozen times.....still scratching my head and thinking 'no way".

RT

[edschmidt]

One thought that I had about the thin mortar semi-traditional oven was to use tapered firebricks. You could run them up and cut them so that there were 4 sides and coming to a point at the top. While it would not be a true dome shape, it at least would have all sides radiating towards the center of the oven which I feel is the real advantage of the dome, as opposed to the barrelvault which has 2 flat planes radiating toward each other.

[dmun]

Tapered firebricks would be ideal, but here in the US, they are an expensive specialty refractory item. Plain low duty firebricks are about a quarter the cost.

[RTflorida]

Ed,

I think the tapered brick could be made to work, they could save you at least 50% of the headaches and labor in the pursuit of a tight fit thin mortar dome. I looked into it, the cost was way out of my league. The only two local suppliers that offered them wanted $4.50-$7.50 PER BRICK, depending on the size and degree of taper. I settled on the 77 cent standard duty firebricks.....and am cutting as much as I can stand (I've been able to get 2 courses done per day on the weekends, pretty time consuming). I honestly don't know how dmun did it, I just don't have that much patience.

RT

[edschmidt]

I actually bought 6 pallets of tapered, and large radius firebricks which are used to build a cylender for a blast furnace. Some tapers are high duty others are super high duty (90%aluminum silicate 3000deg.) for about .20 each. I might lay this up to see what it looks like with no mortar.(though its still impractical at full price ).
The guy I bought them from said they came in the building when he bought it, they ordered the materias and never built the furnace. He said that If I hadnt bought them he was going to use them for landscaping. What a waste that would have been.

[dmun]

Originally Posted by edschmidt

I actually bought 6 pallets of tapered, and large radius firebricks which are used to build a cylender for a blast furnace. Some tapers are high duty others are super high duty (90%aluminum silicate 3000deg.) for about .20 each.

Wow! You hit a home run! I felt lucky to buy plain used brick pavers for $.20, which I used for my exterior enclosure. If you measure one of the bricks I'll tell you what the angle is.