42" Pompeii in Eastern NC

[UtahBeehiver]

What, a tag team engineer group? I can see this oven is going to be over analyzed and engineered. So you need to step in and give your 2 cents worth. I can say this because I am a retired engineer and there are several of us on the forum from the engineering disciplines. Remember to tell them, if "mama is not happy, then no one is happy" LOL. Glad to see we talked you into a pompeli.

[Caliea]

UtahBeehiver,

You're so right about the over analysis! I have a few years experience working around them, so I think I'll be okay and
they're very quick to say it's my project, even if they look at me askance about it. So I have to make the final decisions. They're used to my wild ideas. And me dragging them into them!

Thanks for the push towards the Pompeii. It makes the most sense, but IT'S SCARY. All those cuts and compound angles! I've been reading every thread I can in order to learn from everyone else's mistakes and questions. I'll do my hand wringing here, and pretend I'm calm and collected around the engineers

[UtahBeehiver]

Since you are the sidewalk supervisor, here is a link to Deejayoh's brick angle calculator spreadsheet for those engineer types. It will help with the taper and bevel cuts on the dome as well as give you an approximate brick count. It was developed after my build but many builders have great success with the data.
https://community.fornobravo.com/for...n-the-archives

[JRPizza]

Caliea, remember that there are three ways to cut the bricks for your dome (at least I can only remember 3) - The easiest is just cutting bricks in half (will leave an inverted vee of mortar inside the oven and use the most mortar), second easiest (in my opinion) is cutting the bricks in half and beveling the sides (no vee, slightly less mortar, more complicated cuts), and lastly cutting, beveling, and tapering (no internal vee, smaller external gaps). I chose to bevel only, as it eliminates most of the mortar that would be exposed to flame in the oven (except for the arch), because several of the builders in the "what would you change" thread linked below said they would only bevel, and lastly because with the bevel only it seemed easier to get brick on brick edge contact on the inner surface of the oven. Lots of folks go the taper and bevel route, but if you are looking to minimize the cutting you might want to look into bevel only.
PS, I also used DJ's spread sheet to get my bevel angles and it got me very close. My beveling setup was not too precise though, so I used the spread sheet as a guide, I only had to bevel two bricks and place them in position to see if there were any adjustments needed. If there was I just kissed them with the saw and cut the rest of the row with the adjusted setup.
We are all looking forward to following your build.

[Caliea]

Thanks Utah for the link to the calculator. I'm going over while trying to absorb the info so I can visualize better.

JRPizza - thanks for the clarification on the methods of construction. One piece of terminology I am having trouble with: let's say the end of the brick that faces inside the oven is side A. Would I bevel the 2 sides perpendicular to A and touching the other bricks in the same course? Or all 4 sides connected to side A are beveled?

[UtahBeehiver]

See if this helps. In this pic angle aka taper. I was one who did full taper and bevel just to say I did it, but I tell builder now, like JR says, just focus on the inside joints of the build and just do a bevel near the inside dome face of the brick and let mortar fill in the backside and sides, mortar is your friend.

[JRPizza]

Here is a picture of a beveled only brick, sitting upside down on my low budget angle cutting table. There are lots of designs for more elaborate cutting jigs, but I just shimmed the 2X6 to get the angle I needed and cut my bricks. Of course I did say my setup was not too precise. At the bottom of the dome the bevels are none to slight, but get progressively larger as you approach the top of the dome.

[Caliea]

Spectacular! Thanks for the visuals - those help a ton!

I'm hoping to get the hearth slab poured this weekend, and then I'll be on to the fun stuff!

[Caliea]

We formed the shape and poured the slab today! That little sentence is so deceptive. It's hard work mixing all that concrete by hand!
I'm looking forward to getting started on the fun process of seeing an oven take shape!

[Ron-NC]

Hi, I am also building an oven (barrel) in Eastern NC - an Hour south of Norfolk. I am having great difficulty locating Hydrated lime and insulating bricks without spending a fortune for shipping. May I ask where you are sourcing your refractory items? Thanks

[Caliea]

Hi Ron,
I'm near Washington, so I've gotten my firebricks from Adams Products in Greenville. I also got some Firebrick mortar from them - they can get Heatstop 50, but it's special order and expensive. I've looked at the firebrick mortar reviews on here, and it seems acceptable, so I think I'm going to proceed with it.

Good luck with your build! Nice to know someone in the "neighborhood" that's facing the same challenges as me

[Caliea]

I need advice on the insulating board under the hearth bricks.

I was researching the FornoBravo insulating board (36"x24"x2"), and from what I can gather, I'll need 8 of the 2 " boards in order to get a 4" insulating layer. Buying from the website, that's $570, not including shipping. I've gotta admit - that hurt my feelings.

(1) Am I estimating incorrectly? I am planning on a 42" oven, adding in the 4.5" of 1/2 bricks for oven walls, it gives me approx. 51" across that I need to cover, and the front-to-back measurement would be that 51" plus another foot or so for the vent/2nd arch area. That makes it 4 panels per 2" layer, which means I need 8 panels...?

(2) Is there another option that is more cost efficient? Something I can add under a single layer of the FB Board that might not cost so much? I understand that this is a critical step, but when I figure the cost of the blankets for the top, and this board underneath, I'm at almost $1000! Makes my pocketbook wince, and not sure I can spin and polish that enough to get by my husband without some major groveling.

[UtahBeehiver]

With some effective layout you can get by with 3.5 panels per layer or 7 total. There are other brands of insulating board, IE Thermal Gold 12, Insblok 19. Local refractory distributors will carry these or something equivalent. Some national suppliers are Distribution International or Harbison Walker, most likely one of these near you. You could go with a 8 to 1 perlite or vermucilte/cement insulating base. According to a chart I have from David S. a 8 to 1 ration has a thermal conductivity (K) of 0.60+/- Thermal Gold 12 is 0.55 at 700 F..Just depends on the budget.

[Caliea]

Thanks Utah. I was having a hard time finding distributors - didn't know the proper search terms apparently I have found a Distribution International about 3 hours from me and they've been helpful.

I have ordered the insulating board for the base. Ended up going with just 2" of board, which is minimal, but within the budget right now. I plan on working up a brick jig for my saw this weekend, and getting the hearth bricks cut, and if I'm lucky and have some time, I'm hoping we'll get the first course of bricks cut and dry fit for the dome.

On that note, any suggestions on the first course? I'd like to keep it a true half-spherical dome, so am planning on using 1/2 size bricks, standing upright, instead of starting with full brick height. I haven't decided on 'solider' or 'sailor' though. My understanding is that they're standing the same vertically, but rotated 90 degrees depending on the type I lay. I'm leaning towards the sailor course, with the wider side of the brick facing the interior of the oven. Are there any pitfalls I need to be aware of?

We tore apart the slab form last night, and were pleased with the settling/packing we got around the edges, just by using a rubber mallet and lots of tapping while the concrete was wet. Not many 'bug holes'. I know it doesn't particularly matter on this slab, as it will be hidden, but we wanted some practice for when we pour concrete countertops for the project.

Hopefully I'll have some exciting pictures to post this weekend! *fingers crossed*

[Caliea]

I have a saw question. I'm in the unique position of having too many options. I have a wet tile saw (7" blade), a dry chop saw (14"), and a dry 10" compound miter chop saw.

Which will be the best for bevelling firebricks?

And as a followup - should I use a.metal masonry blade with a continuous rim or a fiberglass abrasive blade?