30" castable dome

[gianlucaf]

Here are few updated pictures.
insulation done, stucco on dome done and today installed granite landing, had some scrap pieces from a neighbor and I cut out the landing.
the curve was not easy to cut, ended up with a nice rough look though.
have had about 3 fires so far. Planning on few more before waterproof stucco layer.

[gianlucaf]

Ok , thank you both .
will use dense castable about an inch or so in thickness .

[david s]

Apologies, I missed that question. I don't know the compressive strength of the product you are contemplating using, it should be available on the data sheet for it, but even a small addition of a lightweight aggregate drastically compromises the strength of any mix as the table shows. Your dense castable will have a strength of around 2000 psi, many times stronger than the strongest mix on the table. As the flue gallery is required to support the base of the flue pipe and the sides of it are subjected to bumps and abrasion, I don't believe an insulating mix is suitable in the long term.

[UtahBeehiver]

Confirm with DavidS, I think he would recommend a dense refractory for the flue gallery vs an insulating refractory for strength purposes.

[david s]

For a 28'-36" diam oven a 6" diam flue is recommended.
For the form of a cast flue gallery, I've made mine well funnelled for good flow and very shallow to make working the oven easier/ I've also made it very thin, note the butresses on the sides for strength, compensating for the thinness of the refractory. The pic should explain.If you cast around the pipe, wrap some cardboard around it that you can remove later so that the expanding pipe has somewhere to move, hence preventing cracking the casting.
https://community.fornobravo.com/for...803#post413803

[gianlucaf]

Hi all
Have some questions on flue gallery and chimney .
So, I’m done with arch , took form off after about 24 hours and still standing !!! Victory !! Although
1.Its a bit crooked on left side , slight bowout so may consider buttress column. But feels very solid , used refractory to join fire bricks . Thought ? Suggestions ?

2. Pics attach show opening for flue gallery . Dome arched entryway measures 16” wide by 9 3/4” height , its a 30” inner diameter dome .
Flue gallery opening measures 14 1/2” , wondering if good size ? Should I go smaller ?

3. planning on tapering it up to a 5” dia chimney opening, Thinking about casting flue gallery out of an insulating castable refractory “ econolite” , then get a 5” stainless chimney pipe or just use refractory bricks to do rest of chimney .
could I use regular clay bricks there instead of fire bricks ?
does anyone have plans for the form of flue gallery ? How should the tapering go ? Does it matteR ?

sorry for all the questions , first Oven and first masonry experience and kind of stuck at this point , looking for guidance .

once I have the flue gallery complete I will insulate with minimum 2” ceramic blanket then about a 1” layer of that castable insulating refractory.

then after that I plan to start curing fires .
once cured , I plan to paint on a waterproof coat of blue aqua gard from Lowe’s

then a final layer of stucco , but may go with tiles

thoughts on above layed out steps ?

john

[gianlucaf]

My very first arch not perfect but proud of it. Learned a lot .

[gianlucaf]

Progress

[gianlucaf]

Thanks David .
i have already used the castable to fill in voids.
it didn’t dry to same color as you can see in some previous pics . I sanded it down yesterday with 60 grit drinking disc and it came out pretty good , looks like it’s in there pretty good hopefully will hold up fine.

thanks for the tip on the mortar David

iM prepping the floor now . I have 1-1/2” ceramic board .
since I want to bring up the floor about another 6”,
Thinking will do few inches of vermiculite and cement , ceramic board , sand fire clay dry mixture and fire bricks .

[david s]

1. The coarse aggregate in the castable makes it unsuitable as a mortar. You could sieve it out and replace it with sand as previously described.
2. Filling the voids on the inner surface needs to be done while the casting is still moist, usually a couple of days after casting. Sieve out the coarse aggregate from a small amount of castable and mix in a little water to peanut butter consistency, forcing it into any voids. If the casting is too dry moisture will be drawn out of the mix too fast and it will not have time to adequately hydrate, resulting in failure.

[gianlucaf]

Oven’s soon to be home

[gianlucaf]

ok, few questions:
1. Should I use the same refractory cement to join these pieces together or should I use a mortar ?
I know there will be some fairly large gaps between the pieces so not sure if mortar or same refractory cement would work best.

2. should I take the time to smooth out the inside of the dome or will it really matter ? it's a bit rough but not sure how/if it will make a difference. not concerned aesthetically.

thanks

[gianlucaf]

De-molded and filled in few rough spots on the underside .
next step will be to build the floor .
so far so good .

[david s]

Yes, CAC (calcium aluminate cement)

[gianlucaf]

David,
thank you so much for taking the time to address my questions in a very detailed manner.

You mentioned CAC fully cures in 48 Hours , guessing that's short for refractory cement (btw, I used econocast 26tr from allied minerals), so thinking I should de-mold and fill in voids sometime today after 24 hours ? will it be cured enough to hold it shape and not fall apart ?

Your advice on floor is well noted , hopefully I will get to that step next weekend.
very excited to finally have this build going.
been in the works for the last 3 years

thanks again david