Fio's 35" Oven

[Fio]

I've posted in other threads but I don't want to hijack, so I'm starting my own thread.

Here are some pictures of my progress. I poured the slab in March, 2006 and have been building since then. I enlisted the help of my buddy to do this - a lifesaver - because I had no idea mixing concrete was so freaking hard. I should have plunked down an extra $300 for a cheap mixer.

I poured the base planning to build a tiny 24" X 30" Alan Scott oven - my first mistake.

My second mistake was that I built up the base block by block, mortaring each joint. A wonderful exercise in masonry; a complete waste of time. I wish I had found this forum before I did that.

If I had to do it over, I would have dry-laid the blocks and filled the voids with concrete. I could do in one day what took me three weekends.

[Fio]

Instead of pouring a hearth slab, I used slag lintels

Slag lintels are concrete beams, reinforced with rebar. The advantage is that you can span the gap without mixing a lot of concrete. The disadvantage is that they weigh a TON. These 48" lintels weigh 120 pounds each. I needed to procure the assistance of my buddy Dave, to whom I now owe much pizza.

Another mistake I made was that I built a completely sealed base. This required the addition of a foundation vent.

[Fio]

To get a smooth hearth slab, I added a 2" slab of concrete

I did not need to reinforce this thin slab, because the slag lintels are reinforced.
I built a form, propped it up, and filled it with concrete. Now I have a nice smooth surface for the hearth.

[Fio]

Two inches of high density fiberfrax board for hearth insulation

Instead of mixing cement and vermiculite, I opted for thermal insulation board. This is not cheap, but it's effective and very neat.

The firebrick floor goes on top. By now I had decided to abandon the Alan Scott plan and build an igloo. I left myself so little room that I'm going to have to use every square inch I have.

Once the floor is mortared in place, I used a pizza peel to feel around for uneven sticking points. I marked these with chalk, and ground them down with an angle grinder.

[Fio]

The dome form is made from 1" thick styrofoam

I was inspired by Kiwi Pete and Drake on this one. The dome cannot be a hemisphere, because the first two rings are vertical.

I cut out two 35" discs from the styroboard (I had to glue two 24" panels together using polyurethane "Gorilla" glue). I built three 5" spacers using scraps and drywall screws. The spacers are sandwiched between the discs. The resulting platform is 7" high. The vanes are added (glued with more urethane glue) to create a resulting dome height of 16." I think there are 24 vanes total.

[Fio]

At last - NOW I can start building the dome!

I laid out the first two courses to test the fit, then started mortaring.

As you can see, I could still use a few more vanes. The goal is to have the gaps between the vanes smaller than the width of a brick.

Styrofoam is easy to work with: you cut halfway with a utility knife, then break it to complete the cut. But it doesn't break cleanly.

As I build the dome, I'll no doubt have to trim and shave the form to allow a good fit for the bricks.

[DrakeRemoray]

Looking great! Thanks for the pictures. 16" dome huh? I hope I did not make my dome too high (20").

Drake

[Marcel]

Doesn't look as big as an Egyptian pyramid.

(M) Thanks for all the pictures which were very helpful in visualizing the size of a 35" oven. I counted the concrete blocks in your Hearth Stand and it appears you have 48" on at least 2 of the sides. I can't tell if your stand is square or rectangular.

(M) Do you have a wood storage area? From one of your posts I inferred, "no".

(M) Fio, with such a small oven, and standard size refractory bricks, you should expect fairly substantial mortar joints on the dome. They will not be visible.

(M) I think I understood the cat metaphor; you're telling us that "There's more than one way to skin a cat!" but I missed the meaning for the empty beer bottle. What good is that, anyway? Did you use it to roll out your mortar? What did you use the beer for?

(M) Those bull-nose red bricks are not available near me in Oregon. They look great. Where do you live? ____

(M) You're welcome for the "Thank You" you sent to me in a private message. So, .... were you using pre-packaged mortar or cement? ___

(M) You know, if you had a firebrick for every time you've modified your oven plans, you could build an oven the size of an Egyptian pyramid.

Ciao,

Marcel

[arevalo53anos]

Fio:



I hope this question did not be posted to late.

It is not the hearth too big?

When baking the mass is important to retain heat, and so is when heating, consuming more wood or time to reach the target temperature.

You are going to bake only in the inner of the dome oven.

May be you would like to consider to use an island hearth.

By the way, nice work!

Luis

[Fio]

Replies to your comments.

(M) Thanks for all the pictures which were very helpful in visualizing the size of a 35" oven. I counted the concrete blocks in your Hearth Stand and it appears you have 48" on at least 2 of the sides. I can't tell if your stand is square or rectangular.

(F) Yes, the base is tiny; 49" X 56". It's too small and I'm stuck with it.
In retrospect, I wish I had allowed for wood storage. But the lack of one will add only a minor inconvenience.

(M) Do you have a wood storage area? From one of your posts I inferred, "no".

(M) Fio, with such a small oven, and standard size refractory bricks, you should expect fairly substantial mortar joints on the dome. They will not be visible.

(F) I AM concerned about the large mortar joints. Already I have 1/8" gaps in between the first and second ring (too much mortar?). I hope these will be OK since they're near the bottom of the dome. I have considered the large gap coming up, as the dome turns from vertical to sloping inward. I will use wedges of firebrick to fill that gap and minimize on mortar.


(M) I think I understood the cat metaphor; you're telling us that "There's more than one way to skin a cat!" but I missed the meaning for the empty beer bottle. What good is that, anyway? Did you use it to roll out your mortar? What did you use the beer for?

(F) The cat was my helper. As for the beer, I have still not found a good use for it, so I use it to quench my thirst.

(M) Those bull-nose red bricks are not available near me in Oregon. They look great. Where do you live? ____

(F) I live in Arlington, VA, near Washington, DC. A brickyard in Alexandria has all sorts of bricks. I'm sure you can find them at a good brickyard.

(M) You're welcome for the "Thank You" you sent to me in a private message. So, .... were you using pre-packaged mortar or cement? ___

(F) For the dome building? I was using Portland Cement/sand/fireclay mixture according to the FB recipe. I used Sakrete Mortar Mix for the base and all the non-heated surfaces.

[Fio]

Fio:



I hope this question did not be posted to late.

It is not the hearth too big?

When baking the mass is important to retain heat, and so is when heating, consuming more wood or time to reach the target temperature.

You are going to bake only in the inner of the dome oven.

May be you would like to consider to use an island hearth.

By the way, nice work!

Luis

Luis,

Thanks for the question. with the exception of one or perhaps two bricks, every brick on that hearth is either inside the dome, supports the dome, or is part of the landing. I will remove whatever hearth bricks are completely outside the dome. Thanks for the advice.

Plus, I think that the insulation on the bottom (and there will be insulation on the exposed sides) of the hearth bricks will effectively "trap" any heat transfer. So the actual extra mass that will suck heat away outside the dome is fairly small. Does my explanation make sense?

Thanks again.

- Fio

[FioBro]

Very nice job, little brother!!

Being Fio's older brother, and planning on being there for one of his first pies to come out of his nifty, hand-crafted oven, I figured I better get on-board and get involved...

Keep us informed on your progress, and lemme know when I should buy the plane tix...

Brother Vito in Ra-Cha-Cha

[james]

Lol

As a younger brother myself, I have to welcome Fio's older brother to our group. Eccellente.

I think this is the first time someone has joined to witness a sibling's progress -- with the prospect of enjoying some great pizza. Ma lei deve montare suo proprio forno. Subito.

Welcome aboard Vito. Good food is in store, but you have to send photos.
James

[Fio]

To Handle The Aggressive Curve, I used Wedges

My dome design incorporates a sharp change from vertical to sloped. To handle the change, I used a course of wedges.

[Fio]

I liked Kiwi Pete's Idea of Casting an Exhaust Manifold

Instead of casting a lintel and a manifold, I used angle iron lintels and plopped my exhaust manifold on top. I'll put a chimney flue on top.

After careful planning using a styrofoam mockup, I built a mold out of leftover styro board from the dome form. Having no access (can you believe it - in Washington, DC?) to alumina cement, I made a "concrete" out of HeatStop mortar and crushed firebrick. What a PIA it is to crush firebrick.

It turned out nice, though. The mortar sets FAST. I threw in a few pieces of 3/8" threaded rod as "rebar." Hope it holds together.