Planning to build a tiny oven

[Fizz]

Hi Fizz,

You are right but I just can't justify spending that much for weekend pizzas yet. Maybe if I have a lot of extra cash I'll buy either Uuni 3 or Roccbox.

Cheers,

Fvsion

Think the Uuni is about $300 , and when you start buying refractory stuff thatīs peanuts ... I got the firebricks for free, and Iīm probably in 1000-1200 dollars on my build, and itīs not even finished ...

[Rocko Bonaparte]

My mental model was a Weber Kettle because that's the one thing I did see. I'm not really convinced that Uuni's going to do much for you even without any modifications. So the idea with the kettle I had was to make an enclosed cylinder with something like:

1. Base grate
2. Floor of bricks
3. Perimeter of bricks with opening on one side
4. A grate that you manage to rest on top of the perimeter
5. The lid

The burner either goes completely under this all or is mounted with the brick floor or something. My wager was that it would be so leaky that gas wouldn't build up and pop everything off. The big fear with gas-powered pizza ovens is that the inside of the dome is sealed up, so gas can build there and cause a huge poof. If you have a hole at the highest point then you should have an escape against that. I'm currently worrying about stuff like that when planning out my outdoor kitchen. The grill and the burner are exposed from the inside, and leaked program gas can pool in the cabinets. I have to add vents at the top of the back of the cabinets so this gas can escape.

Note that if you then commit to this thing and start sealing it up with some kind insulation, then you start risking the gas pooling up.

So you probably want something large enough that it won't get completely blocked in if you create a firebrick perimeter, and preferably something where you can put bricks over the top.

Just buying some firebricks to mess around with has some merit. You might end up leaving them in your oven inside if your oven's inconsistent. They add thermal mass. It will slow the oven down but it will smooth out the cycling. So if it doesn't work out then the bricks will live a second life.

IMO those bricks are fine--and likely their thinner size are preferable--for your floor and ceiling. However, I think you'd want slightly thicker bricks for the perimeter just for some stability. I guess you can double them up.

[Fvsion]

Yeah I can't comment on using a gas burner in this case either. My own speculation is the rest of the grill may be the problem--particularly the paint or powder coating. It would seem odd that this stuff would suffer, but something that can take 500-600F just fine might start flaking its skin at a sustained 900F. As for the other bits, it gets trickier the smaller and lighter you want to make this.

I'll suggest something and you can probably tell me it sounds similar to what you already saw. It looks similar to the video. Assuming a kettle with a burner on the bottom, I'd do an experiment where I got the thinner firebricks--not the 2.5x4.5x9 bricks, but rather then ones that are 1.25" wide or whatever. Suspend them over the floor, and probably just on the existing grates. Build a perimeter by stacking cut halves of these bricks around with just an opening on one side. Cast some tiles of light perlcrete or something; maybe mix some stucco fiber in so they stay together. They will get crumbly with use, but they're so light and cheap that it doesn't really matter. Use those tiles to insulate these bricks a little bit. Lay another grate on top with a layer of thin bricks and insulating tiles. Make sure air can get into the top. Mount the lid of this kettle with the handle removed so you have one/two holes. This will let excess gas escape if it's building up and keep you from burning off your face.

It's basically a firebrick cylinder open on one side.

In this way, you can play around with the heavy materials without having to keep it in one unit that might get too big to move around, and you can tweak things to see what works before committing to something. What might just happen is this works fine for years until you eventually just build a big one.

Hi Rocko,

I think I get an idea of what you're suggesting but only slightly. Did you mean enclose it with firebricks to make a square with one side left open?

There's a supplier in my area selling firebricks that are 1x2x8 and 1x4x8 - would those work?

The reason why I would like to go through with this project is because of this video:

https://www.youtube.com/watch?v=RX4WyxoCWts

This fella modified his Uuni 2S and put a high pressure burner. If it worked for him, maybe it would work for me as well? My concern is people saying it's dangerous and it might explode or something. Is it the oven that will explode or the propane tank? Sorry for the noob questions but thanks for taking the time to answer them. I appreciate those along with your suggestions.

Cheers,

Fvsion

[RandyJ]

A big green egg can cook a pizza but the results are not any where near the same. You lose all your heat every time you open the top. There are several portable pizza ovens on the market that you may want to look in to. Just Google pizza party ovens. From what I have seen they are well rated and easily moved. They also cost a lot what a big green egg does.

Randy

[BenKeith]

Just get you a big green egg. My son has on of the large ones and luvs the thing. He claims there are a couple of mods people do to them and use them for a pizza oven. I looked at one like his, but for $1500 bucks for the one like he has (not saying you need a $1500 one) I can build my oven and do everything it can do and then some.
As for suggestions on how to build a mini pizza oven, I wouldn't know. Other than what I've read about those alternate, home brew insulations and refractories, and knowing that was not what I wanted. I don't know anything about using them. A two inch layer of #8 Max Wool will probably insulate better than a 10" of that home brew stuff.

[Rocko Bonaparte]

Yeah I can't comment on using a gas burner in this case either. My own speculation is the rest of the grill may be the problem--particularly the paint or powder coating. It would seem odd that this stuff would suffer, but something that can take 500-600F just fine might start flaking its skin at a sustained 900F. As for the other bits, it gets trickier the smaller and lighter you want to make this.

I'll suggest something and you can probably tell me it sounds similar to what you already saw. It looks similar to the video. Assuming a kettle with a burner on the bottom, I'd do an experiment where I got the thinner firebricks--not the 2.5x4.5x9 bricks, but rather then ones that are 1.25" wide or whatever. Suspend them over the floor, and probably just on the existing grates. Build a perimeter by stacking cut halves of these bricks around with just an opening on one side. Cast some tiles of light perlcrete or something; maybe mix some stucco fiber in so they stay together. They will get crumbly with use, but they're so light and cheap that it doesn't really matter. Use those tiles to insulate these bricks a little bit. Lay another grate on top with a layer of thin bricks and insulating tiles. Make sure air can get into the top. Mount the lid of this kettle with the handle removed so you have one/two holes. This will let excess gas escape if it's building up and keep you from burning off your face.

It's basically a firebrick cylinder open on one side.

In this way, you can play around with the heavy materials without having to keep it in one unit that might get too big to move around, and you can tweak things to see what works before committing to something. What might just happen is this works fine for years until you eventually just build a big one.

[BenKeith]

I probably should not be trying to answer questions because I'm no expert on this stuff and I am building my first oven now, but from what I have learned doing my research, it does not make since to build what you want when it's probably much cheaper just to buy something.
Gas burners suitable for a pizza oven are very expensive. Forge burners an not practical because they are designed to put a lot of heat in a small area. You need a burner that's going to distribute it's heat over a larger area fairly evenly. Most cheap BBQ style burners are not designed to operate inside an enclosed space that's over 600-700 degrees. Without a properly designed burner, you could easily be creating a bomb.
For a mini oven, I would think efficiency would be critical. None of these homebrew refractories are efficient and create a huge amount of bulk to be able to work. The most efficient materials like glass fiber mat, insulating fire brick and high quality castable, dense, refractory or refractory bricks are expensive also, and they are heavy. Then you have to cost of materials needed just to build molds and other stuff required to fabricate the thing.
I'm building my own because I'm building a larger, 36" oven. To buy a quality oven that size like FB makes, by the time you are done with the stand and have in completely installed is "several" thousand dollars. Since I had a couple thousand dollars worth of the needed materials on hand, and the tools and equipment, I opted to build my own, and it's still costing over a thousand, which most of that has goine into building the stand, concrete and stucco. Building the oven has cost me very little, less than $200, not counting what I've spent on materials for molds etc..

[Fvsion]

Hmmm portable do you anticipate it needs to be?

Hi Rocko,

I hope it's portable but I don't mind if it's heavy. Basically, I need something I can easily move around. Not really looking into cooking multiple pizzas at once. Been reading and watching a lot and I think I have an idea of how I want to build it. Keyword being think. lol. Not 100% sure how I'm going to go about it though.

One of the challenges I see is the mix. I see people using many different ratios and I can't decide which to follow.

Cheers,

JC

[Rocko Bonaparte]

Hmmm portable do you anticipate it needs to be?

[Fvsion]

I think you should take a look at Uuni (https://uuni.net/products/uuni-3) if small and portable are important features for your pizzamaking.

When building my own oven I realised that all things that make WFOs good are 1: heavy, or 2: expensive, or a combination of both.

Hi Fizz,

You are right but I just can't justify spending that much for weekend pizzas yet. Maybe if I have a lot of extra cash I'll buy either Uuni 3 or Roccbox.

Cheers,

Fvsion

[Fvsion]

I just clicked on the thread on a whim and saw the last post there. Just attach photos using the forum's only photo attachment stuff and you shouldn't run into bandwidth problems. We can't see the pictures.

I would look in the "Other Oven Types" forum and generally search for "refractory cast." There are a lot of recipes out there. This thread, for example, starts to go into many possibilities:

https://community.fornobravo.com/forum/pizza-oven-design-and-installation/other-oven-types/390418-refractory-casting-oven

You can ask a hundred times and get a hundred answers.

I can't speak with 100% experience on the topic since I have never casted one. I did do a pseudo-cob oven using pottery clay and pottery sand. If this oven has to be portable, then you will want to look into your perlite mix would do, but that stuff is actually insulation. Furthermore, portland cement in itself is not very strong against heating cycles. You will be relying a lot more on the flame doing the work for you, and I don't think you'll necessarily get the effect you want--especially if you're not using refractory materials on the floor to cook the bottom. They generally cast a cement/perlite mix around the outside to keep the heat in.

The mixes that go into things like sand, clay, or proprietary materials are trying to soak up heat and evenly dole it out, but they're going to be heavy. Portland cement by itself isn't the best structural binder for such heat but it's just so accessible compared to proprietary materials. Clay can take the heat and can be shaped, but it isn't good against water

Hi Rocko,

Thanks for pointing me to the right direction. The pictures are now up so you can see what I am trying to envision. My motive is basically only weekend pizza.

Cheers,

Fvsion

[Fizz]

I think you should take a look at Uuni (https://uuni.net/products/uuni-3) if small and portable are important features for your pizzamaking.

When building my own oven I realised that all things that make WFOs good are 1: heavy, or 2: expensive, or a combination of both.

[Rocko Bonaparte]

I just clicked on the thread on a whim and saw the last post there. Just attach photos using the forum's only photo attachment stuff and you shouldn't run into bandwidth problems. We can't see the pictures.

I would look in the "Other Oven Types" forum and generally search for "refractory cast." There are a lot of recipes out there. This thread, for example, starts to go into many possibilities:

https://community.fornobravo.com/forum/pizza-oven-design-and-installation/other-oven-types/390418-refractory-casting-oven

You can ask a hundred times and get a hundred answers.

I can't speak with 100% experience on the topic since I have never casted one. I did do a pseudo-cob oven using pottery clay and pottery sand. If this oven has to be portable, then you will want to look into your perlite mix would do, but that stuff is actually insulation. Furthermore, portland cement in itself is not very strong against heating cycles. You will be relying a lot more on the flame doing the work for you, and I don't think you'll necessarily get the effect you want--especially if you're not using refractory materials on the floor to cook the bottom. They generally cast a cement/perlite mix around the outside to keep the heat in.

The mixes that go into things like sand, clay, or proprietary materials are trying to soak up heat and evenly dole it out, but they're going to be heavy. Portland cement by itself isn't the best structural binder for such heat but it's just so accessible compared to proprietary materials. Clay can take the heat and can be shaped, but it isn't good against water

[Fvsion]

Hi fellas, so I wasn't able to get around to building my planned little oven due to many, many things. Anyway, I am now planning to pick it up where I left off.

I have been planning to make something similar to this:


Only I have been thinking about putting it above a typical low-pressure gas burner. I was hoping to just cut a hole at the back of the oven so that it loosely fits a burner.

Having looked around the internet, I stumbled upon the pizza hacker and found out the he just modified his 22" Weber grill and made it into an oven:


He mentioned on this video (https://www.youtube.com/watch?time_c...&v=RLC-SIGpZkE) that he made the dome using only refractory cement and perlite.

My question now is, what do you think the ratio of his cast oven is? Is it 1:1 perlite + refractory cement?

Do you have suggestions as far as the materials I can use and their ratios?

I am planning to have a sheet metal cut into a good size and then put firebricks as the cooking surface and build a dome on top of it.

Any help/suggestion would be appreciate.

Cheers!

Fvsion

[Fvsion]

http://www.instructables.com/id/How-...-Forge-Burner/

Could probably be useful...

That's very useful! Found a lot of info that I need and got me to consider the torch option. Thanks Fizz, I appreciate the help mate!