48" Mobile Oven Build

[david s]

Great work, now the fun begins with cooking in it. Did you remember to fit shocks to the trailer. Bumps and vibration are your enemy with a mobile oven.

[nuovopizzas]

It's been about a month of running my wood fired oven trailer. Everything is still working great. I am cranking out beautiful traditional neapolitan pizzas, and the oven is working perfectly. Might have dropped the dome height a little bit if I were to do it again so that I get better melting on the pizza but it is rly no big deal.

[nuovopizzas]

Hey guys,

(ALL PICTURES ATTACHED IN GOOGLE FOLDER BELOW)

I have some time to do a more formal write up of my process to get to my finished product.

Last update I left on my page, I had cast the inner dome over my fiberglass mold on my wooden table. Then I had my custom metal stand fabricated, and the big question I was facing was how was I going to transport my inner dome from my mold to my metal stand where it would sit in one piece.

Before that, I laid 4 inch CaSi board (expensive stuff off amazon) in the shape of my dome on my tabletop, with fire bricks then cut out to shape on top of that. My metal stand has a metal band that is 6 inches wider in diameter leaving me 3 inches to pour 5:1 vermiculite between it and the firebrick/CaSi board which would effectively lock my bricks in place while also allowing some expansion and contraction due to the softness of the vermiculite.

After doing that, with the help of some straps and a forklift, I cut 4 inch circular holes through my plywood, fed the straps through the outer edge and inner edge of the dome on both sides. I then used my forklift to lift it off the ground, and hammered the table down to dislodge it from the dome. (I either didn't use enough release agent, or it was just stuck after sitting for a couple months on the mold), did not release easily.

Once the inner dome was placed on firebricks, I faced the problem of getting straps out from underneath the ~400 lb dome. For this, I used a burnout technique. I changed the straps I was using to thinner ones by placing the dome down on a pallet, disconnecting the straps and connecting new thinner ones. I then used thin fire starter squares that are these thin pieces of dense material used to start fires, they have extended burn times. I placed those around edge of dome, placed dome on top, removed straps, and pretty much lit those up, and they slowly burned out and dropped dome into final position, creating a good seal between fire bricks and dome.

Steps after this were placing around 4-6 inches of insulating blanket that I picked up directly from the Forno Bravo factory in Monterey (about a 3 hour trip where I am from and well worth it to see how they do things over there). I tightened chicken wire around the fire blanket as lathe, and used a 2:2:2:2 mix sand, Portland, fireclay, vermiculite mix with AR fibers and stainless steel needles added for strength. I do not think this was the best mix and wasn't necessary because further insulation was not required for the amount of fire blanket I used. It added unnecssary weight to my oven which is not helpful for being in a trailer. In hindsight would have just done a thin layer of stucco. I also do not think this mix is very strong. I got a lot of shrinkage hairline cracking, that I think could cause some problems down the road, but I am hoping it holds up for now. It was a 1.5-2" thick layer.

I test fit my flue into my dome, made sure everything fit, used a special double wall to single wall adapter thing suggested by Giovanni to get my flue in place. and it was ready to go into the trailer. Thankfully I measured everything correctly and i used a forklift to drop the oven into the trailer through the back barn doors, I cut a hole in my roof, and place the flue in. I used a high heat flashing and sealed it with some flex seal rubber stuff.

Lastly, I had a friend of mine cut out a 5 inch granite table and arch and install that for me, gives it a professional finish.


Guys, I am astonished by the smoke pull created by this 8 inch diameter flue. Not even a little smoke ever escapes out the front.


I haven't taken it on the road yet, because I have yet to bolt it down to the frame of the trailer. Going to work on that this week. The inner dome seems very strong and I don't see any cracking anywhere, even with bringing it up to temp 3 or 4 times now. ~850*. I did about 5 or 6 small fires that I gradually grew to get the concrete used to the expanding and contracting. I kind of the just brain barfed out everything, and if you have any other specific questions let me know, because I'm sure I'm missing a lot of details that some of you might be interested in. This was a 3-4 month process and I feel like a freakin' pro now! I can pump out wood fired oven trailer all day! Now just to find out how it holds up to being on the road haha! The ultimate test.


Look at pictures here https://drive.google.com/drive/folde...usp=drive_link

[nuovopizzas]

Well fast forward 4 or 5 steps and this is what you end up with

[Giovanni Rossi]

You're welcome. Also, if you have some 1/4" or 1/2" hardware cloth laying around; that flue cap will come apart and you can wrap a piece of the hardware cloth inside to make a spark arrestor.

[nuovopizzas]

Thank you gio this was the perfect suggestion it solves a few of my problems.

[Giovanni Rossi]

Your''re probably going to need a finishing collar with adapter (8DT-FC). This transitions the bottom of your double wall to a single wall.
I think there's enough length on the bottom of that piece that could be modified to do what David suggests.

If you need more length to work with, you could also add a stainless adapter (8DBK-ADSS) or any 8" pipe of your choosing to the bottom of the finishing collar.

[nuovopizzas]

Will talk to my welder about adding some diagonals thanks for the suggestion David.

so I recently purchased my duratech 8" double walled flue and chimney cap and I need some ideas on how I can get this installed properly. Will I need to use a anchor plate? I’m beginning to think I won’t be able to do Davids method of cutting it and creating flaps because there’s insulation in it and it seems like I might damage the flue? But maybe not. I am very open to suggestions to getting this installed properly. I also can’t permanently install it until it’s in the trailer because it is going to penetrate the roof. I feel like I’m in some uncharted waters.

[david s]

I don’t know the weight that the stand will be required to support, but a 48” oven will be heavy. Without a closer inspection and from a small pic, it is more difficult to judge, but if it were mine I’d be adding some diagonals,Remember that there will be additional stress because of the shifting load in transit from accelerating, braking, cornering and road vibrations. Diagonals add little extra weight while contributing enormously to increased strength.

[UtahBeehiver]

See attached pic.

[nuovopizzas]

I just had my stand fabricated. I am now going to pretty much install my ceramic fiber board and fire bricks, and then use 10:1 perlicrete to lock it all in against the metal band. What are the different functions of 10:1 vs 5:1. I feel like I'd want to use 10:1 because I want a really high insulation value to prevent and heat from escaping out the edges of the firebricks into the highly conductive metal. Let me know.

One of my big challenges right now is finding a way to lift the very heavy one piece dome off its mold. I have the idea of sliding some straps beneath it and using a forklift to lift it up, but Im concerned about applying forces that might crack it. Only other option is to get 5-6 guys out there and lift it, but it's so heavy that Im worried someone might get hurt. Anyways, I'll continue to upload pics of my progress.

[david s]

I’ve done it many times using a double flue. I usually stuff some blanket between the two pipes both at the top and at the bottom.

[nuovopizzas]

Ok, I didn’t realise your mobile will be enclosed. You can use the roof to support the pipe so it can be fixed permanently. No need for a removable flue pipe.

That's what I figured, I'm still somewhat perplexed by the situation but I'm sure ill work out a solution lol. Do you think there is any problem with using your tab method with a double walled flue. Will the lining come out if I make tabs out of the outer layer of metal?

[david s]

Ok, I didn’t realise your mobile will be enclosed. You can use the roof to support the pipe so it can be fixed permanently. No need for a removable flue pipe.

[nuovopizzas]

You are most likely correct. The flue will penetrate a roof space, as this is going in an enclosed trailer and the flue will go out the top of the trailer. Any advice here would be greatly appreciate

I see that you can buy 8 inch inner, and 10 inch outer diameter double walled pipes, that is probably the one I will go for, but I now run into the problem that my hole is only 9 inches large, i may need to use a conversion piece or something like that, will need to put a lot of thought into it to see how this can be executed.