Portable Oven Begins

[vthokie]

Hi everyone. Four days ago I decided to build a WFO. Then I found this great resource Forno Bravo. Learned a whole lot in a couple days and today I began the challenge of building a portable oven.

Now, I'm not talking about a trailer mounted oven. My goal is to make a functional oven that 2-4 people could load into a truck or minivan. I've been researching to see if anyone else has made one and I've read a lot about people asking, but never came across a finished project.

Hopefully I'll have one.

Specifications/Goals:
Pompeii Style
24" Diameter
<500lbs
Makes deliciously sexy pizza

Progress: Days 11/09/09
Completed frame for insulation layer
rebar reinforcement
removable handles
poured 4.5 inches of vermicrete (10:1 ratio)

So far, I already think I made a mistake. The vermicrete I mixed was wayyy too liquidy. Water has been seeping through the frame and I've lost about 1/2 inch of volume. I sealed the cracks with wax and its not leaking as much, but as water leaks out the vermicrete becomes very uneven.

The galvanized tubing will be removable once the vermicrete sets. The rebar is inset into the frame so that the plywood isn't taking all the weight of the vermicrete. If anyone could give me advice or criticism, it would be greatly appreciated. Thanks for reading.

[Ken524]

Re: Portable Oven Begins

This is an ambitious project. I'm looking forward to seeing how it turns out.

What is the purpose of the galvanized pipes?

[fxpose]

Re: Portable Oven Begins

What is the purpose of the galvanized pipes?

Carrying the oven?

[dsgreco]

Re: Portable Oven Begins

From what I have read the issue with most portable ovens is the fact that they break apart from the bouncing during travel. Just something to consider. I cant help with the vermicrete as I dont plan on using that with my own oven. Good luck with your build!

[ThisOldGarageNJ]

Re: Portable Oven Begins

Hokie,
Cool Idea,,, Hope it works,, 500 lbs ?? good luck,... Is your vermicrete getting hard, or is it Just shrinking ? I would consider using FB board on top of the vermicrete.. If your goal is not baking I might also consider cutting the firebricks for the floor in half lengthwise so they will be about 1 inch high, that will cut down on the weight a lot.. you will burn more wood but you should still be able to reach pizza heat....

Good luck
Mark

[nissanneill]

Re: Portable Oven Begins

vthokie
I wouldn't have any faith in the vermicrete, even though you have a single reinforcing mesh in it to hold the oven dome. I feel that you will need something far more substantial to support the vermicrete which I feel is only an insulating layer.
Firstly I would have say a 1" high quality waterproof plywood with a 1' welded steel frame screwed to the top. This could then have access for your 'slip in carrying handles' one in each corner, then carefully cut some insulation board the same thickness to fill the areas between your steel frame. A solid sheet of insulation board over that and again screwed to the frame without interfering with your slip in handle location.
I would then buy a precast dome and secure it to the top insulation board OR get some large hearth refractory tiles and then sit your dome on those.
You then need to insulayr this and put a render coat over that.
A 24" oven will not give you a very practical nor largish cooking surface, especially if you are keep a fire going within it.

Neill

[dmun]

Re: Portable Oven Begins

Um, you know that the vermiculite concrete has no structural strength? It has a lot of strength in compression but none whatsoever in tension. I fear the first time you move that thing the ton of masonry in the center is gonna head south. Remember what the riggers say: Gravity always wins.

[ThisOldGarageNJ]

Re: Portable Oven Begins

david has a good point... maybe you ought to consider a trailer to improve portability

[vthokie]

Re: Portable Oven Begins

Thanks for the replies everyone.

Ken:
fxpose was correct, they are for carrying the oven.

dsgreco
Hopefully my dome will be structurally sound enough to withstand travel. Never laid brick so we will see...

Mark
The vermicrete is more firm than yesterday. Its no longer leaking fluids and is staying relatively flat. I'm not sure that I can make the <500lb mark as the vermicrete is already pretty heavy. I thought 10:1 ratio would make it lighter since I'm not using as much portland, but I do realize that there is a lot of water involved. As far as fire bricks, the local masonry supply store has 1.25in fire bricks which I planned on using. I calculate that I need about 32 and at almost 5lbs a piece...you get the idea.

Niell & dmun
It's good to know that vermicrete has no structural strength. I had no idea. Niell...are you saying that I should build a steel frame underneath the whole "platform?" So I guess my 3/8" plywood bottom screwed in with 16-1 5/8" deck screws probably won't hold 700lbs? I'm an idiot.

I'm really building this thing for the challenge and there is nothing like working with your hands. If nothing else, if I can learn to lay bricks into a dome, I will have gained valuable experience to build a legit oven.

[david s]

Re: Portable Oven Begins

Have a look at my little mobile oven on p.21 Finished ovens in the photo gallery. I got the weight down to 170 Kgs and the interior is 21" diam. I have cooked 70 pizzas in one night (3 x 9" at a time) with coals removed and maintaining fire on the side.I used aerated reinforced concrete for the base which sits in a steel cradle. That in turn sits on a timber trolley with 6 wheels to roll it on and off the trailer whichh I can do easily on my own.

[nissanneill]

Re: Portable Oven Begins

vthokie
I just did a sketch using Adobe Illustrator to show the construction as I would build it. It is much stronger and should hold your oven. If however it isn't and flexes, it is easy to add extra strength in the way of another plywood base. Like a house, the stronger the foundation, the longer it wilL last and the less hassles experienced.

Neill

[ThisOldGarageNJ]

Re: Portable Oven Begins

Neil has a good idea,, I also might reccomend using microlams for the sides and leaveng them there, they have a ton of strength and support..

How are you planning (besides the handles) to move it around, ie: back of a pick-up truck ?, Harbor freight has some nice big wheels and ramps that would come in handy...

Keep going as this is a cool idea
Good luck
Mark

[vthokie]

Re: Portable Oven Begins

David

That is an awesome portable oven. Do you have insulation? I see that there is a white board. Insulation? Is this sufficient? How big is your oven opening?

Niell

Thanks for the plans. Nothing like getting visuals to understand. Your plans would make it a lot lighter...Structurally, the steel should be welded together right? I'll have to see if I can find a welder. As far as insulation, is 50mm (2") enough?

I know I can get insulation board from Forno Bravo, but I'd like to get it locally. Anyone know if a big box store or what type of store would carry it?

[dmun]

Re: Portable Oven Begins

Anyone know if a big box store or what type of store would carry it?

Refractory insulation boards come from refractory specialists, or pottery suppliers for kiln building. Do a google maps search for refractory dealers near you.

[shuboyje]

Re: Portable Oven Begins

David is obviously more creative then me to cook in a 21" oven. I have a 30" low dome oven that I love, and it cooks a mean pie, but I cannot imagine, nor would I recommend an oven any smaller. I knew before I built it I wanted a larger oven in the future, but it didn't fit my current situation. 3+ months of cooking in my 30" oven has only solidified that more.