Mobile Forno Finally started!!

[FIREANDFLAMES]

Re: Mobile Forno Finally started!!

Any updates on the mobile oven? Id like to see new pics!

[ikhan42]

Re: Mobile Forno Finally started!!

I've finally got an axle for the trailer and I have a buddy that's going to go over my welds one more time.....I want to be sure it's strong enough after i put all this work into it....So I should have some more progress reports with photos in the next 2 weeks or so.

Is there no way that you can rig a dual axle on the trailer may be a smoother ride and a safer ride.

Imran

[aferaci]

Re: Mobile Forno Finally started!!

I've finally got an axle for the trailer and I have a buddy that's going to go over my welds one more time.....I want to be sure it's strong enough after i put all this work into it....So I should have some more progress reports with photos in the next 2 weeks or so.

[bdasko]

Re: Mobile Forno Finally started!!

Hey any updates on this project?

[fortran]

Re: Mobile Forno Finally started!!

I finally tracked down how to find information this insulation idea. Call it multilayer insulation. Anyway, a paper from NASA in 2001 had some data. They are insulating a space that is 3 inches deep, so similar thickness to under the oven. They ended up using 16 foils (reflective layers) in the stack. It is possible to have too many foils, but worse to have too few. NASA was using an alumina based wool between foils, I seen a different report using glass fabric between foils. Probably anything works. You want the foils shiny. Since the oven weighs quite a bit, you might want to use spacers of some kind to support weight. They will thermally bridge, so you want to stagger them as much as possible. Stainless steel might be one idea for a spacer material, but anything mechanically competent should work. I would think something like mutton bars in a window in terms of putting them between foils. The foils don't have to be as thin as household aluminum foil.

[fortran]

Re: Mobile Forno Finally started!!

Someone had asked about fiber reinforcement of concrete. There are 2 classes of fiber reinforcement: polymer fibers and steel fibers. Polymers are significantly less dense than the concrete, and steel is significantly more dense. Both can suffer from segregation. I think concrete gets more complicated, in that you need viscosity control and wetting agents to try and manage the segregation. Vibration after pouring also needs to be controlled. Polymer fibers are likely to get into a melting/burning situation close to the hearth floor.

If you want to surface bond the concrete blocks for the stand, it looks like +/- 45 degree cloth embedded in epoxy is what to do for maximum shear strength. Some people (civil engineers re-inforcing bridges) are using glass, some are using carbon fiber. Glass is probably okay for mobile wood ovens.

In terms of heat transfer (insulation), I wonder how a stack of thin sheets would do? If a person had access to cheap aluminum foil, a stack of aluminum foil that was 4 inches thick (compressed) would have a lot of layers to it, and heat would not transfer across the layers very easily. Heat would equalize within the layers very easily, and 900 F isn't too hot for aluminum. Being metal, it wouldn't break very easily. I haven't tracked down any experiments in this regard, just "idle thinking" at this point. To build an oven doing this, and find it wasn't good enough would be annoying.

If you want a practical example of the stack of aluminum sheets, you can make up a bunch of aluminum sheets as a heat shield for soldering of plumbing. Quite often a layer or two melts, as the flame is too hot for aluminum, but it doesn't take many sheets to keep from scorching wood or paper (drywall facing) on the cold side.

[Xabia Jim]

Re: Mobile Forno Finally started!!

I'm not sure if I'm going to use the end with the hole yet !!!

Are you going to use these for your hearth? How will the thermal mass be?

... why not cut through the hole and use 1/2 blocks with the cutside/hole down? That would leave you with the original surface up from the... 8x6x24?. It sounds light enough, would the 6" hearth be overkill?

Jim

keep us posted on this project, thanks

[fortran]

Re: Mobile Forno Finally started!!

I have done a little research into this, more in terms of a "luggable" oven than something mobile, but testing would be the proof.

Working from the Pompeii design, I would think using 1 fewer courses of cement block would be something to consider, maybe 2 courses less, since the "ground level" is now above axles. You could however stay with the same number courses, since the room underneath is good for wood storage I gather.

Mortar is not very strong, typically less than 10% of the strength of the concrete blocks. Probably the thing to do is to dry stack the concrete and then surface bond the blocks. Normal surface bonding for housing, uses a fibre reinforced concrete mortar, but with bridge infrastructure of concern around the world, civil engineering has started looking at stronger systems. One paper used carbon fibre reinforcements in epoxy for the surface bonding. You do need to use a primer on the concrete, and possibly special epoxy (concrete has a high pH). You would want to surface bond both sides of the block, and you wouldn't need to fill the cores with concrete and rebar. Which would save you a fair amount of weight. I would plan for a steel bolt to come up from the steel frame of the trailer through the hollow cores, to a steel plate on the top of the stand, to hold the stand rigidly. That should allow the stand to be rigid enough that the oven shouldn't see any flexing.

Any wood in the structure, such as at the top of the stand to place the stove onto, might be better if you impregnated it with a penetrating epoxy. It won't see sunlight (UV), so you don't need to protect the epoxy. This would probably remove rot from consideration. A mobile oven would probably see some water getting onto that wood. Exposed structural wood that was treated with epoxy should be painted with a good paint. If you paint it before the epoxy has completed curing, the epoxy will hold the paint very well (oil based paints).

I would think it would be a good idea to "shave" the bricks making up the domed oven. That would probably help to minimize how much mortar you use, and at the same time might even increase how much area mortar is on. My feeling is that if the mortar is thick anywhere, any flexing of the oven is going to make that mortar crumble.

It would be interesting to see how this project goes.

[aferaci]

Re: Mobile Forno Finally started!!

Well, I went and got the AAC block today. Below are some pictures of them. I got 12 block in all that measure 8"x12"x24". I'm not sure if I'm going to use the end with the hole yet and just fill the hole with perlcrete or if I'm just going to cut that piece off. I am going to split the block down the middle of the 8" side though, making 2 4"x12"x(16" or 24") pieces per block. The guy at the jobsite said these block go for about $12-$14 a piece and I got all 12 of them for a $11.99 cae of Budweiser. And he told me that if I needed more that I could come back and get them. What a deal!!!

[gjbingham]

Re: Mobile Forno Finally started!!

Sounds like a good and solid solution for a mobile oven. Great find!

[RCLake]

Re: Mobile Forno Finally started!!

For a case of Bud , who got the better of this deal. No just joking, I looked into this as my floor insulation and Dmun posted a thread that had discussed it. Still think it may be a cheap way, if it would hold the weight.

Show us how you are going to do the door. Could be basically a plug attached to a good looking door.

At least have the beer cold when you deliver it and you can probably have a couple.

[Ken524]

Re: Mobile Forno Finally started!!

Budweiser seals yet another deal!

[aferaci]

Re: Mobile Forno Finally started!!

Well, this problem seemed to solve itself today. I was riding by a jobsite today and noticed that they had some left over AAC (autoclaved concrete or Aerocrete) concrete leftover. I talked to the jobsite super and after I told him what I needed it for he agreed to let me have as much as I needed for a case of Budweiser. This stuff is nice and thick and strong but it's so light. A 8"x8"x24" piece only weighed about 5 pounds. So I will go get this stuff tomorrow and post pictures of it.

[Ken524]

Re: Mobile Forno Finally started!!

So all of the other people on this forum who made their ovens with vermiculite or perlite slabs were skimping too?

They weren't skimping. The vermiculite/cement base works very well. If you do a search for messages about vermiculite on the forums, you'll see that it's stable and can take the compression forces of an oven. But it is very susceptible to chipping and shear forces. That's why we are concerned about a mobile installation. We don't want the "shake, rattle and roll" of a trailer to damage your pride and joy.

CanuckJim suggested Matrilite 18, a castable product. That might be a good cost vs. stability compromise.

[aferaci]

Re: Mobile Forno Finally started!!

So all of the other people on this forum who made their ovens with vermiculite or perlite slabs were skimping too? Thanks for answering my original question-you were so helpful