Nathan's 36" SoCal WFO build

[n8huntsman]

Re: Nathan's 36" SoCal WFO build

I'm getting closer to the point of creating the entry arch and thermal break so I wanna bring this up again.


I'm thinking about pouring the entry floor (pour 2 in the pic) with standard concrete first. Then before creating the thermal break, Ill build the entry arch leaving a gap for the future thermal break. Having this done before I pour the vermicrete thermal break will allow the dome arch and entry arch to act as a form for the vermicrete. The only thing Ill need to form will be the inside curved surface. I can then pack the vermicrete in from the outside and sculpt it to shape.
Am I making sense? Think it will work?

I know I've probably beat this to death but are there any more thoughts on whether I should include some sort of expansion mechanism? Graphite ribbon, or something perhaps?

Thanks for any additional insight!

[Greenman]

Re: Nathan's 36" SoCal WFO build

Looking good! Your attention to detail is showing through, bricks on bond and very tidy.

Interesting use of different size bricks to achieve that. Very nice.

[Greenman]

Re: Nathan's 36" SoCal WFO build

There has been a lot of air given to thermal breaks on the forum and I settled on light wall stainless steel at the break and filled under/over it with vermicrete. This stops the vcrete falling or failing and leaves a clean finish. It may not be the epitome of efficiency but it is tidy and stable.

[DavidApp]

Re: Nathan's 36" SoCal WFO build

Hello Nathan

Where you show the Vermicrete Thermal Break in your drawing I cut the outer arch bricks into a "L" shape and filled the gap with Wood stove door gasket. A fiberglass rope.
So far it seems to be working.
Note the low tech drawing. 3D modeling would have been a great help.

David

[n8huntsman]

Re: Nathan's 36" SoCal WFO build

Would anyone be worried about the chimney not drawing properly if part of the flue is vermicrete? I assume this will decrease the temp of the flue somewhat. I want to make sure this wont have a negative effect.
I know, I know. I'm probably overthinking it but it's a lot of work and I want the best results possible. It's just what I do. It's the engineer in me I guess.

[Gulf]

Re: Nathan's 36" SoCal WFO build

I would be afraid of it. Not the draw, but the structural aspects. And also the possibility of the vecrete slowly crumbling into the food. In my opinion it doesn't take a thick layer of insulation between the inner and the outer arches to get a great result. I believe that just a small separation between the two is all that is needed. Just my opinion .

[Greenman]

Re: Nathan's 36" SoCal WFO build

Like Gulf said. And............if you use it rather than CF rope or fibreglass rope.

Something that restrains the vcrete is necessary. It will deteriorate over time and if it is suspended then there is only one way it will go.

The use of a thin stainless barrier to contain it will not make a significant difference to the performance of the oven or the ability of it to retain heat. The thinner the metal barrier the less impact it will have on heat bleeding. I have been using mine for a couple of years and the stainless is still shiny and the vcrete is still where it belongs.

[deejayoh]

Re: Nathan's 36" SoCal WFO build

You only need a 1/4-1/2" gap for a heat break. As Greenman suggests, you can fill with CF rope. I also used a high-temp caulk. But you could just cap the break with vermicrete. The hot gas will take the easiest way out of the oven so as long as your flue is drawing it won't be a problem.

[n8huntsman]

Re: Nathan's 36" SoCal WFO build

Okay slight design mod here. I understand I only need a small thermal break but don't really want to completely redesign the stuff that remains. I've decided to form an arched U-channel to retain the upper insulating material. Similar to the entry sill that I already had planned except arched. This is made out of .012" (.3mm) stainless sheet. On the face, that leads into the chimney, I will use a 1/8" (3.2mm) stainless steel plate to retain the insulating material and prevent it from crumbling into my entry over time. Since it will now be fully contained, I'm thinking of using cal sil. or ceramic fiber blanket with a layer of vermiculite over it, then a final stucco coat for waterproofing.
Anyone see any issues with the new plan? Any preference of cal sil vs the blanket for this application?
Thanks

[n8huntsman]

Last row complete and plug cut

Almost done! Just need to mortar the plug in, pour the entry slab counter, build the entry arch, insulate the entire outside, cure it, stucco it, mount the chimney… No way the entire bar is going to be done by summer!

[Greenman]

Re: Nathan's 36" SoCal WFO build

Nice. Very tidy and for what it is worth, I like it a lot.

Your plan for the thermal break is what I would consider to be close to my ideal. I used RHS and your plan will be more efficient than that.

I am sure that you will be eating pizza well before the end of your summer and after that, it is everything in its own season.

[DavidApp]

Re: Nathan's 36" SoCal WFO build

Looks really good.
Did you turn the bricks 90 degrees in the last 2chains to make narrower pieces?

Your design mod looks like a great idea. You must have access to a sheet metal shop.

David

[n8huntsman]

Re: Nathan's 36" SoCal WFO build

Thanks for all the comments. As far as turning the bricks 90?, not exactly sure what youre seeing.
On the 5th row, I turned my brick but only out of convenience. I was previously cutting the brick in half, orienting the cut in half end to the OD of the oven, then tapering the two sides. This was 5 cuts for 2 pieces.
I realized that I could take a whole brick, cut my tapers on the side, then flip the piece that is left over and use the other side of the cut. This left the inside and outside of the oven with uncut sides. This made it 3 cuts for two pieces. Here's a pic. My original way on the left new way on the right. As I worked my way up and the pieces got smaller, I was able to cut 3 or even 4 pieces out of 1 brick with minimal cuts.
The only thing I did differently on the last two rows was tapering all 4 sides of the brick instead of just the sides. Not sure if this is what your seeing or not. On the last row, in addition to the tapers, I rounded outside of the brick to get a tighter fit.
I have access to a lot of tools, not quite a sheet metal shop, but I can make do with what I have.

[DavidApp]

Re: Nathan's 36" SoCal WFO build

Hello Nathan

I was looking at the ring next to the plug and the ring next to that. They look wider than the third ring out from the plug so I thought you may have turned the brick like the one on the left in my photo.

I think that I was cutting the brick into four at that point and getting the angles cut was getting tricky. I also rounded the outside corners.

David

[n8huntsman]

Re: Nathan's 36" SoCal WFO build

Must be an optical illusion. They are all 2.5" on the outside. The inside is slightly less on the last two due to the taper cut on the top and bottom.