Nathan's 36" SoCal WFO build

[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.

[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.

[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 .

[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.

[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

[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.

[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.

[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!

[n8huntsman]

One course left

[n8huntsman]

Cleared the arch

[the_dr_masuess]

Re: Nathan's 36" SoCal WFO build

looking good! I also like the geometry.

[GianniFocaccia]

Re: Nathan's 36" SoCal WFO build

Nice craftsmanship, Nathan. I love your arch geometry!

John

[DavidApp]

Re: Nathan's 36" SoCal WFO build

The magic of 3D modeling.

Wish I had done some of that on my build. It would have helped me avoid some of the problems I had to solve on the fly balanced over my oven.

[n8huntsman]

Re: Nathan's 36" SoCal WFO build

Hello Nathan

Looking good. Very nice consistent mortar joints.
I never quiet got the angle exactly right so I got tapers between the bricks.
Is it an optical elusion or is there a slight saw tooth effect on the outside of the bricks in your last photo?
The IT tool will also maintain your circular form as well as maintaining the brick angle.
I found that on the higher courses even though I started to cut the bricks smaller I had to grind the bottom corners off the brick to reduce the gap under the brick. The corners sit in the middle of the bricks below and the span over the join in the bricks below begins to form an increasing triangle.

David

There is a little bit of a sawtooth as the bricks were tilting in on me but not as pronounced as it is in the picture. I think I can correct for that on the next course.
I noticed in my model about the corners interfering on the higher courses so I have them trimmed in my model to get tighter joints and plan on doing that on the actual bricks as well.

[DavidApp]

Re: Nathan's 36" SoCal WFO build

Hello Nathan

Looking good. Very nice consistent mortar joints.
I never quiet got the angle exactly right so I got tapers between the bricks.
Is it an optical elusion or is there a slight saw tooth effect on the outside of the bricks in your last photo?
The IT tool will also maintain your circular form as well as maintaining the brick angle.
I found that on the higher courses even though I started to cut the bricks smaller I had to grind the bottom corners off the brick to reduce the gap under the brick. The corners sit in the middle of the bricks below and the span over the join in the bricks below begins to form an increasing triangle.

David