Smaug: A 36" x 16" build.

[Gromit]

Re: Smaug: A 36" x 16" build.

I'm not sure the soldier course is your enemy here. It might be, but I think your bigger problem is the stack bond.

Les, I think that the soldiers and the stack bond achieve the exact same thing: long vertical sections of nothing but mortar that invite cracks.

I have a stack bond on top of a soldier, so I should be little surprised to find it cracked.

[Les]

Re: Smaug: A 36" x 16" build.

David, I'm not sure the soldier course is your enemy here. It might be, but I think your bigger problem is the stack bond. I didn't go the soldier route so I might be full of crap. Every pic of an oven I see with a major crack has always followed the line. I would cover it with a blanket and cook something - don't sweat it.

Les

[Gromit]

Re: Smaug: A 36" x 16" build.

Dmun,

I was aware of your warnings about soldiers before I started my build, but I decided to plow ahead anyhow because I liked the look and the shape of the soldier course. Maybe it is because it reminded me of the building in this picture which is 5 miles from my house.

NOW, seeing my big honking crack in my soldier course + a lot of other hairline cracks in the soldier, I would not use soldiers again. I would possibly still try to achieve that Astrodome shape with 1/2 bricks laid on bond (is that the correct term?) since is gives a bit more volume for a given height when compared to a hemisphere.

Please feel free to point people to the pictures of my great crack in your warnings about soldiers.

[dmun]

Re: Smaug: A 36" x 16" build.

Is it just me, or are we seeing more and worse cracks with the current vogue for full brick height soldiers?

[Gromit]

Re: Smaug: A 36" x 16" build.

Here is a fuzzy pic from the inside; it has opened up a little more since this pic was taken.

The crack happened right in between when the oven turned black and when it turned back white. So, I know exactly when it happened plus or minus 18 hours.

I was more worried about it from a structural standpoint than from a worry about heat escaping--not much gets through three overlapping layers of the blanket. I was afraid I might push my hoe/rake right through the soldier wall in an errant blow. I have not decided whether to seal it up from the inside with anything. Anybody have any links to suggested products? Any good reason to bother with it?

One interesting datapoint: When I peeled back the insulation, it was a day after firing. Midway up the dome, the IR gun gave an inside reading of 350F and the same point on the outside of the dome was 340F. I would love to know the outside temperature right at the two hour point of intense firing.

[Dino_Pizza]

Re: Smaug: A 36" x 16" build.

Aw, David,
Why a crack? Do you know when it happened on your firing schedule? Without knowing the inside crack size, I would say it is about the same as mine. I don't think any heat escapes with the 3-4 layers of ceramic blanket I've got so I don't think you have anything to worry about, structurally or heat wise. You've been cooking in it so it's working fine and it's still a beautiful oven you've made, that's what's important to remember. If you decide to add any refmix to patch, it will make the gap a bit smaller but it will crack along there anyway. I filled my outside crack but I probably shouldn't have bothered. Cheers, Dino

[Rodneyf]

Re: Smaug: A 36" x 16" build.

It is a gorgeous sunny afternoon at about 22C and a slight westerly breeze.

[Lars]

Re: Smaug: A 36" x 16" build.

Hey Rodney.
What is it, like the middle of the afternoon for you now? ( 1:00am here)

Lars.

[Rodneyf]

Re: Smaug: A 36" x 16" build.

David, that is a crack for sure, what does it look like on the inside? Do you think you should fill the crack with a heat resistant filler as some others on the forum have done with success?

[Gromit]

Re: Smaug: A 36" x 16" build.

After about 10 firings, I decided to peel back the insulation and take a look at a crack that had developed during the curing fire. It looked worse from the outside than I expected, so I decided to buttress the dome with a few steel cables. One cable is anchored to the hearth slab and strung over the entry arch; it is kind of hard to see in the photos. I put the cables on the outside of the 1st blanket to protect them from the heat.

[daylight]

Re: Smaug: A 36" x 16" build.

Here is a picture of the elliptical curve for the dome - you can see how flat it would be for a large section. My more experienced helper, Les, took one look at it and said that he was concerned (code for "that will never work"). I will probably adopt your approach and go for a part-sphere. I have just drawn out the curve that will give me a dome height of just under 19" and it looks more practical - I am awaiting approval from Les!

Construction started todayso I will start a thread and document the build with photographs.

Martin.
[IMG]PhotoPlog - Dome and Floor[/IMG]

[Rodneyf]

Re: Smaug: A 36" x 16" build.

Looking good David! I am not far behind you with my oven curing happening this Friday. I hope my pizzas look as good as yours do and I am sure your tasted as good as they looked. Unlike you I don't yet have tools or even the right flour yet but I will take a trip to the local WFO pizza shop and see if he will let out some secrets as far as his flour supplier goes.

[Gromit]

Re: Smaug: A 36" x 16" build - A dome design question

Martin,

I would imagine that the curve of my dome approximates a section of a sphere. I drew it by bending a metal ruler between two points until it looked like what I wanted. Designing it in google sketchup, I used the arc tool with a 2" bend. I am a geometry dummy and could not tell you the difference between an arc and an ellipse. No worries at all about the flat part of the dome being self-supporting. When you are constructing the dome, you will see that with just the slightest angle the bricks will hold each other in place

I think that the shape with the 9" soldier course that you have in mind will be good for bread baking--it will give you more volume in the lower part of the dome. If I were doing mine again, I would use the soldier course shape, but not the soldier brick layout even though I really like the look. I would use half-bricks for the first three courses, have them rise vertically, and lay the bricks on bond (if that is the proper bricklayers term of art.)

Good luck with your build. I look forward to following it. Post pics!

[ThisOldGarageNJ]

Re: Smaug: A 36" x 16" build.

welcome to the club... your build looks great, good luck and enjoy

Mark

[daylight]

Re: Smaug: A 36" x 16" build - A dome design question

What an excellent posting and I love your design for the rotating form.

I have just purchased the bricks and mortar and am about to start construction. I have decided to go for a 36? x 18? design with a single 9? soldier course. This is because my main use for the oven will be for bread rather than pizza so the higher dome will be better. Given that I don?t intend to taper the soldier bricks, I will end up with a similar dome shape to yours.

You say that you decided on a ?non-hemispherical shape for the dome? ? is it still an arc i.e. a section of a sphere? I intended to use an elliptical cross section but having drawn an ellipse 36? wide by 9? high to fit on top of the soldier course, it looks daunting. The dome would be so flat at the top that I can?t believe that the mortar will hold the bricks in position during construction or that the structure will be self-supporting. Given that your dome construction obviously worked well, it would be great to know how you designed it.

Martin.