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Old 08-27-2009, 05:01 PM
Peasant
 
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Location: eugene oregon
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Default dome arch design

There are different kinds of dome arches. Should you try to shoot for a parabolic arch, catenary, or something else. Mine looks like a perfect half circle and that has me worried. My dome is 36 inches wide and I'm trying to get a 17 inch high dome. Nothing is mortered in yet, but it seems like it is too circular.
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Old 08-27-2009, 05:18 PM
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Default Re: dome arch design

The hemisphere is the near-perfect oven shape. It's strong, and simple and has the virtue of simplicity. There has been a rush of low-dome and eliptical section ovens here, on the theory that they are slightly better for pizza, but I vote for the half-circle.
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Old 08-28-2009, 10:49 AM
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Default Re: dome arch design

Dmun is right that the hemisphere is stronger and simpler but I think the ellipse is best for pizzas. Try for an height of 85 to 90% of the radius (in your case 18 x.9 = 16 inches)

A pizza oven cooks pizza with radiant heat. A hemisphere has one focus point for this heat. An ellipse has two focus point, or in three dimensions, a ring. The diameter of the ring (for a 36 x 16 dome) is 16 1/2 inches on the floor = the hot spot for placing the pizza.

Ellipses Calculator

A 36x17 dome has a "ring" of about 12 inches.

Last edited by Neil2; 08-28-2009 at 11:00 AM.
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Old 08-29-2009, 09:11 AM
Peasant
 
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Default Re: dome arch design

Briot,

I was in the same dilemma as you just recently. After drawing the ellipse and comparing it to the hemisphere I made my choice. The ellipse "looked better" to me. Although, I can't qualify the value of that. I didn't need a tall opening. Although, I was concerned about squeezing back inside if needed. At 10 inches it will be tight.

To make the ellipse: Mark a 36 inch straight line and measure 8 3/16th to each side from the center mark; then 16 inches high. Use a pencil and string to draw the arc. Then compare that to the hemisphere.

But, I agree, the hemisphere looks easier to build. Especially with the "indepsensible tool". I lay tile by eye. So, free forming is natural to me. To each their own. The perfectionist in me would probably want to use a tool like that though.

I'm about to start my third ring and find this process pretty fun and a reasonable challenge. I cut 22 wood shims to set the first 4 courses at a 1 inch back wedge (give or take). So far so good.
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Old 08-30-2009, 10:28 AM
Peasant
 
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Default Re: dome arch design

Does that mean my optimal cooking area is just 12 inches with my 36 x 17 dome? Ellipse and hemisphere sound about the same to me. Any pictures out there???
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Old 08-30-2009, 10:48 AM
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Default Re: dome arch design

Quote:
Does that mean my optimal cooking area is just 12 inches with my 36 x 17 dome?
Your whole dome will get hot. Some places will be hotter than others, which you can use to your advantage, choosing the cooler places when the fire is hotter, and vice versa. In pizza use, your dome is hotter toward the back, and cooler near the opening. The dome top is hotter than the floor, and you can give a pizza a final browning by lifting it up with your turning peel, a maneuver referred to as "skying". There will be more direct radiant heat close to the fire than away from it, hence the turning peel, to turn it for even browning.

As far as an optimal focus of heat, I haven't seen any evidence of it in practice.
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