High School Geometry Method

For my 36 in. Dia (inside dimension) project in the making.

1) Floor

a) Inside the dome Area = pi X R^2 = 1017 in2 (pi = 3.1415...)

Fire Brick 4.25 X 9 = 38.5 in2 so 26 bricks

Obviously low as many cuts so

assume 36 X 36 square or 4 bricks X 9 bricks or 36 bricks.

I'll assume 35 for my project and press on.

b) Dome on Floor design 45 X 45 inch square

or 5 bricks X 10-11 (ish) 50-55 bricks

if you assume a 45 in dia circle you get 42

In the real world you probably need about 50

2) Dome -- Inside Area = 2 X pi X R^2 (half a sphere)

If R = 18 in Area = 2035 in2

Deduct 18 X 12 opening 216 in2

Net 1820 in2

If you make this out of 2.5 X 4.25 blocks (10.6 in2) you need 171 halfs or

86 whole bricks

since my dome extends 2.5 inches below the floor I need more surface area totaling about 13 more.

So call it 100

Entry arch -- 25? (eyeball guess looking at that awesome effort on the "no form" oven.

Total -- Floor 35

Dome 100

Arch 25

Total 160

Multiply that by finagle's constant and order away. Matches the 175 count within my comfort level so at least I feel confident in ordering about 200 whole bricks. With freight to HI, I'm looking at $3/each even with me picking them up at the freight yard so overkill on the count gets to be pretty good beer money in a hurry.

For my 36 in. Dia (inside dimension) project in the making.

1) Floor

a) Inside the dome Area = pi X R^2 = 1017 in2 (pi = 3.1415...)

Fire Brick 4.25 X 9 = 38.5 in2 so 26 bricks

Obviously low as many cuts so

assume 36 X 36 square or 4 bricks X 9 bricks or 36 bricks.

I'll assume 35 for my project and press on.

b) Dome on Floor design 45 X 45 inch square

or 5 bricks X 10-11 (ish) 50-55 bricks

if you assume a 45 in dia circle you get 42

In the real world you probably need about 50

2) Dome -- Inside Area = 2 X pi X R^2 (half a sphere)

If R = 18 in Area = 2035 in2

Deduct 18 X 12 opening 216 in2

Net 1820 in2

If you make this out of 2.5 X 4.25 blocks (10.6 in2) you need 171 halfs or

86 whole bricks

since my dome extends 2.5 inches below the floor I need more surface area totaling about 13 more.

So call it 100

Entry arch -- 25? (eyeball guess looking at that awesome effort on the "no form" oven.

Total -- Floor 35

Dome 100

Arch 25

Total 160

Multiply that by finagle's constant and order away. Matches the 175 count within my comfort level so at least I feel confident in ordering about 200 whole bricks. With freight to HI, I'm looking at $3/each even with me picking them up at the freight yard so overkill on the count gets to be pretty good beer money in a hurry.

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