No Form Brick Oven

[dmun]

Here's the money quote from the wikipedia article cited above:

Originally Posted by wikipedia

A kiln, a kind of oven for firing pottery, may be made from firebricks with a body in the shape of a catenary arch, usually nearly as wide as it is high, with the ends closed off with a permanent wall in the back and a temporary wall in the front. The bricks (mortared with fireclay) are stacked upon a temporary form in the shape of an inverted catenary, which is removed upon completion. The form is designed with a simple length of light chain, whose shape is traced onto an end panel of the form, which is inverted for assembly. A particular advantage of this shape is that it does not tend to dismantle itself over repeated heating and cooling cycles — most other forms such as the vertical cylinder must be held together with steel bands.

What is a "low dome" oven but a low cylindrical kiln, that needs re-inforcement to keep from bulging outward. Pizza ovens are not subject to the intensity of thermal change as pottery kilns, but the same forces (and thermal cycles are still in play.

[stevest]

Camarina,

I'm considering to build my first brick oven this Spring (I live in the New York City area and it is now too cold to do concrete and brick work). I was impressed with your detailed photos. Two questions:
(1) The first row of bricks stand up straight, but from the second row up the bricks are all angled upwards (from the back of the brick) to make the curvature of the dome. But how do you know by how much to angle the bricks? Too shallow and the dome might look like a tall cone. Too steep and the dome will be rather flat.
(2) When building the cinderblock foundation, the web site says not to motar the blocks, just stack them, and fill every other hole with concrete and a rebar. But then when you pour the sub base of the oven, how do you keep the concrete from falling into the other holes that were not previously filled with concrete?

Thanks,
Steve

[dmun]

(1) What ever you decide as the form of your oven curve, you make a series of forms, out of plywood, or rigid foam, or a pile of sand, or just about anything, and use these as a guide to laying your bricks. The person who started this thread didn't use any forms, but that is the exception to the rule, and depends upon using a good refractory mortar rather than the inexpensive fireclay/sand/portland mix that a lot of people have used for the pompeii.
(2) The easiest way of not filling empty block cores is to jam empty concrete sacks into the hole.

[camarina73]

Originally Posted by stevest

Camarina,

I'm considering to build my first brick oven this Spring (I live in the New York City area and it is now too cold to do concrete and brick work). I was impressed with your detailed photos. Two questions:
(1) The first row of bricks stand up straight, but from the second row up the bricks are all angled upwards (from the back of the brick) to make the curvature of the dome. But how do you know by how much to angle the bricks? Too shallow and the dome might look like a tall cone. Too steep and the dome will be rather flat.
(2) When building the cinderblock foundation, the web site says not to motar the blocks, just stack them, and fill every other hole with concrete and a rebar. But then when you pour the sub base of the oven, how do you keep the concrete from falling into the other holes that were not previously filled with concrete?

Thanks,
Steve

I used a cardboard cutout with the curve I wanted. I made angled brick wedges on top of the first row otherwise I would have had two to two and a half inches of mortar on the outside on that row of row of bricks. In regards to the block stand, it is personal preference. I mortared the joints and filled all the cavities with concrete.

[camarina73]

Originally Posted by carioca

Inspiring job, mate! I particularly liked the arch portion. Two questions if I may: what size are your firebricks? And I notice you changed tack a bit after the first few courses to ensure the perpends don't line up - I've been thinking about this and believe I'll cut my bricks at the arch junction so as to have (half) bricks and avoid joints that line up from course to course... but I believe this shouldn't really matter in a domed oven!

Cheers,

Carioca

The bricks are 2.5"x4.5"x9.5". The only don't line up when you look straight in, but as you go around on the sides some end up lining up because the diameter decreases but the firebrick dimensions are the same. I thought I could cut bricks where they were going to line up but I was lazy to jump off and on the block stand. Its a killer on the knees.

[johnrbek]

Camarina,

Very nice work!!

What kind of tile/brick cutter did you use?

[camarina73]

Originally Posted by johnrbek

Camarina,

Very nice work!!

What kind of tile/brick cutter did you use?

I have a mk-101 tile saw
worked great except very difficult and time consuming cutting vent arch entry because of needing to cut from the 4.5 inch side.

[camarina73]

Just curious, why am I still a serf, is that something I have to change or is it automatic. Let me know anyone, I have always wanted to be a master builder.

[Frances]

Its because the number of posts you have written. Look it up under the Forum guidelines on the thread on "new membership levels"...

(And hey presto, my number of posts goes up one again! )

[jet]

camarina73,

I'd really like to see the pictures of your oven, but it appears that Yahoo photos is closed. Did you post the photos somewhere else that is accessible?