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-   -   Dmun's geodesic (http://www.fornobravo.com/forum/f28/dmuns-geodesic-3656.html)

Xabia Jim 03-29-2008 09:05 AM

Dmun's geodesic
 
Dave, now that you've used your oven a while, how has the dome held up.

There was concern expressed about all the pieces and potential for cracking. Did you experience much? Any difference between the panels you made and the joints when putting the dome pieces together?

It really was a great project!

Jim

dmun 03-29-2008 11:02 AM

Re: Dmun's geodesic
 
Thanks for asking.

Yes, the oven cracked. The largest and theoretically most worrysome crack was in the front refractory arch, that spans my wide tapered doorway.

http://www.fornobravo.com/forum/phot...cracks_001.jpg

Similarly, the inner oven arch cracked at the top. It looks worse than it is, because a piece of mortar fell out here.

http://www.fornobravo.com/forum/phot...cracks_002.jpg

The inside of the dome has quite a few hairline cracks. In one place, where the sections didn't line up, i smoothed heat-stop mortar on top of the bricks to level it out, and a bit of this surface mortar has fallen out. There doesn't seem to be any difference between the joints between polygons, and those within them.

http://www.fornobravo.com/forum/phot...cracks_003.jpg

Since the entry is so much cooler than the dome, and the joint between the two is a running seam, you would expect a crack there, and sure enough there is one.

http://www.fornobravo.com/forum/phot...cracks_004.jpg

This isn't a curing problem, my oven sat for months between when I finished the dome and built the chimney. I didn't start curing fires until the chimney was finished. For those new here, I have an almost two story masonry chimney stacked on top of my dome. The outer masonry shell is supported by a reinforced concrete bridge over the oven, but the weight of, what, 7 or 8 pieces of 8" flue tile are stacked up on top of the dome.

Happily, I had spent a year here before my first fire, reading posts with titles like "Enough with the cracks already" so I wasn't too concerned. I'm still not. None of the cracks have gotten any worse, and each element of my dome is tapered on every side, so there is no possibility short of a Chile caliber earthquake that any part is going to fall in.

In retrospect, I'm not sure there is any benefit to having a dome that thin. The geodesic pattern is neat to look at, but so is the traditional brick pattern, and as has been said, you don't see it that much anyway. My heat up times are similar to those with half brick domes. My cool down times are faster too, not that I'm going to undertake multiple bread bakes. It stays hot enough to cook a turkey, and that was my heat holding goal.

I suspect that the cracking is caused my not having a dome that conforms to the ideal structural form of the catenary arch, and a full cantenary dome is of course way too high for best oven practice. I think the ideal oven is one where the walls of the dome are thick enough to internally enclose the imaganary cantenary curve, but low enough so that the top of your pizza cooks.

Les 03-29-2008 11:13 AM

Re: Dmun's geodesic
 
It just occurred to me that the FBI is probably going crazy with this web site - way too much discussion about crack. :)

David - if you are cooking with it - job well done; and it still stands today as one of the most impressive builds.

Les...


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