Begining dome construction

[biondoli]

I think you can still line up the rows...in the worst case you may need to remove part of the last row and re-allign everything... just more few cuts, that's what I would do. Not sure if casting cement will hold it as it is so big.
And by the way, whatever you decide sleep on it for a while...

[biondoli]

Rlf5,
forgot to ask you in my previous post...what are you using to align the bricks in terms of distance from the center and tilting? Most of us used a kind of home made compass...are you?

[rlf5]

I was using one, and then stopped (real smart, huh?). I got a bit off on the angle for the bricks on the left side, and then tried to correct for it on the next course. Seems the correction is actually the source of my woes! Anyway, unfortunately I already started casting the oven cap. I pondered on it for about a week when it was raining here. Its actually not that big of a piece...just too big to fit into my kitchen oven. Its also reinforced with steel needles so I doubt it would fall apart. The only thing I'm worried about are cracks that would form from single side conduction heating during the curing. I was just really tired of cutting bricks, and the break from doing it didn't make things better. Laying them is actually fun...cutting sucks for me...and specialized cutting sucks even more. If the cast doesn't work I'll be cutting anyway! LOL

[rlf5]

Well the pour went rather well, and came out better than expected. I let it set for about 5 days (highs in the mid 90's here) and then started doing the curing fires. I would use a few pieces of newspaper only. The paper of course burned rather quickly and the oven temperature would be back down in a few hrs, so I did about 3-4 newspaper fires over the course of two days. No problems. Then I switched it up to newspaper and small twigs (between 1/8" up to 3/4" thickness.) That fire of course burned hotter and a bit longer. I kept that fire going for about an hour or so by adding to it so that I could keep a more or less constant temperature in the oven. I found that the newspaper fires would get the dome up to about 120F and the kindling fire up to around 200. I did one last kindling fire yesterday evening for about 2 hrs, which got the dome up to 225F. That last fire actually manifested a few cracks in the thin clad of mortar I applied. I imagine they are in the joints as well, but of course I can't see it. Oddly enough, there were no cracks at all in the cast dome cap. It seems to be curing nicely so far. This morning the dome temperature was down to 95F and the cracks had settled down to just hairline fractures. I'll most likely do one or two more kindling fires before moving up to logs.

[rlf5]

The bottom form removed and first fire.

[rlf5]

Thermocouples installed and second fire. The termocouples on the right and left only go 50% through the floor bricks. The one in the center sits flush with the oven floor. There's also one that goes into the dome and is about 1/4 inch from the inside oven wall.

[rlf5]

Pictures of the crack propagation.

[Dutchoven]

Originally Posted by rlf5

Pictures of the crack propagation.

Don't worry...if it is masonry it will crack...early in the curing there is still quite a bit of moisture in the mortar and the steam has a way of creating them...they will stabilize over time...you did a very good job on your oven...continue a nice cure and soon you'll be enjoying the fruits of those labors...I have a brother in Houston, well Katy actually...if I ever go visit him maybe we can meet up
Best
Dutch

[rlf5]

Thanks! Feel free to look me up if you're ever around.

I did another fire yesterday with my first log. The floor bricks got to about 200F and the oven dome topped out at 250, if I remember correctly. The dome was back down to 100F this morning (normal day temp here). I'll try to hit 300F on the dome this afternoon...don't want to bring the temp up too much too fast.

[dmun]

Would it be better if you could build an oven with no mortar. If you could make it stand up! I know its probably not possible, but if you could.....

I actually tried dry assembling my geodesic oven on the workshop floor. If it were a full dome it might be stable enough to do that, but that big hole in the side sets up a lot of stresses in the structure. I think mortar is a must.