I'm getting closer to my Dome!

[brickie in oz]

Re: I'm getting closer to my Dome!

Just read through your post again, putting the floor inside the dome is not something I would do.
Heating the oven, the floor has to get hot quicker and expand first, it is also a bigger mass than the dome so would expand more than the dome.

I wonder how many other cracked domes are due to this?

[Aegis]

Re: I'm getting closer to my Dome!

Just read through your post again, putting the floor inside the dome is not something I would do.
Heating the oven, the floor has to get hot quicker and expand first, it is also a bigger mass than the dome so would expand more than the dome.

I wonder how many other cracked domes are due to this?

Al, Normally there is an 1/8" gap/separation between the floor and the walls of the dome. I used some firebrick shims to keep my plywood holding the indispensable tool in the center. I am sure some broke off and I no longer had that gap. Just a really careless error on my part, but I tend to now agree with putting the wall on top of the hearth bricks so stupid people like me can't mess it up! lol How many hearth bricks along the wall will ever be replaced? That is the reason for the hearth as an Island. So you can replace damaged hearth bricks. That now seems like a weak reason.
I'll take some pics after Irene the terrible passes through New England. I may not have power for a few days so pics will wait.
Thanks
John

[woodfried]

Re: I'm getting closer to my Dome!

Hi John
Hope all is well over there with the cyclone as we call em ,
Interesting re floor inside dome , I just couldnt be stuffed with the extra cuts to put floor inside though i would have thought it was a better and much more proffesional job doing so. Ive got no cracks so far gonna crank it tommorrow and hope it holds.
cheers James

[david s]

Re: I'm getting closer to my Dome!

Placing the dome over the floor might actually be worse because there will be no gap for the floor to expand to and the massive weight of the walls on the first course would prevent any movement between them and the floor bricks. This would result in stress build up at the base of the walls.Given that the safe recommendation for temp rise in pottery kilns is 100/Hr (and we all exceemd that by heaps) the best thing you can do is let the material expand more evenly by firing up more slowly, particularly at the start when the temp rise and resulting uneven expansion is so rapid.

[PizzaIdiot]

Re: I'm getting closer to my Dome!

David, I can understand the first part of what you wrote, as the oven floor heats up, but as it cools, the perimeter under the dome wall doesn't have to move with the floor - since the floor is not one solid piece. It may also be that small gaps between the bricks in the floor 'abosrb' some of the expansion of the bricks during the heating.
I still have to figure out which way I'm going to do mine.
Jeff

[Cheesesteak]

Re: I'm getting closer to my Dome!

John -

I'd probably try to grind out some of the mortar where the cracks are - and use some homebrew and firebrick shims to re-seal. Do you have a decent grinding wheel? You might even want to try something like a dremmel to get that done.

Good luck - and it looks like Irene's degrading - so hopefully you're okay there.

[Evets]

Re: I'm getting closer to my Dome!

FWIW, I built my dome on the floor and after a year, have no cracks in the dome.
As for Irene, my oven sits about 100 ft. from a small stream bordering my property. At 4AM today it was only about 15 ft from the waters edge.
It's all better now though.
I hope you're not getting pounded too badly.

[david s]

Re: I'm getting closer to my Dome!

David, I can understand the first part of what you wrote, as the oven floor heats up, but as it cools, the perimeter under the dome wall doesn't have to move with the floor - since the floor is not one solid piece. It may also be that small gaps between the bricks in the floor 'abosrb' some of the expansion of the bricks during the heating.
I still have to figure out which way I'm going to do mine.
Jeff

Floor movement iis reduced iif The sand/fireclay leveling mix is placed wet rather than dry.The whole oven, floor and dome are in motion and the last parts to heat up are the dome perimeter. When the oven is new and full of moisture the problem is exacerbated because the moisture at the bottom of the dome is the last to leave and it keeps that part cooler for longer creating more temp difference and resulting uneven expansion.

[Aegis]

Re: I'm getting closer to my Dome!

We are safe and sound here in southbury, using a borrowed generator for a couple of hours so this post will be the first and last till power is restored! I hope everyone else faired as well as we did, no trees in the living room and no indoor pool in the basement - Life is Good!
Cheers All!

[Aegis]

Re: I'm getting closer to my Dome!

Here are the side by side comparisons. I don't call this a crack, it is a fissure! I would think my gap was non-exsistent somewhere 90 perpendicular to the cracked area.
You can see the first pic the soldiers are touching then the next pic there is an 1/8 to 3/16" gap - oh my!
I am sure if you have a good gap between the hearth and the soldiers you will be fine. I did not and paid the price! Just beware of this pitfall.
As for the floor expanding and the weight of the oven on the hearth not allowing it to expand, well something has got to either give or break! If the floor does not move then I would imagine spalling due to compression forces from the hearth bricks expanding would take place. If they did in fact expand under the dome bricks from the heat and expansion forces, what will move them back during the cooling cycle? Will they just hang out and you will have large gaps between hearth bricks? As I am well past this point I am asking for my own selfish knowledge and maybe someone else could benefit from it who hasn't set there hearth.
Last pic is my wifes idea of taking a pic of a crack in the dome!

[woodfried]

Re: I'm getting closer to my Dome!

Thats wierd the joint has moved on the rh side so much it looks like the 1st row brick has been removed and cut smaller or shrunk if you look at the perp joints relative to the soldiers before and after, while the lh joint remains the same Or was 1st pic taken whilst 1st course was laid out and not mortared . Anyway not the end of the world
Cheers

[Aegis]

Re: I'm getting closer to my Dome!

Thats wierd the joint has moved on the rh side so much it looks like the 1st row brick has been removed and cut smaller or shrunk if you look at the perp joints relative to the soldiers before and after, while the lh joint remains the same Or was 1st pic taken whilst 1st course was laid out and not mortared . Anyway not the end of the world
Cheers

I added a pic with the next two courses mortared. The soldiers were mortared in the first pic.
I did grind out on the outside and was able to remove mortar wedge between the two soliders. I then did as Brickie suggested, with the oven warm I put a slurry of heatstop in and then put in a wedge of firebrick which made the joint quite tight. I did the similar for the upper cracks although the mortar was not removed. I still had room for some small pieces of firebrick to insert. I then covered over the rest with the left over slurry. Today I went back inside the oven and filled in the gaps from the inside as the slurry did not make it all the way through from the outside. I used a premixed product that is tan in color and it seems to have a very sticky consistancy to it. It went on nicely and I wiped off the excess. I am a rather large person and to get in to reach the back with any sucess was a real feat by itself!
I will start some curing fires again next week and will see what transpires.

[Aegis]

Re: I'm getting closer to my Dome!

Here are a couple of pics of the crack repair. I guess I'll have to wait a week or so to cure the repair and start oven curing all over again! I still have a ton of finish work to do which, from here on in I do not have a good plan. I have a plan, but it is more in general terms rather than drawn out on sketch up. I got a couple of huge pieces of marble for a counter top. It is 2 inches thick and came in two pieces, so I used two levels to extend across the pad. Hey for fifty bucks I couldn't pass it by!

[PizzaIdiot]

Re: I'm getting closer to my Dome!

The repair looks good - inside and out -although it's hard to see the outside!

I'm glad to know I'm not the only one who doesn't have the outside design finalized. Generically it's going to be stucco on top and rock on the bottom with a granite ledge in front, but I'm still trying to figure it out the details.

Jeff

[GianniFocaccia]

Re: I'm getting closer to my Dome!

Killer patchwork, John. You now have a 'character line' to go with those gorgeous countertops!
John