I'm getting closer to my Dome!

[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.

[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.

[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.

[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

[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.

[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

[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

[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!

John,
Congratulations (on curing stage) and regrets (on the crack).

So you did have a gap between your floor and soldiers? How big was it? 1/4" or more? I don't remember what the suggestion is. (I used a double thickness of corrugated box strips) but you think a brick chip got in there?

I only had 1/8" gap around and I am sure I had some construction debris in the gap, probably in more than one spot. I looked back at the pics of that area 4 months BC (before crack lol) and the soldiers brick edges touched without mortar showing. So something,or somehow not only did mortar crack but the bricks physically moved at that point almost 1/8" apart! Had to be some extreme force to move the bricks apart.

Al's suggestion of mortaring with slurry while it's warm is the first I've heard of. Sounds like a sound plan. No matter how you repair it, you'll probably always see a hairline crack (or re-crack) but once you insulate on the outside your dome will function like normal.

I have actually been able to remove the mortar between those two bricks and clean it out so to speak. I will replace the old wedge of mortar with a slice of pizza.. oh I mean firebrick. Can you tell I can't wait to get cooking! LOL With the firebrick I will use a loose mortar and then continue up the "crack" till it is as closed as I can get it. Since the crack it now a cavern, I am not sure have a warm oven is needed but I guess that it will contract on the mortar and make a tight seal. Al is that the theory behind your suggestion?

So close to being done, this small setback will be over soon. Good luck on getting thru the hurricane. If your oven survived your earthquake this week and the hurricane tomorrow, this crack is the least of your problems

-Dino

I have it all wrapped up in tarp for Irene so I cannot take pics of it after grinding, but here are two pics showing before and after. I am fine with the repair and set back although when it happened it was demoralizing.
Thanks for the support, kind words and most of all the help your build has given me.
Thanks
John

[Dino_Pizza]

Re: I'm getting closer to my Dome!

John,
Congratulations (on curing stage) and regrets (on the crack).

So you did have a gap between your floor and soldiers? How big was it? 1/4" or more? I don't remember what the suggestion is. (I used a double thickness of corrugated box strips) but you think a brick chip got in there? I bet that happens more than we think. I vacuumed the heck out of my floor edge but it is difficult to get the vacuum head to the rear edge and that's where your crack happened.

Al's suggestion of mortaring with slurry while it's warm is the first I've heard of. Sounds like a sound plan. No matter how you repair it, you'll probably always see a hairline crack (or re-crack) but once you insulate on the outside your dome will function like normal.

So close to being done, this small setback will be over soon. Good luck on getting thru the hurricane. If your oven survived your earthquake this week and the hurricane tomorrow, this crack is the least of your problems

-Dino

[Aegis]

Re: I'm getting closer to my Dome!

Hi Mate , that sux about the crack im sure it will be an easy fix.
Is that Hurricane Irene your are talking about? just had a look on internet !
cheers James

Yep, Good Night Irene good night Irene I'll see you in my oven! lol

I hope the crack will be an easy fix and it will be a good opportunity to fix it and let it set for awhile to let Irene pass!
Thanks John

[woodfried]

Re: I'm getting closer to my Dome!

Hi Mate , that sux about the crack im sure it will be an easy fix.
Is that Hurricane Irene your are talking about? just had a look on internet !
cheers James

[Aegis]

Re: I'm getting closer to my Dome!

Well as I am waiting for some heatstop to be delivered I finished curing the oven. I am pleased to report the next fires were totally uneventful. I did go back theory my pics and the soldiers were all tightly spaced, as in no mortar gaps. Which again leeds me to believe I had something between the firebrick hearth and the soldiers. Now I will start on repairs and hope the hurricane doesn't take it away ! Lol

[Aegis]

Re: I'm getting closer to my Dome!

Do both at the same time just dont play the Devil while doing it and keep the fires small.

Thanks Al, your the best! (if this works that is!)
Thanks
John

[brickie in oz]

Re: I'm getting closer to my Dome!

Thanks a ton for the translation and help. One other question: Should I try to finish curing the oven before repairing or wait until after repair(s)

Do both at the same time just dont play the Devil while doing it and keep the fires small.