Share your crack stories

[brickie in oz]

Re: Share your crack stories

Building the oven and cutting the floor to fit inside is in my opinion all wrong and a waste of time, no one in their life time is going to replace a hearth brick, then there is the danger of something getting stuck in the gap and forcing the oven out as it expands.

Building the oven on the floor makes sense as it all expands and contracts at the same rate, if there is a difference it will be so small that you would need a micrometer to measure the difference.

[Bacterium]

Re: Share your crack stories

Point taken brickie.......

so for those out there who have built the floor inside, rather than underneath, how much cracking seem to have occurred.

[brickie in oz]

Re: Share your crack stories

Point taken brickie.......

so for those out there who have built the floor inside, rather than underneath, how much cracking seem to have occurred.

Maybe we need a poll thread to see?

[Bacterium]

Re: Share your crack stories

I actually tend to favour your position
But
What about when you have the floor all the way out and you have all that weight sitting on top. Even thought the dome is "free floating" does the dome actually float.
Meaning does all that weight of the dome prevent the bottom course expanding outwards.

[brickie in oz]

Re: Share your crack stories

I actually tend to favour your position
But
What about when you have the floor all the way out and you have all that weight sitting on top. Even thought the dome is "free floating" does the dome actually float.
Meaning does all that weight of the dome prevent the bottom course expanding outwards.

I believe that having the weight of the oven sitting on the hearth spreads the weight a little more evenly than the oven just sitting on the insulation, the insulation, which ever you choose to use is soft and spongy.

I really doubt that any dome floats assuming 300 bricks at 3kgs each.
Thats a lot of mass pushing down on a spongy insulation.
Spread that weight around a little on the hearth.

[brickie in oz]

Re: Share your crack stories

my consultant geologist classified as "silty clay"?

He is a genius, but wait, isnt all clay silty clay?
I hope you didnt pay him?

[Bacterium]

Re: Share your crack stories

Interesting discussion.....once I find pics of my old oven I can poll.

The other thing if its sitting on soft and spongy insulation brickie......could that be a good thing in actually allowing for movement????

[david s]

Re: Share your crack stories

So far, none that I can see. Maybe, if I let my imagination run wild, I can see some hairline cracks where mortar has released from bricks on one side of a join, but I ridgey didge am not actually sure about that. Some days I reckon I can see 'em, some days I reckon I can't.
It certainly isn't like some poor unfortunates who can insert a matchstick in their dome cracks.
The only crack I can see for sure is in the inner arch about halfway up one side it looks like the mortar has released from the brick on one side of a mortared joint.
And, hot or cold, that crack can genuinely be classified as "hairline".
I find myself wondering how this came to be. No fire brick, no fire clay, no specialist mortar, sailor course mortared to the slab, mix and match bricks, rather fast "curing" schedule.
Is it that I rendered the outside of the dome with a high lime, chicken wire reinforced 1 inch layer?
Is it that the dome is only 750mm internal diameter.
Is it that I couldn't find an affordable source of fire clay and used my own natural clay that my consultant geologist classified as "silty clay"? (It was the freight that killed every option I explored.)
Or is it, as I suspect, pure arse, as we say in Oz?

Could be all of those, but probably mostly the last option.

[stonecutter]

Re: Share your crack stories

So far, none that I can see. Maybe, if I let my imagination run wild, I can see some hairline cracks where mortar has released from bricks on one side of a join, but I ridgey didge am not actually sure about that. Some days I reckon I can see 'em, some days I reckon I can't.
It certainly isn't like some poor unfortunates who can insert a matchstick in their dome cracks.
The only crack I can see for sure is in the inner arch about halfway up one side it looks like the mortar has released from the brick on one side of a mortared joint.
And, hot or cold, that crack can genuinely be classified as "hairline".
I find myself wondering how this came to be. No fire brick, no fire clay, no specialist mortar, sailor course mortared to the slab, mix and match bricks, rather fast "curing" schedule.
Is it that I rendered the outside of the dome with a high lime, chicken wire reinforced 1 inch layer?
Is it that the dome is only 750mm internal diameter.
Is it that I couldn't find an affordable source of fire clay and used my own natural clay that my consultant geologist classified as "silty clay"? (It was the freight that killed every option I explored.)

Interesting...how old is the oven?

I feel that your reinforced cladding is what is keeping the sailor course from failing. I'm assuming you are only one wythe for your sailor course.

As a side point, good for you for pushing forward and building the oven with what you have.

[deejayoh]

Re: Share your crack stories

Wot - I think you mean stretcher course, not sailor course - to the picture that Brickie posted a while back? Half bricks laid with a 4.5" W x 2.5" tall face into the oven?

Do I have this term right?

[cobblerdave]

Re: Share your crack stories

Gudday
All the courses in the dome are technically stretcher courses of course. What makes them a sailor is the lower 2 (or 3?) are layed so to form a vertical wall the next courses are curved to meet a the top of the dome.
This is done to give more useable space alongside the dome walls on a smaller lower domed oven. A bigger dia oven with a higher dome would have a larger angle making this less a requirement.
I will take correction on this but I think this covers it


Regards Dave

[stonecutter]

Re: Share your crack stories

What makes them a sailor is the lower 2 (or 3?) are layed so to form a vertical wall the next courses are curved to meet a the top of the dome..

Vertical wall yes, but what makes a sailor course very,very weak is because the vertically oriented brick are laid with the width facing the inside diameter. The line of thrust of the dome arch exits high up on the back of the brick and lateral pressure is even worse the lower a dome gets. This also happens with soldier courses on large domes. Thus the need for buttressing, reinforced cladding or banding to keep the base course from being pushing out, causing the dome to fail.

[brickie in oz]

Re: Share your crack stories

Gudday
All the courses in the dome are technically stretcher courses of course.

They are all header courses in domes.
My oven was laid stretcher bond.

Here is a pic of it in its curing phase......

[cobblerdave]

Re: Share your crack stories

Gudday
Gentlemen ....I asked for correction and it was forth coming from the two most eminent in this field.....

Your health....
Regards dave

[CoyoteVB]

Re: Share your crack stories

Great discussion. Just fired the oven 2 days in a row. After 24 hours the oven is still 450F. Needs to cool a little more for Pulled Pork. The cracks seem to be stable My guest had no idea there was a crack in between the bricks.