#1  
Old 09-14-2013, 07:13 AM
Peasant
 
Join Date: Sep 2012
Location: Bergen NH - Netherlands
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Default "simple" idea for a buttress (neopolitan oven build)

Hello,

I plan to build a low dome oven. I thought of many things, bumped into many problems that others have also bumped in before me and a lot of the things I was able to solve, but on my quest, I had an idea for making a "buttress" wich I had not seen before. I am curious what others think about it and what kind of material (thickness) would be needed.

So I thought, lets share, maybe the idea is just plain stupid, maybe it's not and it might be usefull for others aswell. I thought about doing this because I was also thinking about steel cables to reinforce my dome.

The idea is simple. To reinforce the soldier course, how about using rebar and "folding" that around it.

See the picture. In blue and red I have rebar. I would say 6mm or 1/4 inch (that might be to small ?)

The rebar is bend around the soldier course. I thought about drilling a hole in the stones and put it in there nice and tight, but you could just as easily stick it between the stones.

In the picture, the rebar is bend around the soldier course. I don't know if you would still need to use reinforced cladding around it but that would make it fit tightly against the soldier course. Else you might have some space at some points but you could also fill that up with stones or iron. if you realy want to push the maximum out of the space you have, you could even consider freeing up some space inside the stones (with an angle grinder) and then use some mortar to go into it. This might even be stronger.....

I know there are other idea's for a buttress. My personal favorite so far is how Kiwipete did it with the steel entry and the steel cable tied to that. My problem, the steel door frame will cost me 325$. Second favorit is the solution by Tscarborough (barrel vault oven cladding) where he puts rebar into the floor and connects a steel cable to that. This will be the way I am probably going but my biggest problem with that solution is that I am somewhat afraid of the rebar leaking heat into my concrete slab. I have no space to put it into the firebrick floor. It is so close to the end of my floor brick that I am afraid it will break when drilling into it. Third favorite would be the reinforced mesh around the soldier course and then using 1inch to 3 inch of cladding like Stonecutter (Second course angle) discribes. Better safe than sorrow, I would be going for 3 inches wich makes my oven to big so I would have to make it smaller and it would also increase my thermall mass so much I do not realy like it.

Any thoughts apreciated. Thanks in advance !!
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Last edited by nachtwacht; 09-14-2013 at 07:18 AM.
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  #2  
Old 09-14-2013, 07:30 AM
Journeyman
 
Join Date: May 2009
Location: Detroit
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Default Re: "simple" idea for a buttress (neopolitan oven build)

In my opinion there are two issues with this plan.

1. The way you have the rebar bent into the soldier course will tear the oven apart due to the difference in thermal expansion between the brick and steel.

2. You will little actual support. Without a continuos ring the rebar will flex as the oven expand and not do much supporting.

If you want to do rebar use a continuos ring and weld it all together. I've built two of these ovens, and between the two tried multiple methods. In my opinion the simplest and best is a 1/4" thick continuos band of sheet metal.
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Old 09-14-2013, 07:44 AM
Peasant
 
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Default Re: "simple" idea for a buttress (neopolitan oven build)

Quote:
Originally Posted by shuboyje View Post
In my opinion the simplest and best is a 1/4" thick continuos band of sheet metal.
Yes, that is basicaly what I have seen how the Italian pro's do it. My problem would be that I do not have a welding machine. I could also not bend 1/4 inch sheet metal by the way... atleast not nicely.


The "tearing appart" was indeed also something I thought about that might happen but had no idea if it would indeed be a possibility.
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Old 09-14-2013, 07:49 AM
Journeyman
 
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Default Re: "simple" idea for a buttress (neopolitan oven build)

I think you could get away without welding.

Do multiple layers of thinner metal that is hand bendable, do lap joint with drilled and bolted connections. Use carraige bolts with the head on the inside to get as little clearance as possible.
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Old 09-14-2013, 08:00 AM
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Default Re: "simple" idea for a buttress (neopolitan oven build)





Note the brick are sailored, not soldiered, giving a final mass of 4", and the rebar end posts are drilled into the slab, the wire is in tension.
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Old 09-14-2013, 08:04 AM
Peasant
 
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Default Re: "simple" idea for a buttress (neopolitan oven build)

Understand....

but that means the soldiers will need to be higher than the hight of the door. If that would be the case (in my case I am thinking about 3 different designs where I have one that is indeed having higher soldiers than the door is) could you not also use a steel wire and "wrap" that around the dome two or three times ?

I have no idea how strong a steel wire would be. Maybe it is not strong enough ?

tia
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Old 09-14-2013, 08:23 AM
Peasant
 
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Default Re: "simple" idea for a buttress (neopolitan oven build)

Tscarborough, was it to show your idea more clearly (because I made a reference to it in my posting ) or you wanted to give it as an alternative ?

Because it is indeed my favorite idea to do it your way... The two things I do not realy like though is the fact that I have to drill into my slab and will get heat transfer into my slab and the added thermal mass....

Maybe I would not need to put such a thick layer of concrete over the steel band ? Maybe it is possible to use the steel band without the concrete ?

I can probably live with the heat transfer, I would prefer not to have to use the extra concrete. I have extra large bricks, allready 3inch thick and I am also using them sailor position. (soldier position would give me roughly 4.3 inch)

If it has to be, it has to be, how much as a minimum for concrete would you suggest using your steel band method ?

ps: since I assume the concrete is to "spread the force" somewhat, I also thought of the idea of putting steel plates between the steel band and the bricks. Maybe that could be a solution for not having to use to much concrete ?

tia !
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Old 09-14-2013, 08:41 AM
Journeyman
 
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Default Re: "simple" idea for a buttress (neopolitan oven build)

Quote:
Originally Posted by nachtwacht View Post
Understand....

but that means the soldiers will need to be higher than the hight of the door. If that would be the case (in my case I am thinking about 3 different designs where I have one that is indeed having higher soldiers than the door is) could you not also use a steel wire and "wrap" that around the dome two or three times ?

I have no idea how strong a steel wire would be. Maybe it is not strong enough ?

tia
It is my opinion that the soldier course should be the same height as the door. This allows you to build a complete dome without truncating it, eliminates the difficulty in building the transition, makes the build faster, gives better structural integrity, the list goes on and on.

As for the wire, been there done that, doesn't work. I built my first oven this way, 3 wraps of stainless wire. Problem is the wire is not one solid mass, it is instead lots of small wires bundled. The small wires cannot take the heat, and break one by one. When I demolished that oven to build my second oven every single stand of all three cables was broken.
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Old 09-14-2013, 08:59 AM
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Default Re: "simple" idea for a buttress (neopolitan oven build)

The amount of heat transfer is minuscule, and there is no added mass if you sailor the brick. The height works to advantage, as noted. The wire alone would do no good.
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Old 09-14-2013, 09:29 AM
Peasant
 
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Default Re: "simple" idea for a buttress (neopolitan oven build)

Thanks both. I allready am using a sailor course... since my bricks are fairly big, it is allready all the thermal mass that I wanted to have.

So just a wire is clearly no good, how much concrete would be the minimum you would want Tscarborough ? Would 1 inch be enough ?

tia
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