42" FB Pompeii Oven with 19" dome, and adjacent fireplace, in the O.C.

[dvm]

Very early in the process. Planning a side by side oven / fireplace. Install will bend then include a grill and small fridge to the right, pony wall (for seating) to the left. The back of the structures forms 1/2 the perimeter of my younger son's tortoise enclosure.
Let the games begin!

[brianventura]

Re: 42" FB Pompeii Oven with 19" dome, and adjacent fireplace, in the O.C.

Good luck with your project.

[dvm]

Re: 42" FB Pompeii Oven with 19" dome, and adjacent fireplace, in the O.C.

It was a good day. 2.5 yards of concrete pumped to the back yard and the waiting forms in about 10 minutes!
First major step... check

[deejayoh]

Re: 42" FB Pompeii Oven with 19" dome, and adjacent fireplace, in the O.C.

Looking good!

I'm in the midst of building a 39" Pompeii with an 18" dome - dimesion wise, it is pretty similar to what you are planning. I can tell you from experience that there are some additional challenges to the low dome shape. Namely, you can't use an IT if you want a true arch, as the radius of your dome shape will be greater than the radius of your oven footprint. If you want any pointers on potential pitfalls (I don't claim to have best practice insights) give me a shout.

[dvm]

Re: 42" FB Pompeii Oven with 19" dome, and adjacent fireplace, in the O.C.

Hello deejayoh

I am always looking for advice! My current plan is this: I used a large sheet of butcher paper to draw out the profile of the oven in cross section. My cooking floor will be the large FB tiles (2 inches thick). To increase the thermal mass below, I will cut fire bricks in half to make splits and put this layer below the larger 2" thick tiles (so the floor thickness will be a total of 3 1/4 inches). I plan to use a row of full brick soldiers - tapered at the top - around (not on) the 42 inch diameter floor. The interior of the dome height will be 19 inches - this works out to 10 courses above the soldiers and a cap stone (we shall see).

The radius of the dome arc originates below the floor (on the drawing) making the application of an IT challenging. My plan (untried) is this: For each course I will removed the IT from the project and use the full size drawing to re-set the tool for the next course. I will adjust the length (it is wood - cut it shorter) and adjust the angle of the bracket holding the brick (shims and clamps) for each course.

What do you think?

[deejayoh]

Re: 42" FB Pompeii Oven with 19" dome, and adjacent fireplace, in the O.C.

DVM -
your plan sounds good in terms of having the layout all done, and you've tumbled to the problem that it took me a while to figure out - the radius of the dome is > the radius of the floor.

On the IT, I think the approach you are considering will work. It may be bit of effort - but it should keep you on track. One thing to consider: as you point out, the angle of each chain to the IT will be slightly different because you are not pivoting off the "true" center of your dome. To be 100% accurate, I think you'd need to start with the IT mounted a bit off center and then with each consecutive chain, you would need to move it in toward the center to approximate the angle you would have from the center.

An alternative approach that I wish I would have done (which would take care of the problem above) is to use an improved version of the plywood form I used (see picture). The modification I am thinking about is to :
1) Use a plywood form mounted to spin from the center, but cut the form with a radius about 1" shy of the actual dome radius that you want
2) Before you cut out the form, mark the angles for each chain (before you cut it because otw you may lose track of where the center was like I did!) So you'd draw the quarter round shape on a piece of plywood, and keeping your pin in the center (assuming you're using a piece of string), draw a line for the top angle of each chain.
3) Fill in the gap between the form and your dome with a short "IT" made out of a piece of 1"x2" wood + a metal bracket that extends 1" from your form (to make up the radius). For each chain, line it up with your markings and screw into the plywood. If you want to make it even more useable, figure out a way that the short IT can flip up and down in order to drop it onto the brick to check your work. Might be as simple as drilling it for a nut and bolt.

I think this has a couple of advantages over what I did
1) A full sized plywood dome form catches on small mistakes you make as you rotate it in the dome. This makes you not want to use it . By making it a little smaller, it will be easier to rotate
2) Marking all the angles at the start lets you build exactly what you planned, instead of checking each row and figuring out the rest of them like I've been doing. tip: write down the angle of each row, you can use it to cut a jig (if you are using hendo's technique)

Might also be easier than what you are thinking about in that you have all your dimensions laid out at the beginning.

One last thought: In my experience, you don't need a clamp on your IT. Just my $0.02, but I am not sure what people do with those. The bricks take a bit of wiggling to get them in place and I'd think that a clamp would get in the way of applying that "english". Also, if your mortar is the right consistency, once the bricks are set they don't really need to be held in place. I'm at the 11th chain (I didn't use a soldier course so I have lots of chains) and the bricks don't need any support @ 70 degree angle.

(wow - I just wrote a novel here. Hope it is useful!)

Dennis

[dvm]

Re: 42" FB Pompeii Oven with 19" dome, and adjacent fireplace, in the O.C.

I like the idea of a solid plywood template cut to the profile of the dome with each course of bricks marked out that can rotate on a lazy susan. Not sure I am picturing how to cut it one inch small and then bridge the distance with a 1 Inch "IT".

[zdziandy]

Re: 42" FB Pompeii Oven with 19" dome, and adjacent fireplace, in the O.C.

I'll be reading this thread with interest as i am very much a novice and just starting on a similar project 42" Pompeii Oven with the "High Vault" which they describe as 18" inside height so I assume that is the dome height. Only in the base building stage so still some time away from getting into the dome but I am preparing for it!! Pardon my ignorance but what is meant by "IT". I also assume that once the dome is complete the plywood dome form can easily come out through the entrance. I look forward to further tips and thank you.

[deejayoh]

Re: 42" FB Pompeii Oven with 19" dome, and adjacent fireplace, in the O.C.

I have a sketchup somewhere that I made for my intial idea. I'll look for it and try to mod to show what I mean when I have a little time this afternoon

Edit: Here is a rather quick attempt to show what I mean. The darker piece of wood is the plywood form, and the lighter piece of wood is what I was calling the IT in that it's the actual guide for the angle and height of the bricks as you lay them. The dome shape is the light blue area. So the "IT" is a short piece of wood with a bracket on the end that can be moved from chain to chain to help you keep everything both level and on track.

I didn't do a very good job of drawing a bracket on it because sketchup was giving me hell, but hopefully this conveys what I was thinking.

The more I think about this, the more I wish I had done it this way!

[brianventura]

Re: 42" FB Pompeii Oven with 19" dome, and adjacent fireplace, in the O.C.

dvm,
I built my oven with the soldier course and used the plywood method. It worked well for me but I did not fix the board to the floor, all I did is mark the floor center and had the center mark on the edge of the board and went around setting the brick. That way I was able to take it in and out easier initially. For the last chains I made a form were I set the chains on top of.

Attached you can see the board inside the oven (the only photo I have of the board). Also the form I made for the last chains.

Brian

[deejayoh]

Re: 42" FB Pompeii Oven with 19" dome, and adjacent fireplace, in the O.C.

I'll be reading this thread with interest as i am very much a novice and just starting on a similar project 42" Pompeii Oven with the "High Vault" which they describe as 18" inside height so I assume that is the dome height. Only in the base building stage so still some time away from getting into the dome but I am preparing for it!! Pardon my ignorance but what is meant by "IT". I also assume that once the dome is complete the plywood dome form can easily come out through the entrance. I look forward to further tips and thank you.

Welcome! You are definitely in the right place for info. If you've started on your build, please start a thread and share! Pictures pictures pictures!

IT = "Indispensible Tool". Do a search for it, but basically it is an arm mounted in the center of the dome that lets you check the bricks for angle and distance from center as you install them. The catch is, it only works well if you are building a perfect half sphere

Vault - I would call an 18" dome height in a 42" oven a low dome oven (versus a sphere as referred to above, which would have a 21" dome height). You'll definitely need some sort of form for that

Getting the form out of the oven - yes, as long as your door about the same width as your form is tall - which it generally would be. But you can always burn it if you have a problem!

[Gulf]

Re: 42" FB Pompeii Oven with 19" dome, and adjacent fireplace, in the O.C.

About the IT: I did not adjust if myself, stayed with the sphere. However, I do believe that if you really want to lower the dome using the IT, an adjustable IT would be the route to go. I had planned to lower mine but, decided to leave well enough alone as I got into it .
I used a large turnbuckle.

My plan was to wait until I cleared the inner arch before beginning the adjustments. (My inner arch and it's protrusion into the dome was guaged to the IT @44") In my case I did not think there were enough rows left after clearing the arch to get to a low ceiling heighth.
Someone with some experince with marrying the low dome with the inner arch may can help but, I think that an adjustable IT would be the Key.
Just Sayin'

[dvm]

Re: 42" FB Pompeii Oven with 19" dome, and adjacent fireplace, in the O.C.

zdziandy
Welcome to the forums. I have been reading them for months and I discovered that IT refers to an Indispensable Tool. You can search the forums and find several threads describing variations on the "IT" with photos and instructions for construction. Like here http://www.fornobravo.com/forum/f28/...heme-2985.html
If you were making a 42 inch diameter oven (with a floor radius of 21 inches) and a "High Dome" (with a height of 21 inches) the IT could pivot from the center of the floor and align the bricks for each row in the dome. Deejayoh and I are discussing a means to modify the "IT" for a low dome application - the catch is that with a 42 inch diameter and a low dome (in my case 19 inch - though 15.5 inch has been described!) a simple radius will not work.

[dvm]

Re: 42" FB Pompeii Oven with 19" dome, and adjacent fireplace, in the O.C.

DeeJayOh
AhhHaa I see what you mean. Thanks for the sketch-up diagram. I was also interested to hear that you don't think that a Clamp is needed to hold the brick in place with the IT. I have not place one brick yet... But I expected that securing the interior face of the brick at the desired angle and holding it there would be difficult and achieved by rigidly clamping with the IT.

[dvm]

Re: 42" FB Pompeii Oven with 19" dome, and adjacent fireplace, in the O.C.

brianventura
I like the simplicity (function!) of the plywood template. Aside from having the bricks touch the wooded guide, was it difficult (necessary?) to determine the angle of the "oven" face of each row of brick - I am trying to understand if the "clamp to the desired angle" feature of the IT is and important feature lost using your method. Forgive me if this is a dumb question - I have not yet placed one brick. (But I will be building my stand this long weekend).