OctoForno

[garch]

Re: OctoForno

Thanks John, I picked up some board yesterday after reading your input. I found a local dealer who carried the product.

This gentleman was telling me that the outside of the dome would need to be anchored to the structural hearth, otherwise the dome will collapse over time. I dont remember anybody with that complaint, your thoughts?

Thanks again

Gregg

[dmun]

Re: OctoForno

This gentleman was telling me that the outside of the dome would need to be anchored to the structural hearth, otherwise the dome will collapse over time.

Over time? Like in thousands of years? It's quite possible. For our lifetimes? Unless your dome in on a trailer on the public roadways all the forces are down. As the riggers say, gravity always wins.

Any method of anchoring the dome to the structural slab will create thermal bridging that will be a lot more of a threat to pizza than imaginary sideways forces.

Insblock19 is pretty water resistant. My build was partly open for the better part of a year, and I didn't notice any degradation of the block.

[GianniFocaccia]

Re: OctoForno

Gregg,
The oven floor and dome rest directly upon your insulation layer regardless of whether the first course has been built on top of or around the floor. Like dmun says, any direct contact of the dome with the structural layer will leak continuous heat through conductivity, requiring an inordinate amount of fuel to reach and maintain pizza temps, not to mention greatly shortening your retained heat curve.

John

[garch]

Re: OctoForno

Thanks John and Dmun.

Your input really helps, I really thought that this gentleman was wrong, but I feel much better with both of your input. Bought my HF saw yesterday, a week of vacation and on to the dome. Thanks again,

Gregg

[Mistertoy]

Re: OctoForno

Hi John

I have been reading the posts by yourself and ggoose (Gene) about the arch transition.... I am aiming to do a that sort of transition to avoid the upsidedown "v" with my nearly 36" pompeii oven.

I have 3 bricks high (75mm bricks) straight sides on the entry with a arch of tapered bricks. I am struggling to work out the downward and upward tapers on the inside of the dome. I have done some work with the indispensable tools but it is not clicking with me.

The way I am thinking at the moment, as a point of reference I need to extend the arch bricks into the dome so the highest centre brick lines up with bottom edge of the row of brick that join above the arch otherwise I will have a v gap... If I have this point maybe I can work back from this point. Not sure if that makes sense. am on on the right track ?

Any additional help or hints would be appreciated.

Thanks
Brett

[GianniFocaccia]

Re: OctoForno

Brett,

I know right where you are in trying to visualize your arch config. Here's how I did it.

Make a (36"?) template out of plywood to match the curvature of your dome. If you're using an IT it will be easy. Then measure the distance from your floor center to the inside of your inner arch. Cut your dome template (vertically) this same distance so it will fit flush up against the inside of your inner arch form. (see photo below).

Start your arch by cutting the center-top brick. Use your indispensible tool (or a piece of string) to figure out the upper angle. Use the profile of your dome template to figure out the lower angle. (OctoForno post #34). Once you have these angles figured out go ahead and cut the rest of your arch bricks, but only the tapers, not the inside radius. If your bricks are tapered this is one less step for you.

Once all your bricks are tapered and held in place with shims, scribe a line using your IT/string from the back of your center-top brick to the back of your last brick on either side where it meets the dome. This will give you the cut line for the inside of your arch.
Match the top and bottom angles from the center-top brick for each adjoining brick and you're there.

If this sounds confusing let me know and I'll sketch something up. Hope this helps.

John

[Mistertoy]

Re: OctoForno

Thanks for the instructions John...

I had done some of the steps before but it was not working out or clicking with me.

I have got it now ... I spent a bit of spare time on the weekend after your post working it out and marking out. Then I thought about it that night and I still had it wrong !
Had a re-look the next day and made up a few IT attachments to help marking out, did quite a bit of measuring against my plywoord template and decided tapered the outer bricks facing into the oven (rather have the whole inner surface of the arch straight) and I was now happy that I had it right.

Appreciate the advice... I am pretty confident it will work out nicely... time will tel, anyway too late now I have done the major cuts !

Picture attached - only the outer bricks to go which will be straight forward.

Brett

[GianniFocaccia]

Re: OctoForno

Brett,

I think you nailed it! Both the inward-facing and upward-facing planes look accurate and aligned correctly. I'm interested to see how you handle the arch bricks on the ends where they tie into the dome, but they shouyldn't be too difficult. The real benefit comes when you start to add the courses immediately above the arch.

Keep us 'posted'!

John

[mrchipster]

Re: OctoForno

The key for me in understanding this type of inner arch design was to understand that the slope of the cutoff for the top of the inner arch (the cut that will receive the dome bricks) is defined by the inner radius of the dome -- lower edge of brick, the outer radius of the dome - upper edge of brick, and the slope of the cut, as a vector from the center of the oven.

Chip

[GianniFocaccia]

Re: OctoForno

The key for me in understanding this type of inner arch design was to understand that the slope of the cutoff for the top of the inner arch (the cut that will receive the dome bricks) is defined by the inner radius of the dome

That was ridiculously well said...

[Aegis]

Re: OctoForno

I am VERY Jealous of your skill and technique, which my oven lacks immensely. I do wonder if the gorgeous transition will have the same structural values as a standard arch with dome bricks being placed on top of instead of dome bricks being set next to the arch bricks. It seems this maybe creating a thrust force perpendicular to this joint, which is perpendicular to the arch. I have some mechanical design background but as far as arches go, I have learned all I know from this oven build. So I maybe way off in left field, or it simply isn't a factor since the loads will be handled by the arch and dome anyways.
Again I AM Jealous!

[GianniFocaccia]

Re: OctoForno

It seems this maybe creating a thrust force perpendicular to this joint

John,

Thanks for the compliments. I think you're shortchanging yourself tho. Your build is very clean, competently constructed and I would have no problem with your oven if it was sitting in my backyard.

I too considered the side-thrust forces involved with modifying the dome-to-arch connection angles. After looking at it fourteen ways, I cocluded it was safe to proceed because:

1) Regardless of the connecting angles involved, the dome and arch brick mass remains the same. To me, this means any side-thrust is essentially identical in either transition approach. In reality I feel the transition is stronger because there are no 'hanging' dome bricks, the adjoining dome bricks are uniform with the rest of the dome, and this approach leaves no gaps in the interior oven surface.
2) A hemispherical arch is inherently stronger than a vertical-sided arch and this advantage carries forward to the adjoining entryway.

I'm no engineer, but I will tell you that my 'integrated' transition was fun to build and feels extremely strong and stable. That's my story and I'm sticking to it!

John

[Aegis]

Re: OctoForno

John,

I'm no engineer, but I will tell you that my 'integrated' transition was fun to build and feels extremely strong and stable. That's my story and I'm sticking to it!

John

Hi John,
Great story with wonderful pics and I would stick by it too!!!!

[GianniFocaccia]

Re: OctoForno

Well, I finally got the dome closed up today! It felt good to mortar in the required Octoplug. I feel like the end is finally in sight, although building the enclosure will take some time too.

I know this oven is taking a really long time to complete, but this summer has had the wife and I at (fri-sat-sun) swim meets half the weekends May through August. I'm pleased to report though, that my 16yo daughter has now qualified to swim at the 2012 Olympic Trials in Omaha next June, so whenever the oven gets completed will be soon enough.
John

[Mike D]

Re: OctoForno

Very nice John, very nice. I bet that felt fantastic to finish that dome.

Mike