36" Pompeii in Indiana, US

[GreenViews]

Thanks Utah for your awesome help and prompt reply! I'm just trying to grasp this stuff correctly so I don't make stupid errors I regret or worse yet that cause significant problems with my build.

[UtahBeehiver]

I did not do a low dome so my IT concepts are based more on a full hemi sphere. I did not see how you could have the true arch radius point down in the insulation structure. Ideally the face of the brick should be perpendicular to the arch radius point as noted in your diagram 1, The second reason of the IT is ensure consistent brick tilt and diameter of the oven. If you can practically make the pivot point down in the insulation layer, have at it.

[GreenViews]

Aren't you doing a low dome? Then you will need and adjustable IT since the radius at the top is much small than at the floor. The critical items for an IT is that the line from the pivot point (make sure it is not offset from the center of the oven) along the IT rod the the "L" bracket intersects and mid point of the thickness of the brick. Second, the pivot point is at the floor elevation of the fire brick

Oh, I was assuming that the brick face should face the arch radius center rather than the center of the oven floor. Would not that be more traditional masonry arch? But no matter tradition if what is right for an oven build is the brick face toward the center of the floor. Having IT originate from center of floor and adjusting length for each course would be pretty simple versus what I thought I needed to do. But look at my drawing comparing the two and it becomes apparent that the brick face and therefore cuts between the bricks becomes most pronounced and significant midway up the arch. Is this a problems? It would change the physics between courses in the case of mortar failure, but I'm not sure if it is a good thing or a bad thing.

[UtahBeehiver]

Aren't you doing a low dome? Then you will need and adjustable IT since the radius at the top is much small than at the floor. The critical items for an IT is that the line from the pivot point (make sure it is not offset from the center of the oven) along the IT rod the the "L" bracket intersects and mid point of the thickness of the brick. Second, the pivot point is at the floor elevation of the fire brick

[Mongo]

Oven placement: Which is better? very close to edge of table or a few more inches back. With a few more inches back, I can still reach my hand just past the door without bending over. My oven base is higher than normal perhaps. It will be almost 8" higher than table so sternum level to me. Low dome 15" with 9.75" high door.

I strongly recommend the forward placement. You will want not only want to reach your door, but reach into the oven. My front arch is 8 inches from the front edge of my stand. I love the position. I can reach in and dump a load of charcoal from my 'mini chimney starter' into the center of the oven, then hand place kindling without bending at all.
Here's the front of my 42 inch oven with a 72" peel reaching all the way to the back of the oven. Should give you some perspective.

[GreenViews]

IT advice welcome: my Arch radius is below my floor and I've seen people do both of the following. Anyone have negative or positive experience to guide me in deciding to either:

a) Keep center bricks out of floor during build and make a single length IT or
b) make a complex IT that I change with each course?

[GreenViews]

The insulating fire brick I bought are Lynn Manufacturing IFB 2300F Rated lightweight ones. Maybe I couldn't put much weight on them, is that a question? I bought them on Amazon.com for a thermal break between the oven and entrance. Looking up specs, looks like 115 psi is modulus of rupture, with cold crush strength at 145 psi, so if I lay 3" angle iron across the 4.5" side, I have 14.5 sq inches, so I can safely stack 14.5 x 115 x number of places angle iron crosses top of brick. I was only thinking of putting one course of brick on top plus some clay flue liners and high temp cement (don't have final plans), but I think I have a lot of weight room for what I'm thinking of using for. I would leave space on each end of the angle iron to expand: not thinking of cementing them in, just floating material on top of them and outside the thermal break at that, but in the chimney which will get hot. Thanks JRPizza for your sketch!!! I had seen it somewhere it turns out and nice cad skills!!! In my drawings I show my opening just a little into my oven if I build my arch where the top of it intersects the dome on the lower corner of each which is what ijt looks like you were going for as well. I did want to cut back the front edge of my fire brick inside the oven to keep my chamber as large as possible and avoid corners for ashes to catch behind, but it seems there would be plenty of brick left over using halves for support.. but maybe I'll be safe and use 2/3 or 3/4 bricks rather than halves for the arch. I think anyway that the advice I'm getting is better safe than sorry over a miscalculation. I'll take it! Love the advice coming my way! Thanks! I just picked up some metal insect screen for under my CaSi board. I'm hoping to get weep holes drilled out today and if I'm lucky level and set my CaSi board.... but other chores to complete first, so let's see what I can do.

[JRPizza]

Can you tell us why you want to use "insul brick" as part of your vent support? Also as far as using a half brick for your inner arch - the arch needs to intersect the dome if you want to keep the dome round. There is some allowance in fore-aft location that can shorten or lengthen the distance from the center of the oven to the front of the vent arch so you should do some layouts to see how short you can make it and still work. If you look at the attached sketch of my oven you can see where I have some arch brick projecting from my dome at the bottom and more projecting from the top as the dome curves rearward. I could have moved the arch inward towards the centerline of the oven but wanted to maximize internal floor space. You can check out golfguiedo 's build - he's just starting and has his arch moved about as far inwards as practical. You have a few inches of in-out to play with, but you will certainly end up with more than a half brick for at least part of your inner arch.

https://community.fornobravo.com/forum/pizza-oven-design-and-installation/pompeii-oven-construction/422716-dreaming-of-oven-for-many-years-now-want-to-start#post422716

[GreenViews]

Oven placement: Which is better? very close to edge of table or a few more inches back. With a few more inches back, I can still reach my hand just past the door without bending over. My oven base is higher than normal perhaps. It will be almost 8" higher than table so sternum level to me. Low dome 15" with 9.75" high door.

[UtahBeehiver]

Just leave whole, the point is to raise the CaSi off the concrete hearth. 3/8 - 1/2" 3 or 4 then silicon some wire mesh on the bottom side to keep bugs out.

[GreenViews]

I have some used 12" porceline tiles from my last kitchen remodel which I decided I don't have a use for. Should I break smaller? What size weep holes are you using and how far apart?

[UtahBeehiver]

spaced out ungrouted tiles have been used by other builders where the spaces channel to the weep holes. Just the cheapest tiles you can find would work.

[GreenViews]

To keep opening tighter, I'm considering just a half brick wide inner door arch followed by a half to full wide insul brick for thermal break and flue opening area followed by decorative outside face. My question is those of you who have used half brick door arch, Do you find it adequate? My drawings seem to suggest it could meet up nicely with my low dome with enough brick left over for durability. Your experience? Do you wish you used more brick? I'm also not thinking about the possible need to keep any moisture from the CaSi board... raised a question above. set on tight ungrouted tile mesh? drill drain holes through concrete? I do have a very small slope on the top away from patio which I will need to address. tapering mortar layer under CaSi or under the tile mesh supporting it if I go that route? Very open to your thoughts on any of this. Getting excited about being able to start in earnest soon!

[GreenViews]

Great ideas on the clean water bucket and dirty water buckets! Just poured table last night. Soon will start adding curing wood under it and be able to start mock layouts. I suppose I should build a canopy over work area to keep rain off of project?? Also, draining of CaSi board... maybe place on checkerboard ungrouted tiles to allow draining underneath? Finally, the entrance arch. I'm thinking of making out of half brick rather than full brick to give me room for half insulating brick setback next and a lower profile opening. My drawings seem to suggest this might be enough material for the arch, but any experience here?

[JRPizza]

The clean water bucket is good advice. I actually used two buckets - one at the saw end that I filled with clean water, and one at the opposite end that I placed under the drain hole (didn't use the plug) to catch the dirty water. I cut so slow that my tray was filling up with water and dumping a tippy tray without getting wet feet was problematic. The dirty water bucket did the trick.