Pizza History in the Hammer Continues

[david s]

Those air set mortars are designed for much higher temperatures than your oven will see. They require the high temperature to sinter the materials to make the mortar permanent. Consequently if used for a wood fired oven the material never gets hard enoug. Other builders have used similar products and found them unsuitable. Contact the manufacturer.

[Baza]

Chachdavid s you are on the money with the timbre of the forum.
I'm going to talk with my mate that owns the refractory business (where I go the pails) to see what he says - and other WFO pundits in S. Ontario.
The mass suggestion seems to be: if you can find Heat Stop 50 for a good price, go for it (simple); if not, mix the home-brew noted here on the forum (gulp).

Thank you both - I should know more tomorrow!
Barry

[Chach]

Its not hard to make the mortar. People get intimidated by the 3:1:1:1 formula all you need to do is get a container say 16oz and get a 5 gallon bucket with a lid. Fill the 16oz container with sand and pour it into the 5 gallon bucket 3 times and then fill the 16oz container with the lime fire clay and portland 1 time each and dump into the bucket. Put the lid on shake it like crazy wait a few seconds for the dust inside the bucket to settle and open walla perfectly mixed Ingredients. now mix yourself a little with water and start using. I used a 32oz container and did this and just took what I needed out of my 5 gallon bucket and closed the lid until I needed to mix more.

Ricky

[UtahBeehiver]

Heat stop is spendy,but if that is what you want to do, go for it. Homebrew is very easy and cheap as long and you can procure the raw materials, fire clay is the hardest, then lime, sand and cement relatively easy.

[Baza]

This is great tutelage! Thank you - I’m starting to lean this way. Saw an FB build by a person who’s step by step said to NEVER use a mortar with Portland cement as it breaks down over time in this environment - yet many here, including both of you Ricky and Russell, used it very successfully- here’s how newbies get spooked!

[Baza]

Laying out my template to being the cutting of the CF board and laying out floor:

Wondering - is it best practice to create a heat break b/w the oven and the landing?
If so - is the heat break usu. a ceramic rope? how thick? does mortar link the inner arch/rope with outer arch/landing?

I'm in an over-think stall right now - scared to move from all the ideas and cautions that I have to remember. Some build by feel, others by autoCAD, others still with both!
I'm thinking to layout what I want - then just make it work (based on great builds prior to this, to be fair).

Trying to shake off the "fear of moving forward"

anyway ... any help on the heat-break question above is welcome.
Barry

[RandyJ]

Yes a heat break is a great idea. You only need about. 25" or so roughly. I used a thick sheet of cardboard to create a even gap. Then what ever yoy find for ceramic roap that you can shove in to there. I think i used a .375" thick section for mine. Then sealed it with refractory culk on the inside and used vermicreete on the outside of it.

[Baza]

Yes a heat break is a great idea. You only need about. 25" or so roughly. I used a thick sheet of cardboard to create a even gap. Then what ever yoy find for ceramic roap that you can shove in to there. I think i used a .375" thick section for mine. Then sealed it with refractory culk on the inside and used vermicreete on the outside of it.

Thanks so much Randy!
Ok - you did that around the inner arch to separate it from the outer ... did you do so along the floor as well to separate the cooking floor from the landing floor?

[RandyJ]

Yes i did. I left a gap that was about the same as above. Then stuffed it with several rows of ceramic rope and then filled the rest of the gap with ash from the fires. Every little bit helps when trying to retain as much heat as possible.

Randy

[Baza]

UtahBeehiver coined a phrase "analysis paralysis" - I'm suffering ...
P3 Stoaker Grateful, too, for your questions re: the inner arch - they are mine too.mongota has been WONDERFUL in helping me understanding his arch design/architecture too.

The one nagging thing I have in order to lay out my floor plan for cutting the insulation board and designing the footprint of the oven is: how thick does the dome arch template have to be to be both structurally sound, provide an inner face for the angled brick in the dome and not eat up too much vent floor space?

I know where to place the inner face (I have a 42" build that will be hemispherical - I will be putting a 20" opening at the edges of the inner diameter of the oven). I'm planning to go up 3 bricks before angling the dome arch. I will be flaring the vent from the 20" dome arch opening to the 25" at the vent arch opening. But ...

I don't know how far to come out from the inner dome arch point into the vent.

Mongo suggested that after placing his template at the inner diameter placement, he measured a half-brick out into the vent area, then when cutting, placed the vent facing part of the brick flush with the template and marked the angled interior cuts from there. This left a 1/2 brick at the TDC point - quite thick - but great for thermal retention.
Others, Dino, had a 2.5" brick around the dome arch template - and his build is terrific too!

I just am looking for the sweet spot that affords the needs above, room for an 8" duravent chimney and a decent vent landing (with heat break).

Any simple answers to a long question so my paralysis goes away?

Humbly
Barry

[mongota]

With my dome arch being 4-1/2" thick, you can see in the first photo that the arch bricks at the base of the arch project maybe 1-1/2" out from outside face of the dome. As the arch goes up in height, the dome curves away from the dome arch, increasing the amount of projection. The projection reaches its maximum with the top dead center arch brick.

At the base of the dome arch, the bricks don't have to project out at all. That would allow you to have a "less thick" dome arch, possibly saving you a couple of inches in your footprint.

The reason I built the way I did was based on how I wanted my vent arch bricks to integrate with the dome arch bricks. I wanted my vent arch bricks to wrap around the front face and side of the dome arch bricks, but I did not want to mortar them together as I wanted them to move independent of one another. I used two lengths of ceramic fiber rope to 'seal that gap'. You can see that in the second photo.

There are indeed myriad ways to build. I probably overthought most aspects of the build. Then I overdesigned them. And then I overbuilt them. lol

But how I overthought, overdesigned, and overbuilt all made sense to me. So much comes down to how you will use the oven. More brick mass in the dome or less? More insulation in the build or less?

It might help to get a large piece of kraft paper and draw out a full scale drawing of your dome and dome arch. You'll see how they intersect. You'll see how far in to the dome center, as well as how far away from the dome center, the base of the dome arch can be, and how each of those positions will change the geometry of the bricks, and how the changes in brick geometry will affect the build. Especially at the top of the dome arch.

And don't worry...you're doing a good thing by thinking it through on paper. It's much easier to erase a pencil line now than to demo mortared bricks later. Figuring the dome/dome arch intersection was a curiosity to me. But once I FINALLY saw the geometry? Building it was the simplest thing to do. Seeing the bricks go up made the cut lines so easy to see. And it made me wonder what I was so worried about.

Good luck!

[Baza]

Mongo!
Always coming through! Your explanations are so clear! You should write an updated set of plans for these builds! I totally get the “why” of your decisions - which are key to making more independent decisions about one’s own build going forward (what is/isn’t going to work aesthetically or structurally)

THANK YOU!!
I have re-drawn my arch to be 4.5” thick because now it makes sense WHY and looking at your outer arch thickness it makes me comfortable as I was worried the thicker inner arch would leave too thin an outer arch. My measurements from a 4.5” inner arch thickness left roughly what your outer arch build looks like and that was a phew-moment!

plenty of room for the vent and chimney plate.
mall making sense.
cutting the floor plan and insulation today and get out of my paralysis!

THANK YOU AGAIN
Barry

[JRPizza]

Barry, there are two dimensions you need to work with. The outer face of the inner arch is set so that the dome and arch will intersect without having the need for the dome to go out of round and to avoid having the arch too far into the oven eating up floor space. Lots of posts on this but essentially you place a TDC brick on your arch form and make sure it will intersect the dome like the pic below. then the outboard face of the arch form sets the arch location. I also have cad drawings of this on my build thread. The second dimension is the distance from the outboard face of the inner arch to the outside face of the outer vent arch. I took Gulf 's advice and made my distance 1.5 bricks (13.5"). This gave me plenty of room/area for my 8" pipe and did not make my vent too deep so I could still work the oven well. If you don't do cad the paper layout is certainly the way to go. I actually did my cad layout then verified it with a big piece of cardboard just to check.

[Baza]

Hello Forno Friends!

Thank you so much JR and Mongo for your support, help and plain-talk insight. You have REALLY helped me.
As a result of this tutelage - I went back to my template - re-drew the arch to represent a 4.5" thick profile and adjusted my vent opening accordingly
JRPizza - it was REALLY helpful to know the measurements of your Vent floor distance! It helped me judge whether mine was in the ballpark (you made your adjustments according to Gulf's support).

I found my vent landing about half an inch shorter than yours (13" on mine) and given you said you had plenty of room at that layout for the chimney et al - I think the 1/2 inch won't make a difference to the design for the chimney flue (8" plate dimensions call for a 12" flange for the opening - this should work find ... particularly using Mongo's formed-brick design to do it!).

So the pics below show the outcome of that paralysis-solving support from you all.
HEAPS of THANKS my friends!
Barry
PS - today - laying the floor outline, drawing the floor and hopefully cutting the brick (if the weather improves! )

[Baza]

Oh - when laying out the floor - and knowing I'm putting in a heat break - should I account for that now?
Or - should I focus not the floor/arch cuts and, when doing the outer vent area - worry about that then ...?

I may have just answered my own question ...