Fnbrokens Corner WFO in Canberra, Australia

[fnbroken]

Extra course of brick on top of outer vent (total 3 x 50mm), with 'tapering' cutout (silver bit) that I will do to align the top of the serpentine arch to the diameter of the flue - hopefully ensure smooth flow of gases... I will also bull nose the bricks forming the inner arch of the outer vent going up into this area...

[fnbroken]

Sweet, thanks.

Re: doors. I've been looking at what can be cooked in the oven if the heat can be retained. Once I get a handle on that, and if it's likely something I will want to do, then this will probably drive the insulation requirements of the door. Will probably do like most and start simple and upgrade with time as required. It's really the core bits (those that cannot be upgraded easily later) that I want to spend the time and money on getting right now.

[UtahBeehiver]

I understand now, we are talking about the inner and outer arch sizes. 70mm revel will work fine. The outer vent arch just needs to be bigger than the outside size of the door frame so you and get it out.

BTW, Only if you want to install door stops, but they are typically self standing. The thicker the door the heavier it is so there are trade offs. Mine is on the thinner side at 1.5" with CaSi board inside. Some are going 3-4" for more insulation purposes but they tend to get heavy.

[fnbroken]

Cool, thanks Russell.

My inner vent has a 500m width, the outer vent is 680mm providing a reveal of 70mm between the two.

Is this either enough? Or too much?

I played with putting an extra course in, and it looks better so will have 2x50mm courses on top. Looking back, I notice that the holes in the lower course have been tapered to make it even smoother. Will do the same...

[UtahBeehiver]

Greg,

Q1 - Not sure what you mean by inner and outer vent.
Q2 - Smoke takes the path of least resistance so the smoother the transition the better. But your design looks pretty smooth. Square area effectiveness of a square or rectangular vent is not as good as a round vent so the as your design shows the lower part of the vent area is bigger than your round adapter plate hole so good there.
Q3 - The top brick, IMHO, over the anchor plate are both decorative and structural. The chimney is not terribly tall but wind load is a consideration since the build is open dome.I only had one course of bricks over my anchor plate, I think JR had the same.

[fnbroken]

oops...pictures attached...

[fnbroken]

A couple vent queries if I may...

1. Is there an optimal inner vent to outer vent radius ratio?

2. How much of a transition between the top of the outer vent and into the flue diameter is required? I recognise that the surface area of the vent needs to be greater than the flue - however does it need to be tapered at all? In the picture below, I essentially have it sitting flat on top of the serpentine arch... Note: the serpentine arch depth is the same as the flue diameter - 200mm.

3. If the flue base plate is bolted to the top of the arch - how important is it having more bricks on top of the base plate? Are they then just decorative? Or is more weight required to ensure it stays put?

[fnbroken]

My bad - it was Gulf's build...

[JRPizza]

I was checking out the "show us your door thread" and I think there are a few 4" doors, so mine won't be the thickest. I'm looking to use the door to hold heat after firing and between cooking, and make a lighter weight single handle door to use when the oven is in use.
I have not seen Russell's "light door", where did you see it?

[fnbroken]

Thanks John, 4" - that's deep! Will keep on eye on that one and see how much difference it makes.

Undecided on the build - I'm thinking if I can spec this all really well in CAD and have a number of stainless steel components to be made, I may be able to get a good price to have all the bits made (CNC) and shipped to me - I just assemble. I also have a welder and access to materials - so may go that option as well (although Ive never welded stainless and even my steel work leaves something to be desired lol - the last time I used it i blew holes in the metal and 6 weeks later it fell apart). The wood front and glass windows are also a great touch I want to explore.. so many options...

I like Russell's thin black steel door with the face cut into it - so you can see the flames licking behind it - I want one of those too...

[JRPizza]

Great work! I think the 1 meter/39" size just works well for symmetry with standard brick and material sizes. It will be fun to watch your oven "grow" from the ground up and see how it follows your plans. I found the model helpful when I needed to make small changes and could quickly mock up different configurations to see how they would look and fit.
PS, I'm building a 4" thick door (hopefully work a little after the UW Husky football game) and will post some build pics. Did you say you were going to hire out the build of your door or are you going to fab one yourself?

[fnbroken]

Last thing for the evening - brick cuts required for a tapered inner arch. Once JR got my head around the angles and I googled some trigonometry - I started to build this template in FreeCAD.

Looks messy, but you only need to update 4 constraints against the keystone brick (inner and outer length, side length and mortar joint size - all the other bricks are then identical to this, with parallel sides). It will then leave you with a 'gap' above the bottom course of bricks to try and tie in nicely (guess). If the dimensions are too big, then it overlaps...

[fnbroken]

I finished modelling the 1100mm (43") design and converted that into a materials list and estimated the cost of the main, known components. This size does not easily work into standard sizes in Aust if you want to minimise cutting and wastage. So I recut the CAD files, re-estimated materials for a 1000mm (39") WFO and I believe this will be still plenty big enough, less wastage and simpler math and brick cutting to boot. I wont update the original specifications, as I think they are pretty solid if someone wants to do themselves a big WFO. Updated specs below:

1000mm (39") WFO Specifications

• Corner style design
• Igloo pompeii oven @ 1000mm (39") where the dome wall thickness is:
  • 115mm (4.5") - using a standard 75mm firebrick
  • 50mm (2.0") - CalSil blanket
  • 110mm (4.5") - Vermicrete (10:1)
  • 25mm (1.0") - Render
  • 0mm - Waterproofing sealant
  • Total wall width ~ 300mm (12.0")
  • Total dome width ~ 1600mm (63.0")
• Inner arch: 500mm (20.0") by 315mm (12.5") ID (63% of dome radius, round for std brick size) integrated with dome walls on a sailors course to maintain hemispherical top curve
• Outer arch:
  • 700mm (23.5") ID by 350mm (13.5") deep (1.5 bricks) providing a 90mm (3.5") reveal with a serpentine style construction
  • 200/250mm (8.0"/10.0") double wall stainless flu, 900mm (36") high with spark arrestor and rain cap
  • granite landing with ash chute
  • Thermal breaks: 50mm (2.0") stainless on landing as a plug to the ash chute, 10mm (3/8") recessed with ceramic rope on arch + sealant
  • Total oven depth ~ 1700mm (67.0")
• Stand:
  • Foundation: 2100x2100x150mm reinforced concrete (83.0"x83.0"x6.0")
  • Stand: 850mm (33.5") - 4.5 besser block course reinforced with rebar, rendered to match stenciled concrete
  • Hearth:
    • 2000x2000x120mm reinforced concrete with formed ash chute (79.0"x79.0"x4.5") and weep hole(s)
    • Builders plastic
    • 105mm - vermicrete (5:1) (4.0")
    • 50mm - CalSil board (2.0")
    • 75mm - firebrick (herringbone pattern) (3.0")
    • Total hearth height: 350mm (13.5")
    • Bolts concreted in for ash chute box
  • Total working surface height ~ 1200mm (47.0") (just above my elbow height)
• Final surround: polished concrete and/or granite tiles sloping away from oven

Now to plan arch and brick sizes/cuts ...

Thanks for the template JR - been years since I did some angles like that!

[fnbroken]

Thanks Deejayah - will have to do some hunting to get something similar in Aust.... I had it at 50mm (2") but then notice you all wish it was thicker. Will look into a 75mm (3") design.

[deejayoh]

get a big green egg/Kamodo grill gasket to seal the door. Works much better than rope gasket. If your door is deep enough, no need for any stand or bracket. Mine is 2" deep and it never moves