39" Stargate Pompeii

[Amac]

Hi
After hogging Aceves thread and hopefully acquiring some valuable insights from studying the builds of Aceves, Gianni, Sharkey, Karangidude and some others - I have finally got around to start my own thread. This is an excellent forum, but I probably rushed ahead and poured my slab a little bit early. I have built it just behind a retaining wall on my sloping back garden, so there is no wood storage. What is worrying me is the possibilty of rising dampnesss affecting the oven later. But apart from remedial drainage if required I don't propose to make any other changes.
I laid about 4 inches of vermicrete - surrounded by concrete, hopefully mixed to the ratio recommended - but to be honest it was more guesswork than actual measurement.
The plan is to build a brick dome of 39" diameter. "Plan" is probably too formal a word to describe the vague ideas I am working on. I originally intended a 36" and increased it as a kind of compromise between 36" and 42". Looking at the dome opening arches of Gianni, Aceves and Karangi Dude, I felt I would like an entry arch cut in that way, but I have to cut all my bricks using an angle grinder (Makita 230mm with a smooth edge diamond blade) so I wanted to keep all the cuts the same. I decided to base it on a semicircular arch !0.5" diameter. This would be very low but by raisng the dome 1.5 inches along with the arch I coulld get the arch opening to 12 ". This would bush the dome height to 21" and the arch to internal dome height ratio to around 57%. I am hoping to be able to lower the dome ceiling to 20" by shortening the indispensible tool after the arch is complete - thereby getting back to a ratio of >59%. I have been reassured that that will not compromise the ovens efficiency. This has all been discussed at some length in Aceves thread.

The weather here has not been great so apart from cutting a few of the first rows and a (1/2 brick) soldier course I haven't a lot to show, but today was quite good so I managed to cut most of the floor bricks. I also cut the arch bricks - twice since the first attempt was based on a wrong measurement - but I was able to trim them so the opening arch at about 3" is a little narrower than I would have liked. I have uploaded arch photos - the first one shows how to get the correct cut for the brick for a semicircular arch on a hemispherical dome. Note I will not be tapering the arch bricks but the cutting principle is the same. I would maybe also in hindsight have had more than one inch of the arch projecting - maybe 2" just so that the insulating blanket will fit comfortably later? But I'm not cutting a new set of arch bricks.

One item which seems not to be available here is FB board or similar. I have laid some vermiculite board (1") under the floor. If I had realised just how brittle this stuff is I probably would have skipped it. I may yet rip it out if it looks like it will cause problems. Anybody here ever use that stuff under the oven floor?
Amac

[GianniFocaccia]

Looking good, Amac. That's quite the IT you've built! Can't wait to see this oven come together, built with your hands and an angle grinder.
Gianni

[Amac]

]Hi Gianni

That's quite the IT you've built!

I based it on a design of Jcg31 but I don't have a welder (can't weld!) and I had a lot of old floorboard cutoffs, a handsaw, a drill and some long winter eveningsl
Amac

[brickie in oz]

A Stargate oven, cool, every time you put food in it vanishes and pops up in somebody else's oven on the other side of the planet.......

Ill put my order in now for a nice pork belly.

[Amac]

Hi Al
Just let me know your "stargate" destination address and I'll do what I can
To be honest I had no idea what a stargate was (still don't really) until my wife asked me why I was drawing a onee? Two of the "kids" said exactly the same thing and showed me later on the telly and sure enough I had drawn a stargate. As well as that I estimate that at midday on the winter solstice our own star will light up the chamber interior as Newgrange Stone Age Passage Tomb - Boyne Valley, Ireland so what could I do?
Amac

[Lburou]

Originally Posted by Amac

Hi Al
Just let me know your "stargate" destination address and I'll do what I can
To be honest I had no idea what a stargate was (still don't really) until my wife asked me why I was drawing a onee? Two of the "kids" said exactly the same thing and showed me later on the telly and sure enough I had drawn a stargate. As well as that I estimate that at midday on the winter solstice our own star will light up the chamber interior as Newgrange Stone Age Passage Tomb - Boyne Valley, Ireland so what could I do?
Amac

LOL, that is a great story!

I used a rigid insulating board under my oven that has compressed enough to cause cracks in the dome. I recommend you not skimp on the right insulation under the oven.

[Amac]

I used a rigid insulating board under my oven that has compressed enough to cause cracks in the dome. I recommend you not skimp on the right insulation under the oven.

Thanks lburou - I have a bad feeling about that stuff - its already cracked and broken a few places - I have laid the floor on it and was quite happy with how it turned out but still a bit uneasy - I guess its better be safe than sorry. I think the vermicrete layer (about 4") will do. The surface was very rough - I had levelled it under the board with a dry mix of sand coal ash and portland. Will it be OK to lay the floor bricks on the vermicrete if I lay them on the sand/fireclay mix. How thick should that be?

brickie - watch out pork belly on the way see photo 2

[brickie in oz]

Cool, Ill let you know when it gets here.

[Lburou]

Originally Posted by Amac

....snip.... Will it be OK to lay the floor bricks on the vermicrete if I lay them on the sand/fireclay mix. How thick should that be?

brickie - watch out pork belly on the way see photo 2

Yes, as thick as necessary to level the floor, no more.

[Karangi Dude]

Hi Amac,

Looks like you are off to a good start.
Amac, I followed the discussion about your planned arch on Aceves thread and I must say I am not sold on the idea, (please don't think I am putting a negative spin on it) but it will be interesting to see what happens as you go up the courses if you can maintain a nice round shape or if you have to modify the dome bricks to match up with your arch.

Amac, I hope it works out the way you planned so that other members can gain from your experience.
Thanks for sharing, we are always looking for new ideas.