UK 34" rounded square Oven Progress.

[hulkiebear]

As this project is starting to consume my life at the moment, and is the main thing on my mind, I thought I would blog it here, as you guys, unlike my Wife/Family/Freinds are actually bothered about what I am doing, rather than making comments like, "uh huh, thats nice dear!"

I have got pretty much all my ideas from this forum, so hope I can give a little back to future builders.

So, My base is built 150cm x 150cm, IT has turned out to be a bit higher than I wanted, but thats better than too low, as I can build some decking infront to even it out.

I used 6" concrete blocks in a kinda cross between a H and an A, the reason for this is, I did not want huge re bars and a massively thick concrete slab on the top, it is just 5" thick, with reinforcing mesh inside. I did use 2, 4"x3" lintels across the front(hidden behind the brick arch) also some lintles in the back section, this gives me two large storage areas underneath, the centre wall acting as support.

[cynon767]

Re: UK 34" rounded square Oven Progress.

I really like those brick arches worked into the stand like that.

[hulkiebear]

Re: UK 34" rounded square Oven Progress.

When I orignally decided on building a Pizza Oven, I had my mind set on a Barrel oven, ue to the easy of building and the apperance it would give, I never liked the look of the dome shape. As I researched pizza ovens, it became clear that the dome shape was much more suited to my needs. But I was still worried about the quality of the finish of the inside(firebricks) of the oven, I know that very few people will look, but I would always know!

So, after seeing the tool that pivots in the centre to hold the bricks while they set, I decided that I could achieve a spot on dome oven that would look great! Then after another thread in the Newbies forum, Rasty's mentioned the idea of a rounded cornered square oven, the idea set itself in my mind, and now I have set myself on a design that comes from that!

To cut the long story short, I took the design of an 26" round dome, split it into it's quarters, expanded it out, and inserted 8" inbetween the quarters, thus giving a 34" rounded corner dome! If that is a little confussing, hopefully a few diagrams will help, or photos as it's built might!

Here are a couple of diagrams and photos of dry runs on setting the oven out! also, A nice stack of new Fire bricks! And my Slammed VW T5 with the pallet that just fitted, with minus 4 mill to spare!(some excellent forklift driving by the lads at the depot!)

[cynon767]

Re: UK 34" rounded square Oven Progress.

It looks pretty cool... the one thing I would worry about is the stability of the arch in that center section where it goes more or less horizontal.

[hulkiebear]

Re: UK 34" rounded square Oven Progress.

Thanks cynon, I was well please with how they turned out! They are reclaimed clay bricks, which I don't think are that strong!(hence the concrete lintels behind them).

I made a form for the front arch, then after finishing the front arch, I simply trimmed the sides of to fit into the smaller side enterance! quicker and easier!
My only worry is that they do not stick out enough(20mm from blocks), I still need to render the blocks, so will try to keep the render quite thin!

Yes, good point on the flat arch point! I still need to ensure that I can solve this problem before I am confident this design will work, at the moment I am thinking of shaping the bricks to have teeth that fit together in all four directions!

It is true to say that I am kinda making it up as I go along!

[cynon767]

Re: UK 34" rounded square Oven Progress.

sorry... accidentally deleted my earlier post...

what I had looked at before here (scroll down to see picture #2) was different. I'm not sure which way would be easier to build or more effective. Just thought I'd throw that out there as another solution to the same problem.

[hulkiebear]

Re: UK 34" rounded square Oven Progress.

Thanks for the link, interesting stuff, it makes me think, the area in the centre of the dome(that was cut off) forms a ring that supports the outer dome, with out actully existing! Example, St Pauls cathedral in London, if you have ever stood inside under the dome, it seems that there is not alot holding up such a large structure. So, with the lower part of the dome and archs that push in, will hopefully clamp the key stone bricks.

a quick diagram to show what I mean by shaping the key stone bricks at the top.

[cynon767]

Re: UK 34" rounded square Oven Progress.

I guess my concern would be with what's holding up the bricks that hold up the keystone. With a continuous arch, the downward thrust of gravity is taken up by transferring the stress horizontally outward to the next brick; but with the completely flat section in the middle, I would worry about the center falling out with only mortar holding things in place.

That's why the I envisioned the cut-off sides of the dome- that way you get a little more floorspace and a little more height without risking the top of the dome collapsing or having problems with the barrel-vault side stability.

[hulkiebear]

Re: UK 34" rounded square Oven Progress.

Progress report, things have been a little slow on the buildig front over the last couple of weeks, I am training for an Iron Man at the end of June, so need to concentrate on that quite alot. Anyway, had a good couple of days, I built the arch accross the centre and to the rear and cut the blocks for the bottom course.

My main concern was the arch not holding up, but after building the arch upto the key stone then the next day putting the 3 centre bricks in, it held up just fine. then after building the rear arch and that held too, I am feeling much more confident and euthisiatic about the project.

Due to the morter(or screed) having larger particules in it(about 4-5 mill at times), I was unable to create neat morter joints, so opted for joints with no morter and bricks jointed directly to each other, this does mean, all my cut bricks will need to be spot on, but this just means taking a little bit longer. I fill the rear of the joints with the screed, but I am trying to leave 20-30 mill so once it is built, I can point the whole outer oven to make it air tight.

here are a few pic's, should get another day in this weekend to hopefully build the enterance.

[brickie in oz]

Re: UK 34" rounded square Oven Progress.

Never seen an arch done like that before?

Once it heats up and expands the top will drop out, maybe not the key brick, but those holding it in will......then the key brick.....

[dmun]

Re: UK 34" rounded square Oven Progress.

I'm watching this come together with interest. You have designed the anti-catenary arch and have at least six running seams from the top of the dome to the bottom. I think the success of the whole enterprise depends upon how you build your entry arch, and tie it into the dome, as it will bear a greater than usual proportion of the weight of the dome.

So, let's see... Strange geometry, unknown mortar... I really wish you the best, but i'm sceptical at this point.

[hulkiebear]

Re: UK 34" rounded square Oven Progress.

It does appear that I do enjoy a challenge!

I am still thinking about the stability of the arch, for now, it seems very strong, but that could change, but Idon't think by much. I think that the weak spot will be the middle of the arch on either side, it is impossible for the key stone to fall, unless the arches either side fail some how. So, I am toying with the idea of a rebar and concrete belt over the top about 3" by 3", or maybe a pillar behind each side, but for now, the thing is solid enough.

Today, hopefully the enterance will get designed!

[dmun]

Re: UK 34" rounded square Oven Progress.

but for now, the thing is solid enough.

I'm glad to hear this. The bracing ring you should be thinking about is around the bottom, not around the top. All the forces trying to bring down your dome have to work outward, before there's any downward movement. I would urge you to consider a "C" shaped ring around your dome, tied to your support slab. Did you look at the page I linked? Look at the illustration under example one of "STABILITY PRINCIPLE". It almost exactly describes your dome shape, and if I were you, I'd try to buttress those outward forces.

Remember that a dome that heats and cools is changing shape and size with every cycle. It's not a fixed shape, it's a dynamic system.

[hulkiebear]

Re: UK 34" rounded square Oven Progress.

Thankyou dmun, for all your input! I really appricciate it!

I checked out the link, interesting stuff! I think I mentioned in a previous thread about a concrete sleeper at either end of the arch, the suggestion of bracing at the bottom of the arch in a C shape was kinda what I meant. but I was just going to brace the centre arch at either end, also the rear arch. The reason that I was only going to do it at the bottom of the centre arch was that I figured, if that is solid, the 4 quarters will just lean in on them, also, I was a bit concerned about heat bleeding out through the support, if only a little!

I have added a couple of blue blobs on a picture to help show what I mean.

The bracing at either end, will have a couple of spreader bolts down into the slab, to act as ties.

what do you think?

[hulkiebear]

Re: UK 34" rounded square Oven Progress.

A few photos of the progress over the weekend.

Centre and rear arch up, very strong!!!
started to fill in the quarters(phew lots of cutting an fine tuning cutting!)
The enterance is taking shape and I know where I am going with it, and feel confident it will work.

A couple of issue's I am thinking about are, The size of the flue(maybe 8" diameter) and the insulation over the dome, originally I was going to form a house around it and just pour in vermiculite, but I (and importantly the missus) are really starting to enjoy and appriciate the dome shape and want it on veiw, so now, can I just use vermiculite cement(like with the base and a render over the top to water proof it? I really don't want to use blanket insulation or make it to large?

Thoughts?

cheers
Lee.