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After writing this I realized I had rambled on a bit. I have put some questions at the end, seperated from my waffle, if that helps 
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On and off for the last 2 weeks I have been constructing my first pizza oven. I did a course with Alan Watt just over 2 weeks ago which gave me the motivation to get started. This also lead me to FB which has made the whole build more interesting to say the least.
So far I have put about $300 dollars into the build using a combo of stuff I had lying around and purchased materials.
I will post photos later but just wanted to start this thread as I had been putting it off.
I used some "common" bricks I had removed from my house during a reno and set about building my base under a reasonably new awning at the rear of my house. I had considered the flue but didn't realize it would finish so close to the ceiling. I will probably have to put a bit more time into this sooner rather than later.
The brick base ended up being just over 1300mm square. I put an 8mm bar across the front plus one across the middle with 2 more courses of bricks on each. I had never laid bricks before so this took a fair while, constantly checking that I was square and level. I think it turned out okay. I used a mix of 5 sand to 1 cement and a splash of Bycol in my water. The sand wasn't brickies sand so it had no clay. I don't know if this will cause the sky to fall, but we will see.
At the course we used a 12mm sheet of fibre cement for the base. I opted for a sandwich of 6mm board plus two layers of 3mm or 4mm making up 12mm to 14mm. I wavered between something like this and a slab. I hope it won't come back and bite me.
On top of this I placed a layer of 12 600x200x50mm Hebel blocks. I wanted something a bit deeper, say 75mm or 100mm but they only had the 50. I feel I may have let down the insulate, insulate, insulate motto here.
Next I loose layed some 230x115x40 clay pavers. I opted for blonde ones as they are apparently higher is something that makes them tolerate a little bit more heat (it may have been aluminium silicate but I only just overheard it at the course). Mine had rounded edges on both flat faces so when I laid them they left little valleys. I had a sort of brain snap and spread some of the homebrew high heat mortar (3:1:1:1 - sand:cement:lime:fireclay) mortar into these valleys and sponged them down pretty well. I hope after firing it will harden right up and avoid crunchy bottoms on my pizza.
I chose to create my dome floating around my floor. I used some of the mortar from above to fill up the big gaps around the edges rather than cut down some pavers (I ended up cutting some of the pavers down later and realized how easy it was with a diamond blade so probably should have filled these big triangular gaps with cut pavers).
I popped cardboard inside my soldier course (are they still soldiers when they stand on their sides rather than their ends?) and underneath it to try and keep it floating. I smooshed a bit of mortar around the outside of these soldiers as I had a bit left, but not much. This was done half heartedly as I knew the dome would hold them in place.
I then went about molding up the sand dome. The sand was wet from an earlier shower which made it really easy to mold. I did fuss over this a little. I got my half avocado/pear shape. I covered this with newspaper that I dipped in a bit of clayey water that was sitting in a bucket from an earlier process.
After much research, reading, coffees, head scratching and beer I ended up going with a 3:2:1:1 - sand:fireclay:cement:lime mix for my dome. This was a bit of a combo of the high heat mortar from FB, the mix used at the workshop I did and some ebook clay oven recipe. I figured more clay is better and lime will stand up to the heat better. I think I read on the "brickless on a shoestring" thread here that using the high heat mortar for the dome is uncharted territory. And as I didn't use a "reo" structure I was in even deeper (or at least different) water so why not change the recipe and see what happens.
When I mixed the stuff up I made sure the kids weren't in breathing distance (not so much care for myself). But I did let them help me put it on the sand mould. I stopped this when the lime got into a cut on my hand and turned the skin black. Those little burns are still stinging like a "you know what." Luckily the kids missed out on any chemical burns. I will wear gloves next time and the kids will need to have the full complement (gloves, eyes and mask) if they want to help with lime and or cement work.
I put this on as little squished pancakes, about an inch thick (probably more like 30mm), overlapping each other. I think this layer may have ended up being 30mm to 40mm. Part of the way through a crack formed but I feel this was just the weight of material causing a separation. Needless to say I patched it up.
I'm thinking I will need to put another, slightly thinner layer on to take my dome thickness up to around 40mm to 50mm. From what I can work out if my floor is 40mm thick then my floor needs to be somewhere between 40mm and 80mm or some such. I believe there needs to be balance between the thermal layers.
I finished up this layer around 5pm and around 2am remembered that I forgot to put my flue in. Luckily the dome wasn't too hard, more crumbly. I got a serrated knife out and started scratching out the circle for my flue. Got it in with a pretty snug fit. Regardless if I go for another layer of thermal mass I will need to give this a much better housing.
Just now I pulled the door mold out and started removing sand. The dome didn't collapse so that is a good thing.
I did a quick measure and found my door ratio fell in a big hole.
flue output inside the dome: 290mm
door height: 230mm
door width: 520mm
dome height: 520mm
So flue output to dome height is 55%;
door height to dome height is 44%; and
door height to flue output height is 80%.
The magic ~63% is GONE! I cut my door mould to 300mm being just about right. However I think the door moving let the sand settle and dropped the roof level somewhat. There is a lot of thickness at the door opening, probably 50mm or so.
I still plan on putting a 100mm or so vermicultie/perlite or sawdust insulatng layer on top of this. Plus I want to start curing the dome. I don't know if I want to start small fires before or after I put the insulating layer on and need to go and do some more research (after posting this).
************************************************** ***
If anybody is still there after my novel of a post I have a few questions:
* For a floor thermal thickness of 40mm is the dome thickness of 30mm to 40mm enough or should I thicken it up a bit more? Maybe take it up to 50mm to 60mm?
* Should I grind the door opening back up as high as possible? I could probably get up to around the flue output of 290mm.
************************************************** *******
On and off for the last 2 weeks I have been constructing my first pizza oven. I did a course with Alan Watt just over 2 weeks ago which gave me the motivation to get started. This also lead me to FB which has made the whole build more interesting to say the least.
So far I have put about $300 dollars into the build using a combo of stuff I had lying around and purchased materials.
I will post photos later but just wanted to start this thread as I had been putting it off.
I used some "common" bricks I had removed from my house during a reno and set about building my base under a reasonably new awning at the rear of my house. I had considered the flue but didn't realize it would finish so close to the ceiling. I will probably have to put a bit more time into this sooner rather than later.
The brick base ended up being just over 1300mm square. I put an 8mm bar across the front plus one across the middle with 2 more courses of bricks on each. I had never laid bricks before so this took a fair while, constantly checking that I was square and level. I think it turned out okay. I used a mix of 5 sand to 1 cement and a splash of Bycol in my water. The sand wasn't brickies sand so it had no clay. I don't know if this will cause the sky to fall, but we will see.
At the course we used a 12mm sheet of fibre cement for the base. I opted for a sandwich of 6mm board plus two layers of 3mm or 4mm making up 12mm to 14mm. I wavered between something like this and a slab. I hope it won't come back and bite me.
On top of this I placed a layer of 12 600x200x50mm Hebel blocks. I wanted something a bit deeper, say 75mm or 100mm but they only had the 50. I feel I may have let down the insulate, insulate, insulate motto here.
Next I loose layed some 230x115x40 clay pavers. I opted for blonde ones as they are apparently higher is something that makes them tolerate a little bit more heat (it may have been aluminium silicate but I only just overheard it at the course). Mine had rounded edges on both flat faces so when I laid them they left little valleys. I had a sort of brain snap and spread some of the homebrew high heat mortar (3:1:1:1 - sand:cement:lime:fireclay) mortar into these valleys and sponged them down pretty well. I hope after firing it will harden right up and avoid crunchy bottoms on my pizza.
I chose to create my dome floating around my floor. I used some of the mortar from above to fill up the big gaps around the edges rather than cut down some pavers (I ended up cutting some of the pavers down later and realized how easy it was with a diamond blade so probably should have filled these big triangular gaps with cut pavers).
I popped cardboard inside my soldier course (are they still soldiers when they stand on their sides rather than their ends?) and underneath it to try and keep it floating. I smooshed a bit of mortar around the outside of these soldiers as I had a bit left, but not much. This was done half heartedly as I knew the dome would hold them in place.
I then went about molding up the sand dome. The sand was wet from an earlier shower which made it really easy to mold. I did fuss over this a little. I got my half avocado/pear shape. I covered this with newspaper that I dipped in a bit of clayey water that was sitting in a bucket from an earlier process.
After much research, reading, coffees, head scratching and beer I ended up going with a 3:2:1:1 - sand:fireclay:cement:lime mix for my dome. This was a bit of a combo of the high heat mortar from FB, the mix used at the workshop I did and some ebook clay oven recipe. I figured more clay is better and lime will stand up to the heat better. I think I read on the "brickless on a shoestring" thread here that using the high heat mortar for the dome is uncharted territory. And as I didn't use a "reo" structure I was in even deeper (or at least different) water so why not change the recipe and see what happens.
When I mixed the stuff up I made sure the kids weren't in breathing distance (not so much care for myself). But I did let them help me put it on the sand mould. I stopped this when the lime got into a cut on my hand and turned the skin black. Those little burns are still stinging like a "you know what." Luckily the kids missed out on any chemical burns. I will wear gloves next time and the kids will need to have the full complement (gloves, eyes and mask) if they want to help with lime and or cement work.
I put this on as little squished pancakes, about an inch thick (probably more like 30mm), overlapping each other. I think this layer may have ended up being 30mm to 40mm. Part of the way through a crack formed but I feel this was just the weight of material causing a separation. Needless to say I patched it up.
I'm thinking I will need to put another, slightly thinner layer on to take my dome thickness up to around 40mm to 50mm. From what I can work out if my floor is 40mm thick then my floor needs to be somewhere between 40mm and 80mm or some such. I believe there needs to be balance between the thermal layers.
I finished up this layer around 5pm and around 2am remembered that I forgot to put my flue in. Luckily the dome wasn't too hard, more crumbly. I got a serrated knife out and started scratching out the circle for my flue. Got it in with a pretty snug fit. Regardless if I go for another layer of thermal mass I will need to give this a much better housing.
Just now I pulled the door mold out and started removing sand. The dome didn't collapse so that is a good thing.
I did a quick measure and found my door ratio fell in a big hole.
flue output inside the dome: 290mm
door height: 230mm
door width: 520mm
dome height: 520mm
So flue output to dome height is 55%;
door height to dome height is 44%; and
door height to flue output height is 80%.
The magic ~63% is GONE! I cut my door mould to 300mm being just about right. However I think the door moving let the sand settle and dropped the roof level somewhat. There is a lot of thickness at the door opening, probably 50mm or so.
I still plan on putting a 100mm or so vermicultie/perlite or sawdust insulatng layer on top of this. Plus I want to start curing the dome. I don't know if I want to start small fires before or after I put the insulating layer on and need to go and do some more research (after posting this).
************************************************** ***
If anybody is still there after my novel of a post I have a few questions:
* For a floor thermal thickness of 40mm is the dome thickness of 30mm to 40mm enough or should I thicken it up a bit more? Maybe take it up to 50mm to 60mm?
* Should I grind the door opening back up as high as possible? I could probably get up to around the flue output of 290mm.
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