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  #11  
Old 09-20-2011, 04:57 AM
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Join Date: Jan 2011
Location: japan
Posts: 17
Default Re: Economy 24" cast in place in Japan

Thanks for the advice, David. I really couldn't locate the fireclay to make this a really cheap build. In the end, I decided the casting cement made by Asahi seemed to be an easy route to follow. However, the price has gone up drastically in the past year or so, but it still fit into the budget for a cheap bill, so I plopped down some money for the casting cement, 4,500 yen per 25kg bag. My original calculations were for 3 bags. I did a rough figure of the inner and outer sizes of the domes as half spheres and respective volumes, and a desired thickness of 5 centimeters gave me a certain amount of liters. The manufacturer's site gave a rough shot of liters of mixed material per bag and so I ordered three. But the nice upshot of it was..... in the end I used two and the third is now in storage for a planned, even lighter, portable one done the same way, but with insulation bats instead of vermiculite on top. But that is a tale for down the road.

I was lucky to have a buddy come out the day I picked to mix up the casting. Asahi makes two types, one that is "packed" on, worked by hand into a lathe or similar, and a second type which is for troweling. I went this way and that, use mesh or not. I checked with the masonry store, and the owner confirmed what I hoped, that a small dome like this one would be okay without lathe or mesh, so I went with the trowel type.

Of course, that didn't mean we started with a trowel. IThe hard part would be keeping the depth consistent. We opted to maybe kill two birds with one stone. We would set the final thickness on the base to about 10 cm high, and hope that would give a good foundation for going higher in thinner coats since it seemed so vertical, and a determined thickness would give our eyes a reference as we went up.

We ended up do a combo of packing the cement on by hand and then troweling it out. Packing by hand allowed us to do a slight vibrating action which I think let a new layer blend in well with the previous. We worked quickly, almost too quickly because we often needed to wait to let the mud set up some so the next layering wouldn't make it set from gravity.

Still thinking that some sort of "aggregate" would be beneficial and stainless needles not handy, I lugged out a box of old screws and we pasted those in all over the place in the under layers. Not sure if we were just playing or if this might help, who knows.

The next day the sand form was dug out. The instructions said the casting was good to go in 6-8 hours. And it was. The wood forms came out perfectly from inside and our vibrating trick seemed to give a nice smooth interior finish as well. No cracks and sounds sturdy.

Day after I built the curing fire. Again the instructions were simple and easy. One fire with slowly rising temperatures, a rest at 200c and 300c, altogether 5-6 hours, and finished. Very easy and no problems.
Attached Thumbnails
Economy 24" cast in place in Japan-casting-1.jpg   Economy 24" cast in place in Japan-casting-2.jpg   Economy 24" cast in place in Japan-casting-3.jpg   Economy 24" cast in place in Japan-casting-4.jpg  
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  #12  
Old 09-20-2011, 05:08 AM
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Join Date: Jan 2011
Location: japan
Posts: 17
Default Re: Economy 24" cast in place in Japan

With the casting cured and looking good, it was time for the vermiculite. I really enjoyed this part. It's fun to mix and fun to slowly watch the shape take place.

I mixed it at about 8 to 1. I found it easiest to throw the V into the mixing bed (a huge plastic box), dampen it slightly with a garden watering can while mixing it up with my free hand. Then, sprinkling in the cement while doing the same motion. After adding all the cement, a good mix by both hands, then again sprinkling little by little with the can until the mix is just wet enough to hold together and set the cement off. I probably used about 90 liters of V.

I followed the same pattern as the casting, setting a base row and working from that. But I approached the top, the curve looked like it might through my thickness off visually, so I put a row of insulation on the top to give me something to work toward and keep the thickness the same over the curve. Hence the photo which looks like a mohawk!

Up to this point, I have spent about 30,000 yen (360 US maybe?). The only items which I didn't pay for were the scaffolding pipes and the durock board as the base. I think I have managed to make this a real economy build and I hope others give this a shot.
Attached Thumbnails
Economy 24" cast in place in Japan-insulating-1.jpg   Economy 24" cast in place in Japan-insulating-2.jpg   Economy 24" cast in place in Japan-insulating-3.jpg  
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  #13  
Old 09-20-2011, 05:13 AM
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Join Date: Jan 2011
Location: japan
Posts: 17
Default Re: Economy 24" cast in place in Japan

After a week of air drying, I fired up the stove to dry out the insulation layer. I got a beautiful fire going, and it cleared the inside of the dome wonderfully. The vermiculite steamed away. And of course I got some good cracks in the V, but I think that is to be expected. I will follow David's advice (on another thread elsewhere) to have a number of firings before doing a render. So hopefully I'll have the final photos sometime later this fall.

Thanks to everyone on FB. Great place to learn and I hope my little experiment gets others thinking too.
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  #14  
Old 09-22-2011, 02:40 AM
Laborer
 
Join Date: Sep 2009
Location: brisbane
Posts: 89
Default Re: Economy 24" cast in place in Japan

Top oven, been thinking of going that way but a little bigger and casting in place but with thin ply to seperate the pieces to make it a 4 cast piece oven.
I will keep watching.
Rob
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  #15  
Old 09-26-2011, 07:43 PM
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Join Date: Aug 2011
Location: Manila, Philippines
Posts: 13
Default Re: Economy 24" cast in place in Japan

I am planning to brush a solution of starch on the newspaper and let it dry to provide the moisture barrier for the castable. Am thinking it would be easier to burn off as well later...
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  #16  
Old 02-15-2012, 04:55 AM
Serf
 
Join Date: Jan 2011
Location: japan
Posts: 17
Default Re: Economy 24" cast in place in Japan

Finally got some final photos of the build. Oven works great. In the photos you"ll notice there isn't a chimney. Actually, I built it as removable since we have a lot of rain in Japan. Although it is under snow, I also built a removable yet water tight (so far) lid on the roof to let me poke the chimney through when firing. I also made a damper for the flue to help hold the heat in when I'm in the cooking stage.
The door has two small "adjustable" dampers as well. Soup can lids!
This was such an easy build, thanks to the store of knowledge on this forum.
Attached Thumbnails
Economy 24" cast in place in Japan-pizza-oven-22.jpg   Economy 24" cast in place in Japan-pizza-oven-24.jpg  
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  #17  
Old 02-15-2012, 04:02 PM
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Join Date: Aug 2011
Location: Manila, Philippines
Posts: 13
Default Re: Economy 24" cast in place in Japan

Here are pictures of my economy 24 in Quezon City, Philippines. Good size for single 12" pizzas!
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Economy 24" cast in place in Japan-qc-oven1.jpg   Economy 24" cast in place in Japan-qc_oven.jpg  
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