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  #11  
Old 02-01-2013, 11:21 AM
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Default Re: Structural Slab for new WFO

Quote:
Originally Posted by mikku View Post

allowing for the hearth brick to be installed (flush) with top as a complete product.
All your heat will leak out sideways through the concrete if the hearth bricks touch the concrete.
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  #12  
Old 02-01-2013, 01:28 PM
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Default Re: Structural Slab for new WFO

I am sorry I do not describe things more accurately.
What I was referring to was the relationship of the height of the materials.
If you look at the oven base as viewed from above:

-oven inside diameter 750mm
with wall thickness of 80mm
-dome outside diameter 910mm
-size of block out in structural base 1110mm
This allows for the perimeter of the dome to have a 100mm ring of insulation.

The new scenerio that I described for the brick floor-

-brick cut to inside dimension (750 minus ??5mm)
cast refractory ring (inside dimension 750mm), ring width (same as firebrick width 114mm); outside dimension (978mm)
-size of block out remains same at 1110mm
Allowance for perimeter insulation to refractory 66mm (still better than 2 1/2")

So that should be OK, if I did not miss something else.

Reasoning for casting refractory ring around firebrick:
-Should tend to hold bricks in position better than a second ring of brick.
-$$$, I have an extra bag of ACG castable ($31)non-returnable vs the cost of the extra firebrick ($78) (which I don't have); just watching the pennies!

Thanks for checking out the details of this build, your thoughts are really appreciated!

mikku
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  #13  
Old 02-02-2013, 03:51 AM
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Location: Tochigi Prefecture, Japan
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Default Re: Structural Slab for new WFO

Today I became a "mobile structural slab!".
Searched a few of the home centers for short steel stock but came back empty handed. There is a fabricator of steel buildings not too far away so I stopped there and asked the "Shacho" -"boss man in Japanese" if he had any 90x90x6mm off cuts? He said not that size but said to look in the "trash box", there should be some larger-100x100x6 stock.

No luck there--then he pointed to where they were sheering angle for one of their projects. Wa La! There was a stack of pieces about 500mm long! I picked out 4, asked the price...he said "dozo". Just take them!

Went home, layed out holes--drilled and assembled casters to angle! Spent the rest of the afternoon jockeying my "heavy mass"-- (the structural base)! Usually when referring to my "heavy mass" it is "ME!" ha ha

this sucker is really going to be heavy when the firebrick and dome get added.
Now it is about the same as pushing a VW bug around!

Couple of photos for progress--next week firebrick cutting, bricks should show up on Monday sometime.


Structural Slab for new WFO-img_2542a.jpg

Structural Slab for new WFO-img_2544a.jpg

Now, if I get busy with something else, I can roll the assembly in the corner and wait for some slack time again to pick up this project! Moving this mass outdoors is a "forklift project" for sure!

Last edited by mikku; 02-02-2013 at 04:01 AM.
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  #14  
Old 02-02-2013, 05:03 AM
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Default Re: Structural Slab for new WFO

Now that I can get these photos to load, I'll show the preparation work to cast the dome sections.




Structural Slab for new WFO-img_2449a.jpg

Structural Slab for new WFO-img_2450a.jpg

Structural Slab for new WFO-img_2456a.jpg

Structural Slab for new WFO-img_2460a.jpg

Structural Slab for new WFO-img_2467a.jpg

Description:
1) dome half- with formed oven opening.
2) rear dome half
3) inner form for transition
4) transition to chimney support view
5) 3 pcs after castable poured.

All the formwork takes time, but a cutting challenge for trapezium dome (much easier with wood than tackling the same in brick)... At least in my opinion. Actual casting-mixing etc only took a couple of hours. A real fun project so far!
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  #15  
Old 02-02-2013, 12:35 PM
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Default Re: Structural Slab for new WFO

Wow, that's really nice work. And very well thought out. Are you hoping to make more castings using the moulds? I found that wooden moulds do not last too well no matter how well you seal them and moved to fiberglass which holds up much better.
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  #16  
Old 02-02-2013, 02:02 PM
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Default Re: Structural Slab for new WFO

Thank you! Compliments are always appreciated!
This entire exercise is to see what is possible, sturdy forms can be modified easier than starting from scratch again. So if this one doesn't work out, I can try again.
My wife makes great pizza now and is equally talented in bread making and regular baking. I have high hopes for the completed oven. The neighbors are waiting as well-- She bakes as a hobby so the kids and adults around here get a lot of her bakery product. They in return drop things off, fruit, veggies, eggs, fresh fish, etc ... You know when someone you haven't talked to in a while stops by with a gift of fresh fruit--that it is time for her to start baking again!
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  #17  
Old 02-02-2013, 10:54 PM
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Default Re: Structural Slab for new WFO

As far as reusability goes, if my completed oven created some demand for my work, I could possibly get 5 or more castings from these molds. The basic shapes after that could be the starting point for making a proper more permanent mold from fiberglas or steel.

If you have made molds from fiberglas, then I am assuming you are getting a decent amount of work that justifies the expense.

Right now, I am assuming that there is no demand--even within the expat community, those who would have interest in WFO's are long term residents who would probably do their own builds just for the pleasure of a DIY completion.

Regular Japanese families do not have ovens in their homes, except for a toaster type or a convection microwave. If they choose to make bread, there are many electric bread machines around.

Our home has a full size gas oven/range 30" that I had to purchase through a dealer in Japan. The same product is available in USA for a fraction of the price but the special electric parts for 50Hz cannot be purchased outside of Japan--dealership issue!

Did someone say ? "You have to shake the tree to see what kind nuts fall from it".. If nobody wants to claim the quote--I will! So far, no potential customer nuts--but a lot of people interested in the diverse things I do.

A lot of people think I am the only nut!
Making a multi-ton, concrete monstrosity inside a garage! For making an occasional pizza! Maybe I am--but internationally, I think I am in good company!
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  #18  
Old 02-02-2013, 11:01 PM
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Default Re: Structural Slab for new WFO

Quote:
Originally Posted by mikku View Post
The same product is available in USA for a fraction of the price but the special electric parts for 50Hz cannot be purchased outside of Japan--dealership issue!
The Hz difference shouldnt make a difference in a heating coil, the trouble starts with motors, but that too can be got around.

Motors turn slower/quicker with changing Hz, heating coils are hardly effected.

Some years ago I bought a spiderweb gun that makes webs from heat gun glue, there is a heating element and an air blower attachment, the heating element was made for the US at 110v 60Hz, we use 220v at 50Hz.
I adjusted the US plug prongs with pliers and plugged it in, all worked just fine.

Dont try this at home unless you are a trained idiot......
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Last edited by brickie in oz; 02-02-2013 at 11:06 PM.
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  #19  
Old 02-02-2013, 11:25 PM
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Default Re: Structural Slab for new WFO

I searched through casting photos, these give a pretty clear idea of the cast parts:

Structural Slab for new WFO-img_2468a.jpg

Structural Slab for new WFO-img_2470a.jpg

Structural Slab for new WFO-img_2481a.jpg

Structural Slab for new WFO-img_2482a.jpg

Structural Slab for new WFO-img_2484a.jpg

Description:
-first transition casting
-another view of transition
-front 1/2 dome section, showing oven entrance
-another view
-inside landing --transition to chimney.

These are in response to : We need pictures!
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  #20  
Old 02-02-2013, 11:53 PM
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Default Re: Structural Slab for new WFO

120v/60hz vs 100v/50hz!

Crazy power grid in Japan! From Mt. Fuji to the east is 50HZ/to the west is 60HZ!

Most things USA made or manufactured elsewhere- power tools etc work just fine either place! Saws just run faster in USA. I purchase circulating pumps for use in hot water heated floor applications from there just because of cost savings! Huge like 1/10th initially, approx 1/4th after clearing customs etc! Have to look at pumping capacity, head, etc but otherwise just fine!

Trouble with LP gas range- slight difference in gas and amount of methane, this can be solved by re-jetting and air shutter adjustment.

Other problem is electronics for clock- digital OK, analog different story runs off current cycle. Or vice versa but clocks run slower/ same with oven timer. It is something you can deal with but for a proper fix, need the right part and only through authorized dealer here!

Lastly, issue with solenoid in gas valve. 100V not enough to energize valve to open properly. A fix for that is a booster transformer.. or the right part again!

Crazy short story: When I came here the first time a while back, I brought our range from USA along with household stuff, finally got the gas man to hook it up and the cook top worked fine. My wife wanted to try some baking while I was gone at work... That evening, she complained that it was taking a long time to make cookies (a real long time!!!!). When I finally got a day off, I checked things out when she did her next batch. The gas valve never did open the previous time she did cookies. The only thing that heated the oven was the pilot light. I think that the starting sequence allowed enough gas to flow to start the pilot--but there is something in the circuit that measures voltage or resistance or something through the flame and it was not enough to open the main gas valve! We were really happy to find a booster transformer to make the stove work...and so were the neighbors !! fresh cookies, cakes, pies, bread etc etc!
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