Structural Slab for new WFO

[UtahBeehiver]

Re: Structural Slab for new WFO

Yes I am a native Utahn but travel a fair amount. A long way from the Great Lake region. Can't recall where anyone has actually had to remove a hearth brick so I think you have the right idea of placing dome on brick. Good luck.

[mikku]

Re: Structural Slab for new WFO

Russell, here are a few more pics.





I laid the hearth bricks out on a table, first for marking for cuts.

Then looked at the scale of this oven.. it is only 29 1/2" diameter (750mm).

I don't think I can reach inside to change bricks if damaged!

My wife would not have the upper body strength to do it either in such a cramped position either!

So, I am going to pick up an additional 6 brick, fill in the perimeter with some 1/2 cuts and place the dome on top!

If there is a problem in the future--options:

-live with it
-cut some tiles to fit on top of hearth
-tear down and rebuild

Any are not that big a deal!

Now I am thinking of some type of light weight enclosure-but plans change (daily!!)

These brick are laid directly on top of the pericrete layer without anything below, used a level to check straightness; swapped out one center brick and no rocking or spaces beneath the level --all directions! Think I'm going to leave it alone before making it worse!

[mikku]

Re: Structural Slab for new WFO

I thought you are located in Utah?

My country is: North Country wilderness, near "Boundary waters Canoe Area, Superior National Forest- Minnesota, USA!

Also a beautiful place!! Wonderful lakes, rivers, pines, good fishing, lots of white tailed deer!

I live in Japan for a lot of reasons, but still a Yank from Scandanavian stock.

Thanks for compliments.

Yes, there are a lot of friendly people here. No fear taking a walk anywhere at night!

Lots of heritage, nearby snow topped mountains, good water from mountain springs, tall trees, few people - at least in this area!

But little wildlife AND cannot eat the mushrooms for a while! --(maybe another 30 years). You know the "Cesium story"!

[UtahBeehiver]

Re: Structural Slab for new WFO

Mikku,

I am very impressed with the quality work of your casting. I had a chance to visit your country earlier this year and found your country very inviting, friendly people, and would not hestitate to revisit. Keep sending pictures of your progress. Will be watching with interest.

[mikku]

Re: Structural Slab for new WFO

The insulative layer seems to have set up hard and flat.
The last batch I mixed, there was about a scoop full left over- so I put it into a plastic bag to retain moisture (as a sample).

That also set hard, but it will crack if you apply a significant amount of hand pressure and if you persist in working it-- you can make it crumble.

I don't think it will pose a problem - the structural slab (is) a permanent form.

Just wondering if that is the nature of the beast? Or a problem with the amount of water in the original mix?

The insulation layer has been covered with plastic for many days now and still there is moisture on the underside of the plastic facing the insulation.

[mikku]

Re: Structural Slab for new WFO

Last casting photos:









There is a definite difference in the finish of the casting between inside and outside, all molds were cast filling from the top. The air/water migrated upward when vibrated--leaving the somewhat course texture on the outside. The inside finish is glass smooth (or as smooth as the mold).

[mikku]

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!

[mikku]

Re: Structural Slab for new WFO

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











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!

[brickie in oz]

Re: Structural Slab for new WFO

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......

[mikku]

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!

[mikku]

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!

[david s]

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.

[mikku]

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.














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!

[mikku]

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.






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!

[mikku]

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