Starting my build

[almondsurf]

Re: Starting my build

SableSprings, you have been a great help in my building process. Thank you very much. I didn't think about the sand grooves, but now I will do that. I guess that groved trowel will come in handy again.

The insulation slab looks great! Remember that the only reason for a mortar outer ring is to protect the perlcrete from impact/abrasion on the edges of that insulation slab. So, as long as you are just casting on top (no dancing or mountain climbing practice) you'll probably be fine without the extra mortar ring.
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Also, I guess I will be putting away my skirt and kilt purse, and will let my wife know that there will be no Irish Jig ontop of the oven this weekend because I won't be putting on an extra mortar layer.

[almondsurf]

Re: Starting my build

Another question to all...
In my recipe, I am planning to use 10 50lb bags (1-50lb bag of cement; 6-50lb bags of sand; 2-50lb bags of type S lime; and 1-50lb bag of fire clay)

That's 10 50lb bags total. Do you think this will be enough for the whole 32" cast? I assume it would... but we all know what assuming does.

[david s]

Re: Starting my build

The density of your set, dry castable will be around 1.8 kg/litre (sorry we're metric) If you know the density and the volume, you can calculate the weight of the materials required.

Density =Mass/Volume
Volume of sphere =4/3 pi x r3

A rough guess says you should have plenty for a 32" oven.

[almondsurf]

Re: Starting my build

David... Thank you for taking the time to give the formulas. It would have taken me forever to guess my density. Thanks!

[almondsurf]

Re: Starting my build

I have started purchasing materials for the oven... Yay!
I purchased the fire brick for the floor. Purchased 35 full bricks, but should only need around 20 for the oven and 5 for flue gallery based on the spreadsheet found here. Will return what I don't need.
So far, I have purchased: one 50lb bag of fire clay and some poly rope.
I ordered the melt extract needles (only 2% worth, or 10lbs, based on a 500lb mixed batch) and the ceramic fiber blanket (25sq feet).
I hope to be cutting out the brick floor next week and building the sand mold the week after, possibly applying the cast mix in 2 weeks. I can't wait.

Does anyone know of a good place to order a flue and cap?
(I was wondering if I even need a flue or if I should just make a mold from some 6" tube and build up the castable cement up around the tube 3 feet or so. Then just put a flue cap on top of that. That may look sloppy though?)

[mrchipster]

Re: Starting my build

Are you planning any kind of break between the dome and the outer arch(flue arch)? If not I would recommend it because of heat loss and the ability to easily incorporate a reveal on the dome for your insulated door.

Here in Minnesota stainless flue is readily available used on Craigslist but I see it is not the same in SLC. I am not sure where you are in Utah. So I only looked in SLC.

We can buy class A flue at HD, Lowes, or Menards. Not sure where you would purchase locally.

[almondsurf]

Re: Starting my build

Thank you Chip. I didn't know about dome arch breaks but now am reading through threads to learn more. I am trying to find pictures to better understand how to incorporate one into my build but haven't found any posts with specific pictures of the arch break. If you know of any, please let me know. There has got to be some pictures on this vast site. I will look and post what I find for others who may use my thread as a build guide in the future.
How thick does the break need to be. It sounds like while casting my oven, I can just put a piece of cardboard in between the oven and the flue gallery (so they aren't attached) and fill it with a thin layer of perlcrete or mortar? How thick should it be?

[mrchipster]

Re: Starting my build

Just the slightest gap is all that is required. A single layer of corregated would work great. I did not cast my oven so I have not done research on them specifically but look at the cast Forno ovens on their site they gave exploded views and that should provide some guidance.

[almondsurf]

Re: Starting my build

I was looking at the exploded views of FB ovens (which look great). But they have no brake. Most come in 4 sections with the flue gallery built in. That's okay though, doesn't mean I cant build a brake into mine.

I know nothing about flues or the oven ventilation. Do you guys think "this" will work for my flue if I just mold perlcrete around it to hold it in place and stick a rain cap on top? Seems like it should work but what do I know.

I was thinking about casting about 1' of the flue (with out actually using a pipe to line it) with the refractory mix, then put a pipe (like the one in the link above) on top of the casted 1'x6" flue hole and use some of the insulating pcrete to hold it in place, then through a rain cap on top. I hope this is making sense.

Thoughts?

[almondsurf]

Re: Starting my build

I thought I would post some progress I made today. I decided to go ahead and cut the brick using the circular saw. It worked out quite well (I think). I just soaked the bricks before hand for around a minute or until there were no more bubbles coming out of the brick while in the water. Then I used a clamp to hold the brick to a board and did my cutting. I didn't apply any water to the blade as the dust was relatively minimal. It did kick up a little dust though, should have used a respirator rather than the little $1 insulation mask I had laying around. I thought it was much better than buying or renting an expensive 10" tile saw.
I hope to be casting the oven by next week. My needles and blanket arrived in the mail a few days ago.

Notes:
-The fire brick in the pictures is not in its final location, I still have to put down sand and level.
Thank you for all of your help and suggestions so far!!!
-For anyone who tries this method, be aware that the bricks are a LITTLE more fragile after soaking them. Just something to be aware of.

[almondsurf]

Re: Starting my build

Question...

I placed my bricks on my insulation where I thought they ought to be (took about 2 hours because I had to level each brick).

I noticed after I was done that the front of the oven hearth is a little crooked / turned. The bricks are in the right spot, but the oven is just turned a little to the by about .75 inches (19 mil.)

Do you guys think I should relay these bricks to get it more exact???

The bricks extend about half way into the flue gallery, then I am going to cut a slab of granite today or tomorrow that will extend the rest of the way out to the front of the oven. I plan to cast the oven this weekend, so I need to move relatively fast if I'm going to take the time to redo the brick hearth.

[mrchipster]

Re: Starting my build

From photos it looks a little clockwise from where it should be. It will not kill anything but then again two more hours to reset is not that long to get what you really want.

[almondsurf]

Re: Starting my build

Thanks chip!! It was turned slightly clockwise. So that's what I did last night, put the puzzle together again. It's still not exact, but it's pretty close. Thank you again for your speedy reply.

[NCMan]

Re: Starting my build

Looking good, almondsurf. Like you said, it didn't take long and you'll be glad you redid it.

[almondsurf]

Re: Starting my build

Over the long holiday weekend, I managed to carve out my granite entry piece and put the inner dome together. My wife and daughter helped me along the way. A good wife is worth... well... everything. She kept saying, "I sure hope this is worth it." Inside I kept saying, "I sure hope I don't screw this up."

I thought this would be pretty straight forward, but of course, it was twice as difficult and took twice as long as I thought. The actual sand dome was pretty easy, but the sand flue gallery was more of a challenge. I started with the sand flue gallery; I don't think I had enough water in the sand as it was falling all over the place. I increased the water ratio for the dome and it went on quite well. I chopped up some old 2x4's as a filler so I didn't need so much sand. The newspaper was a (expletive) to put/keep on. The wind picked up and we had to replace all the wet newspaper about 3 times! Then my wonderful wife had the bright idea to make a temporary glue (1.5 part water, 1 part flour) to lay on the newspaper to hold it in place. This worked like a charm. Too bad I was over half done by that point.

I made a quick tarp pyramid the day before so I could have it slow dry to avoid cracking. Sorry, I forgot to take pictures of the final oven before I covered it. I added some mix about a foot up the flue (the pipe in the picture was just for a form for me to build up 1' tall around it).

I mixed the cement layer quite dry so I didn't encounter the "slumping" on the sides of the oven as other casters have mentioned. I think it was just enough moisture to make it bind, but not too much as to weigh it down (not sure the ratio). I'm going to leave it tarped for a week. I guess we'll see if all this worked.

Question:
How long do you guys recommend I wait until I dig out the sand, and for it's first small fire?