Starting my build

[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?

[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

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

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

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?)

[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!

[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

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.

[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.
.

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.

[SableSprings]

Re: Starting my build

I have been patiently waiting for this perlite to cure / fully dry. I figured I'd post a picture of the insulation layer without the form. It seems solid. I may put up a half inch or so layer of mortar around the outside of this insulation layer. Not sure if that is even necessary???

Should I use coarse sand or fine sand under my fire brick to level them out? I have bags of fine sand available in my garage, but would have to buy more sharp sand if that would be better. Thoughts?

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.

Builder's sand (sharp) is nice because it holds its shape better when you wet it, but the fine sand you have will work. Just remember to put down a 1/2"-1" layer, wet it, close level, then use a grout tool to put in some ridges on top. That way as you set the bricks you can tap them down to make the hearth level & firm. If you don't trowel in grooves you don't give the sand any room to move when you tap them down...same as when you lay tiles on quickset.

Sorry I don't have any comments for you on your casting materials list, but I'm sure those with experience will chime in.

[almondsurf]

Re: Starting my build

I have been patiently waiting for this perlite to cure / fully dry. I figured I'd post a picture of the insulation layer without the form. It seems solid. I may put up a half inch or so layer of mortar around the outside of this insulation layer. Not sure if that is even necessary???

I am going to go purchase all the ingredients for my casting recipe over the next 2 weeks. As previously posted... here is my recipe:
1 part cement
6 parts sharp sand
2 parts hydrated lime
1 part fire clay
4% 1" Stainless Steel Needles
1% polypropylene fibers

This week I will be buying my fire brick for my oven floor. I plan to cut them soon and will post what damage I can get done this week.

Should I use coarse sand or fine sand under my fire brick to level them out? I have bags of fine sand available in my garage, but would have to buy more sharp sand if that would be better. Thoughts?

[mrchipster]

Re: Starting my build

I did some cutting of granite this way and zip tied a 3 ft piece of 1/4 inc vinyl tubing to my saw. The other end was connected to a garden hose via some plastic adapters and a couple of hose clamps. It worked quite well and the water stream was always in the right place.

[NCMan]

Re: Starting my build

I would highly recommend a respirator for the both of you and skip the dust masks. If all you are going to do is cut them in half, you can simply score each one, turn it over and whack it w/a hammer. The rough edge goes to the exterior of the oven. No need to completely cut each one all the way through. It'll save time, a lot of dust and wear and tear on your cutting blade. Just my 2?.

[almondsurf]

Re: Starting my build

Almondsurf .. A circular saw with a masonry blade works well cutting the brick. If you want the beveled edges and etc., I would recommend the wet saw. If you end up just cutting the bricks in half, you could get away with the circular saw. If that's the way you go, soak the bricks in water for awhile to cut down on the huge amount of dust kicked up. Make sure to use a respirator or at least a dust mask either way. Good luck, it's a lot of fun either way.
Leigh

Thank you for the info Rodeair. I just purchased a 7" diamond blade at HD for $15. Thought that was a pretty good price. I will be using a circular saw as you mentioned. I will wet the brick as well as spray A LITTLE water on the blade as I cut. I will probably clamp the brick down to something and have my wife hold the sprayer. This way I should get a decent cut (maybe not the small ones) for each brick. I'll give it a go and report back if it becomes a success or failure.

[Greenman]

Re: Starting my build

Rodeair - Thank you. If I venture your way I will be honoured to catch up with you.