Starting my build

[almondsurf]

Re: Starting my build

it depends what you want your oven to do, but if you are not planning on baking bread for the neighborhood then 2" is perfectly adequate for a family oven. Most manufacturers seem to make their castings around this thick.

Thanks David S. I was hoping I didn't have to cast this thing 5" thick.

[SableSprings]

Re: Starting my build

Hold a peel, rake, ash shovel and some cast iron pans/pots at various heights and think about accessing areas 50 - 60 inches away from where you are standing. You can do this with boxes and books stacked on your kitchen counters. It will help a lot. Remember you will be viewing and working through a half circle tunnel that is very close to you.

Chip, I think yours is the best solution to the personal issue of "How high should my hearth be?" I think the range of options and inches high is very personal and variable, so my "Belly button high" is really just a starting point. Doing actual practice with day-to-day oven operation simulation as you suggested is a fabulous way to differentiate what you think will work and what actually WILL work! Great input!

[mrchipster]

Re: Starting my build

mrchipster,

Chip,

Greatly appreciate your two cents...sounds like I'm on the right path (thought process, ie; higher is better than lower)...I'll take a look at the drawings again with your thoughts in mind!

It's the journey...not just the destination, that makes this fun.

Hold a peel, rake, ash shovel and some cast iron pans/pots at various heights and think about accessing areas 50 - 60 inches away from where you are standing. You can do this with boxes and books stacked on your kitchen counters. It will help a lot. Remember you will be viewing and working through a half circle tunnel that is very close to you.

Attached are the work ends of my pot moving tools. The top one works great one hook pushes the other pulls on the loop handles of cast iron pots and pans.

[cook4fun]

Re: Starting my build

mrchipster,

Chip,

Greatly appreciate your two cents...sounds like I'm on the right path (thought process, ie; higher is better than lower)...I'll take a look at the drawings again with your thoughts in mind!

It's the journey...not just the destination, that makes this fun.

[mrchipster]

Re: Starting my build

There are many comments on the forum related to the height of the oven floor. When I decided on where to put mine I found that rarely, people were unhappy with floors that were to high, but people often complained that their floor was to low.

I placed my floor 4 inches above my BB at 44 inches above the ground. I am 5-7.5 and find it easy to move things inside the oven and I do not need to stoop down to see anywhere in the oven. Next time you are in a pizza shop ask to see how high their oven are. They are always high or higher - never low.... Just my two cents.

[cook4fun]

Re: Starting my build

SableSprings, thanks for your email. I've purchased an oven here in Germany and will build it in the States, from Valoriani (mfg in Italy). Not nearly the size or capacity of yours, but something that will fit well for our situation.

FVR 110cm

Thanks!

[david s]

Re: Starting my build

David S: Do you think that a 2" dome is thick enough when cased? Or, does it need to be 3"+ thick?

Thanks again guys!!!

it depends what you want your oven to do, but if you are not planning on baking bread for the neighborhood then 2" is perfectly adequate for a family oven. Most manufacturers seem to make their castings around this thick.

[SableSprings]

Re: Starting my build

Sorry for the thread highjack almondsurf...

...Regarding "belly button" height, I have designed (but not built - that happens in two months) the oven floor to be at mid-chest height (about 10" higher than belly button height). I've read in lots of forum's that "I wished I had made it higher", so I'm thinking the route of going a bit higher - especially given the angle that we have to bend at the waist. My plan is to use the FB Cucina stand (40") placed on top of a 6" slab (totalling 46"), 4" of perlite / portland mix @5:1, (50"), 2" of FB CalSil board on top of that (52"), and then the oven hearth 54"). I'm 5' 10 (and a bit), but 57 and can no longer bend like gumby the way I used to...your thoughts are greatly appreciated.
-

Cook4Fun, I don't know how big your oven is going to be, but the higher you go, the more you will limit easy access into the oven. And it's exactly the same problem if you go too low. Putting pieces of wood into a center or back fire or lifting a dutch oven and pushing it back will be a little more difficult the higher/lower you are from your normal working range...but you probably won't hit your head on the entry arch as often as I do and there are lots of tools to help move things around in the chamber. The belly button height recommendation is just my opinion of the optimum height for most folks. Loading wood, moving food items (and their container pots) around the chamber, and cleaning out the ash are things I would think about when determining the hearth height. Since you're sounding comfortable with a slightly higher hearth than mine...no problems, remember your oven is uniquely yours.

During construction, make sure you've got a sturdy ramp of some sort to move all the materials up to the oven construction zone. That can be a real challenge to move buckets of insulation perlcrete into the form as well as the mortar and bricks up to the platform...any younger folks around that you can do a Tom Sawyer/Huck Finn routine on?

As long as you are comfortable with working a peel and doing the oven firing processes at a higher level than "belly button height", it will work just fine. (As an aside, I did buy a 12" cast iron frying pan for making brick chicken soon after I built the oven. Unfortunately, I could barely maneuver it once I put the pan--filled with flattened chicken and two bricks--onto the oven landing...I was so afraid of sliding on my firebricks and damaging them, that I was trying to lift it back into place instead of just sliding it. At the time I felt that I had built the hearth too low!)

One comment about the foundation slab you're planning on putting on top of the FB Cucina...I think 6" of reinforced concrete is overkill. Most of us only have slabs of 4" or so. If you reduced that to 4", I think you'd still be good at a final 52" height.

p.s. I'm just under 6' tall and almost 64 now. I certainly got a chuckle out of the Gumby comment --thanks for the smile

[almondsurf]

Re: Starting my build

Thank you so much guys! The video helps me to see the consistency of the mix. I probably would have added more water if I had not seen that video. I will try to get it close to that 1/3 per David S.

David S: Do you think that a 2" dome is thick enough when cased? Or, does it need to be 3"+ thick?

Thanks again guys!!!

[cook4fun]

Re: Starting my build

Mike - I really appreciate your insights regarding the construct of an oven, especially the perlite / concrete ratios and the height of the oven floor. Regarding "belly button" height, I have designed (but not built - that happens in two months) the oven floor to be at mid-chest height (about 10" higher than belly button height). I've read in lots of forum's that "I wished I had made it higher", so I'm thinking the route of going a bit higher - especially given the angle that we have to bend at the waist. My plan is to use the FB Cucina stand (40") placed on top of a 6" slab (totalling 46"), 4" of perlite / portland mix @5:1, (50"), 2" of FB CalSil board on top of that (52"), and then the oven hearth 54"). I'm 5' 10 (and a bit), but 57 and can no longer bend like gumby the way I used to...your thoughts are greatly appreciated.

-

[david s]

Re: Starting my build

I've found the correct ratio of water is 1/3 of the volume of vermiculite or perlite. If you add too much it pools in the bottom of the barrow and tends to wash the cement off the grains of perlite. Also if you use 50% vermiculite and 50% perlite it makes a more workable mix than either of them alone. Also adding a small amount of powdered clay to the mix helps make it more workable. I use a handful for every 10 litres. Because around double the amount of water is used than is required for the hydration process, there is no need to keep wetting the stuff down. Just cover it for 24 hrs then allow it to dry in the sun and wind, if you have any. It will take about three weeks to dry out in ideal drying conditions.

Trying to dry it with fires alone after building straight over it is a bitch. It will takes many weeks and fires to eliminate all the water. Some holes through the concrete supporting slab between the vermicrete and the storage area under work well to help this moisture escape, particularly if it gets wet again after heavy rain.

The doc on this post may help you.

http://www.fornobravo.com/forum/f2/vermiculite-questions-19701.html#post158957

[SableSprings]

Re: Starting my build

Here's a link to a perlcrete mixing video. The thread is on the Forno Bravo site somewhere, but I thought since I had this it would help you for the upcoming work.

https://www.youtube.com/watch?v=1Ot8vucmVis

Yes, the final mix when correctly mixed seems a bit dry...you should be able to take a handful, squeeze and it will hold together. The wheelbarrow & hoe combo is great for mixing. Make sure that you mix the Portland cement into the perlite first. When you add the water it will actually wash the cement off the perlite...that's normal. A little mixing and it comes back together. The biggest issue is making sure that you mix water in very slowly and completely before adding more. I used a watering can to make the water additions a little more gentle. My water source was the 5 gallon bucket, so I could keep track of how much I'd added.

In the video, he gives you some estimates of water used. Note that having some extra perlite and cement on hand is good...you're going to be using some again later, so don't get caught short on supplies.

NCMan is correct, don't soak things down, just keep it moist while the curing process is underway. As he suggests, the plastic covering (with maybe a piece of plywood on top to keep it in place) will probably be all you need to keep it moist if it's under shade.

Be aware there is another method that combines the cement and the water first, and then the slurry is added to the perlite and mixed. I have no clue on water proportions so I'll suggest you continue with this method until you get a hankering to experiment...

[NCMan]

Re: Starting my build

I think you'd be better off just covering it w/a sheet of plastic and then some cardboard or plywood. I'd leave it that way for a few days or even a week or so. Just like concrete, keeping the mix water in the slab, not watering it down, does a lot more to strengthen a slab then soaking it down does. After you do uncover it, allow it to dry a bit before moving on to installing your hearth bricks. Just my 2?.

[almondsurf]

Re: Starting my build

Thanks so much. I am going to pick up the base insulation today. I hope to be working on that by this weekend. Is the v/p create supposed to be an oatmeal texture? I was wondering how much water to add?

I am quite worried about casting in this dry climate after what happened to the slab. I was planning on watering it at least 2 times per day. I figured I'd just wet it down, then cover with a tarp, then wet, then cover.... for a week or so.

[SableSprings]

Re: Starting my build

Rather than casting your oven in the garage and then trying to move an unwieldy shaped +400 pounds into position on the stand...Borrow a shade canopy and cover the casting work area of your oven stand/foundation/slab. It will make your life a lot easier working in the shade. Remember you will need to do your insulation slab at least a week before setting your hearth bricks and starting to cast on top of it.

Next cover the insulation slab pour with plastic immediately after you fill up the form. With your dry conditions, make sure all cement & castings are dampened and covered with plastic whenever you aren't actively working. Wet down the casting material daily and when you've completed it & make sure to keep it damp/wet for about a week as it cures.

For you the plastic cover and daily watering will be critical to keep the mixed cement products from drying out too fast. Cement needs water to cure, it's actually forming long, microscopic crystals in the slab during the week or more of curing and needs the water to form and set those important internal structures. Remember that the perlcrete/vermicrete will also need to be kept cool/damp for a week or so to allow the binding cement to set properly. (By the way, this insulation material is really weird stuff...you'll think in two days that you screwed up and then in 4-6 days it firms up enough to remove the forms. It will always be crumbly, but it has great compression strength and will easily support the hearth bricks & dome casting--so, no worries.)