40" pompeii, first time builder

[david s]

I’ve not looked at those numbers really closely because I’d be doing it in metric, but they look about right to me. Ofcourse there’s a difference in dry and wet mass as well as some loss in volume once you mix water to dry materials, as they compact. Because the ingredients for the homebrew are so much cheaper than proprietary castable, the cost is hardly an issue.

Oops, I just re-read your thread and realised you plan on using proprietary castable, in which case it should have the burnout fibres already added, so no need to purchase them separately. If you want to add reinforcing fibres though, you’ll need to add those.

[totalnewbie]

I haven't given up on the idea of finding CalSil board in the US at a reasonable price. If there is anyone out there with tips on where to buy CalSil in the mid-Atlantic/DMV area I would appreciate the tip. Thanks!

[Giovanni Rossi]

I guess it depends on what you believe is "reasonable". You're paying for improved performance / thickness and avoidance of prolonged drying time over perlite/vermiculite concrete insulation.

There are suppliers out there, but shipping costs can be high (as with most things today). Distribution International is well represented in that region. I seriously considered picking up my order of FOAMGLAS at a location 3 hrs from me, but the cost of fuel and the thought of burning a whole day changed my mind. The net cost savings just wasn't worth it to me. I guess you could consider picking up from them or another supplier, if the numbers work for you.

I don't think there's much wiggle room on product price.

[UtahBeehiver]

Plus one on Gio's comment. In the scheme of things, effective insulation is one of the "most" key components of a good oven performance. You can try Distribution International, there are branches in your area. You also ask it they have any freight damaged or shipping returns on CaSi at a better price. Thermo Gold 1200 is a common CaSi and the new versions are water absorption resistant.

[david s]

Russell, have you ever tried the water resistant stuff? It isn’t available to me so have no idea to what extent it is waterproof. I wonder how it would stand up to being immersed in a bucket for some time?

[totalnewbie]

I got a quote for Armilcfs for about $400. $88 each (2x18x24"), so $264, plus, $133 shipping. I have a request into Distribution Int'l. They're close, so I can pick it up.

I can do 4"+ of vermiculite concrete for $100-$150. And it works well.

I'll report back with what Distribution Int'l has in stock. I think they carry multiple product lines.

[totalnewbie]

I called my local Distibution Int'l office and they don't stock Calcium Silicate board. This is lot (lot) harder than I would have thought. it seems like nobody is interested in serving the DIY pizza oven market. :-(

[totalnewbie]

Quick update. I ended up buying vermiculite from a garden center. $40 for a 4 cu ft bag. All good!

And a question. I've been scouring the forum for ideas on how to form/frame so I can cast the vent. I want to do something like FB's own ovens with the square, flat vent that hods the anchor plate. I remembering seeing that someone did a really nice job of that in the past and they posted good photos of their forms, but I can't a good example. Any tips or someone remembering those thread would be really appreciated. Thanks!

[Giovanni Rossi]

Searching in the Forum can be tough. Try a Google search. Something like: flue anchor plate site:community.fornobravo.com.

Play with search terms. You can also refine the search with the Tools function and use a custom time frame if you want the most recent posts.

[david s]

Look at this thread starting here

https://community.fornobravo.com/for...723#post435723

[WaterDog]

Here's another interesting thread showing a molding form using rigid foam insulation. I can’t speak to the process as I haven’t cast mine yet but I have built the form and the material is relatively cheap and very easy to cut/shape. I plan on covering the completed mold with packing tape and wiping on some WD40 as a release agent.

https://community.fornobravo.com/for...tand-dallas-tx

See post #11

[totalnewbie]

I'm always so impressed by the great things builders do! These were all helpful suggestions. Thanks. My vent is going to be hidden behind the enclosure, so no need for beauty, But square that lines up with the anchor plate would be nice.

Giovanni, using Google to search a website was really smart. I should have known about that for years. It's far better than the forum search function.

Here's a new question. I've seen foam and metal, Does anyone have a crafty idea of an easy way of getting a 6" round object to cast the vent opening. I was thinking coffee can. What about using the chimney section itself, and wiggling it free as the casting material is setting?

[david s]

Here's another alternative which has the advantage of low thermal mass that won't act as a heat sink like a heavy brick or castable casting does. You will need to get it fabricated at a sheet metal shop who have stainless welding experience (unles you do) The stainless should be 0.9mm thick 304 (or specify 316 if you want to be crazy)
Regarding the use of something to cast around if going the castable route, the pipe itself works fine, but be careful to wrap some cardboard around it, then some sheet plastic for easy removal. If the castable is too tight around the pipe you risk cracking the casting from the expanding conductive pipe.

[totalnewbie]

That's a nice idea. I've spend some time on that website getting an idea for proportions. But I don't have access to a metal shop. In fact, I contacted a couple of local fabricators for the door, and got a quote for $300 for a simple powder coated door. hahahahaha.

[totalnewbie]

Is there a best practice for whether I should cast the dome on the brick floor or directly on my vermiculite insulation layer? What are the trade-offs, pluses and minuses, for the two approaches?

Does a cast dome sink of you cast it on the insulation layer?