42" Pompeii construction in Adelaide

[P3 Stoaker]

G'day All,
Wow, the time has come to start the build post. I have commenced the base support and plan to lay the hearth soon. Many thanks to UtahBeehiver, JRPizza, mpmckenzie, chach and david s who have provided terrific info so far. I certainly hope to continue learning from the forum and in turn pass on to those building in the future.
I do have a couple of questions and certainly appreciate the responses;
1 Searches suggest this is the best place for an ongoing build post. Please confirm this is still the case?
2 What is the purpose of a 'heat break'. I have seen in floors and have I seen rope seal heat breaks in the entry arch?
3 I've read lots and lots about dome on and off the floor bricks, however, what could possibly cause the need to replace a floor brick, right out on the edge? Also, the lower section of the dome would need to be vertical to allow installation of a new floor brick??

Kind Regards

Greg

[P3 Stoaker]

G'day Again,
Thought to post picture of the base brick work for those that haven't seen as yet. Centre section is almost 80" square and sides are 40" wider and 60" in length from the back.
I'm looking at an 8 " stainless flue and saw a good application where the adapter plate was screwed/bolted to an upper horizontal surface of brickwork above the entry. I plan to go this way as it seems like a good way to minimise water entry near/adjacent the flue and with an outside oven will allow replacement of the flue nice and easy. Looked on line without luck. Anyone know of availability in Adelaide, or Australia?

Also, I've seen pictures of quite long entry's to ovens and would appreciate thoughts on how long is too long? I'm thinking of an inner arch (either around half, 4.5" or possible a full brick and either way it will make the reveal), a full brick,(9") reducing to half at the top for the opening, and a red frontage brick around 9". this totals 18" outside the inner arch/reveal and probably additional 4.5" for inner arch, totalling 22.5". Seems like a long way to look in? Any thoughts/comments appreciated.

Kind regards and many thanks.

[UtahBeehiver]

1. Pompeii Oven Construction
2. Reduce heat transmission in bricks from dome to vent. There is much discussion on whether the effort is worth the heat savings. I did it and does it make a difference, don't know. But what I can say, floor, dome, and door insulation will make a more substantial impact on heat retention.
3. Your choice, in the hundreds of ovens I have seen, only one maybe two have ever had to replace a brick. dome on floor takes less precision floor cuts.

FYI, your last question, the inner arch, if you do a tapered inner arch (recommended) will require you start out with full length bricks and are cut down but longer than 4.5" bricks, a full length brick vent chamber is not uncommon, then you decorative outer half brick arch is also common. You want to see a deep entry, look at Gulfs, it is very deep and it works for him.

[david s]

I’d endorse Russell’s response and add re heat break, which is an idea I brought to this forum many years ago from Rado (Traditional ovens) that the heat break will slow down heat transfer by conduction, but little by radiation because it’s only a small gap. It’s primary function IMO is to act as an expansion joint. This helps Niigata the problems of uneven expansion caused by the higher temperature of the oven as opposed to that of the flue gallery. In my own design because my flue gallery is a cast section rather than brick, it is far thinner and lighter and does not present the same kind of heat sink issues that a brick one does. Consequently my heat break/expansion joint is situated between the flue gallery and the outer decorative arch. In this position it protects the decorative arch from expansion pressure from the inner oven parts. The cracking of the decorative arch, I’ve seen in many ovens is testament to the lack of consideration to this issue.
Regarding the depth of the flue gallery, it is very difficult using brick units to make it shallow. In addition it seems impossible (at least I’ve not seen any solutions) to tie the corners in using bricks. This creates structural weakness should any mortar joints fail.

[P3 Stoaker]

G'day All,
Many thanks for the replies. If I may;
Russell, I have seen a few posts on the tapered inner arch and I don't mean to be negative, but I must admit with my knowledge, nil option of drawing programs, and available info I'm not sure how to tackle that one. At the moment I'm looking at the overall layout details in consideration of the hearth and insulation, as you have assisted with and while there is ever a recommendation, as you have done relating to the taper arch, I will certainly have a good look, so thanks for the advice.
David, insulation of the outer decorative arch definitely looks like worth planning in, given its a main focal point. I do wonder how to tie it to the main arch though? I lost you though discussing the flue gallery, is that the entry outside the inner arch? I'm happy to make as long as needed, just wondering what others think of 22.5 inch? Not sure what you meant about tying corners in using bricks?

One thing I haven't seen is some tying/connection of the outer arch to inner arch. I have quite reactive earth and whilst my slab is 8 inch with double layered mesh I still expect movement. I guess trouble tying the arches together is it would need brick courses to align which may not happen and in itself could invite cracks.

As mentioned in earlier post, if anyone knows a good supplier of stainless flue and base plates in Adelaide please let me know.
Comments and advice always welcomed and appreciated.
We should have international pizza week where we all go mad cooking pizza at the same time. Can we wait a bit though, i'm a while away, Haha, or I'll go to brother in law"s house !!!!!
Kind Regards

[NCMan]

I personally am a big fan of gaps between the arches and between the oven floor and hearth landing, both as a heat break and an expansion joint. Yes, they make a noticeable difference in both applications.

[UtahBeehiver]

You do not need to be proficient if CAD or drawing to do a tapered inner arch. It is done with the IT tool. That said, it is a difficult concept to visualize but not to hard to execute. The light bulb comes on once you start laying things out. It is well worth the effort and makes the ties to the dome and inner arch much easier.

[P3 Stoaker]

Thanks Russell, I think I get it more already, the tapered arch that is, and I'm somewhat sure I'll have a working brick saw for the duration, which I think would make some of these more tricky cuts manageable. I was given a 20 year petrol saw which ran but was clapped out and vented all it's crankcase oil very quickly and was the dirtiest thing I think I've ever worked on. They were a poor design with the air filter at the front so over time it sucked in dirty water. The carby was full of dirt. Anyway I've done a full engine rebuild up to hone, rings, all bearings, valve re-seat etc. I was happy when it ran with a single pull and I did a few heat cycles over the next day or two. Went down the shed other day and it had been leaking a fair bit of oil. After a good look I found the crank case to be cracked, bugger!! Anyway I've dismantled again and used some liquid metal to repair. Should get another start tonight.

I'm about to work out how I'll make the IT tool, lots examples seen in numerous posts.

I'm close to finalising the entry. I'll have the full brick (at the bottom) tapered inner arch. Outside the inner arch is where I need to finalise. I'm using a 9 ' brick. Noting what you said earlier, 'full length brick vent chamber is not uncommon', by that do you mean the actual opening rising up to the flue is a full brick long? For info I plan to raise bricks above the arch a little to a flat top and then use a flat base plate and metal flue. In that case thinking of that part of the opening possibly 1.5 bricks at bottom, reducing to half a brick, creating a full brick length opening in the upper section, on the side nearest the inner arch. From there would have half brick decorative arch front in coloured brick, red. So that is 3 bricks long, some 27 inch. I would appreciate readers thoughts on the 27 inch opening length, as well as the overall plan.

I'll get more photo's up when I work out how to reduce their file size, most are rejected for being too big.

Regards to all

Greg

[UtahBeehiver]

It is hard to visualize what you are doing, dry layout the base course and take a pic and post.

IT - Critical items.

1.Pivot point needs to be at center of floor and as close to floor elevation as possible (wood brick cutout is used quite often - see Gulf's build)
2.Pivot point and along center of IT rod to the "L" bracket needs to intersect the horizontal center of your brick, ie if brick is 50mm thick then center is 25mm.
3.Make sure IT rod is adjustable in length, a couple inches either way of dome radius is fine.

[P3 Stoaker]

G'day All,
Many thanks Russell. I started the IT tool today, should be well worth it .

I've started getting my head around the tapered arch and as you say the IT tool will help that along.

Good idea to post picture regarding the oven entry, inner and outer arch. Whilst I welcome any thoughts/comments I'm specifically seeking thoughts about the length of the entry, from inner tapered arch to outer decorative front. Please disregard some of the bricks, just some halves I have as I haven't started cutting oven bricks yet.

So looking at photo, I'm thinking half red decorative front (4.5 inch), then 1 and half bricks (13.5 inch) to allow vent and 8 inch stainless flue to sit on base plate then the offset for the reveal can be seen on the photo and the inner arch ( a bit less that a full brick of 9 inch, so lets say 7 inch). That totals 25 inch. I'm happy for it to be what it needs but seems quite long so thought to ask the question?

I'm looking at the 1.5 brick length ( the 13.5 inch) for the vent (not sure on correct terminology but the opening to the flue) based on a whole brick opening next to the inner arch and the half actually being there, meaning the red decorative will be up against the half. I note above you mentioned a full length brick vent chamber is not uncommon, any suggestions, full or half?

Kind Regards and many thanks.

Greg

[UtahBeehiver]

Just to make sure, none of the bricks in holes in it are being used in the dome or floor. I do not think you need the half white brick next to the red half brick.

[P3 Stoaker]

G'day All, I did ask in another post with nil responses in relation but is anyone fitting temp probes when building ovens these days? The infrared temp hand gun probes are not too expensive and can quickly measure temp of any surface. I assume when checking oven temps one could do so in a few consistent positions thereby reproducing temp readings from those same area's and getting to know what works, from one use to the next. Thoughts/recommendations appreciated.
Kind regards
Greg

[P3 Stoaker]

G'day All, time for a progress post, and couple of questions for anyone with time.
I've read it a thousand times and am now experiencing it for myself, little forward with plenty of going backwards as well (hopefully less though).
Finished the IT tool today and cut the first bricks yesterday. The brick saw was given to me and needed HEAPS of cleaning and a full rebuild. The case crack and subsequent oil leak mentioned above is holding together for now.
Chasing info on;
1 Is it important which way the half bricks for the dome sit, ie, cut inside or outside. I'm not sure if the kiln fired original uncut side should be facing inside towards the heat?
2 I'm laying mosaic tiles under the calsil board, Is 5-6 mm (3/16 inch) is thick enough. Seems thin but to go thicker they become stone and super $$$$
3 Any tips on how to draw an arch opening, so I can copy to plywood for the template? I'm going for 12" high and 19" wide which seems fairly standard but with a width radius of 9 and half inch and height of 12" its got me wondering how to draw it and subsequently shape it?
4 And finally, the arch position, back and forward relative to the dome is causing me grief, doing my head in. I've saved heaps of photo's and spent hours looking at this and I "think" I've got it but I'm not 100%. See in the photo, the top brick up on it's side is at the correct height in relation to the IT tool, and that's a little marker in the holder. The outer most end face of that top brick is just inside the outer dome radius, at floor level. Obviously, that top arch brick position governs the lower most arch brick. Have I got it right

Many thanks for the thoughts and comments, greatly appreciated.
Kind Regards

[Chach]

Now that's what I'm talking about. Nice score on the saw! What's the diameter of the blade on that bad boy!

Ricky

[modified9v]

Couple things... I had all the same questions you did and I think they were answered pretty well on my thread. I will say that I was concerned with putting the cut face inside toward the fire. I did one chain that way for looks only. I don’t think it matters.

You will figure out that reach of the inner arch, I promise. I never thought I’d figure it out but with the help of several members I felt confident and it worked out. I was skeptical but went for it... use the IT to figure the TDC brick and work down from there. I made it way more complicated than it needed to be.

Mikie V