36" Pompeii Dome - Thailand

[danhem]

I think you should be fine with the caster, reducing your radius/length of the IT as the angle of your IT vs. the floor increases with each chain.

I started my first course flat in the same orientation as the rest of the dome bricks because it seemed simpler and I like how it 'pulls in' the ceiling closer to the pizza around the edge of the oven.
Started outside the floor bricks because that first course provides a bit extra heat mass and insulates the floor horizontally.
Cutting the outer floor bricks to get that rough circular shape was not that difficult. 2 to 3 cuts per brick.
I ended up cutting a LOT of bricks where it wasn't absolutely necessary to reduce mortar gaps and increase the total mass of bricks in the oven. Downside is I'm on my 3rd $50 saw blade.

Again, I'm no expert, just passing on what I've encountered. Good luck and stay safe. Post photos of your progress.

-George

Thanks George,

We spent a part of the morning looking at the IT and its function to try and determine whether the Caster pivot would hamper us as we progress through the courses. Seems that the IT will be ok after paying around and dry fitting a three-course section.

The vast information on the forum can get a little confusing due to the variation on each build, seems that there isn't 1 perfect way of doing it. Heading back out there now to trim my ceramic fibre board and to lay the oven floor.

Looking ahead I'm already nervous about the arch ways and need to get a grip on understanding the taper/angle cuts of each course brick. Definitely learning as I go along and also definitely learning the hard way.....having the time of my life though

[UtahBeehiver]

Tapered inner arches is the most difficult concept to understand and visualize but worth the effort. Attached is overview of how the IT is used to determine the various angles of a tapered inner arch.


It is just an overview, when you ready I will give you additional info.

[danhem]

Tapered inner arches is the most difficult concept to understand and visualize but worth the effort. Attached is overview of how the IT is used to determine the various angles of a tapered inner arch.


It is just an overview, when you ready I will give you additional info.

OK great, I did see this image on another post and didn't pay too much attention to it at the time. After a closer look it does make some sense, no doubt I'll be back on this topic when I get that that stage.

About ready to lay the oven floor on top if the insulation board. Before I begin, I have the following Qs:

1) Have I cut the insulation board correctly? The dimensions in the attached image are correct (my photoshop skills are equally as bad as my brick laying skills) and feel that the diameter is fine, but I'm not sure about the width of the landing area. At 26" is this too wide for a 36" Oven? I can lay the brick in header form to narrow the gap leaving an opening width of 17".

2) Conflicting info on the forum with regards to the Soldier course. I am planning a Soldier course to sit on top of the over floor cut at 4.5". I'm assuming this method is fine?

3) Does the top edge of the Soldier brick need to slope to accommodate the laying of the 1st course?

Thanks as always.

Danny.

[UtahBeehiver]

1. Width of the landing is builders choice and not critical as height of the inner arch opening which should be 63-65% of radius of dome height. IE 65% of 18" = 11.7".
2. Half soldier is fine. Full height soldiers may require buttressing.
3. I have seen both ways.

[danhem]

2. Half soldier is fine. Full height soldiers may require buttressing.
3. I have seen both ways.

I was about to set the Soldier course today but wanted to do some final checks on the IT and how the 1st/2nd/3rd courses would sit. It looks like the IT will ned to be adjusted slightly for each course to maintain the 18" inner radius - not a problem.

A major problem that did arise however was that it looks like I will need to slope the half-Soldier to maintain the 18" radius throughout the courses. Standing the half-Solider without a slope seems to push the first course away from the 18" radius distance. I can cut the half-Soldier slope but am currently waiting for a masonry blade to arrive (could be weeks under the current Covid circumstances).

At this stage I'm at a real cross-roads. I made a guide as can be seen in the picture (joint angles are out but as a rough guide I can see how it could work). Laying the courses like this would maintain the 18" inner radius and would more importantly save me a lot of time in cutting the slope on the half-Soldier layer. I am now looking at laying the first layer flat to the oven floor.

The question is - Is there a significant/any advantage to laying a half-Soldier course (4.5") instead of the bricks being laid flat (header?) at 2.5" all the way up from the oven floor?

[danhem]

Had to revisit the IT - something was not sitting right with me. Too many alterations as the dry fitted courses progressed and too many discrepancies with the angles and radius. I've gone from half-Soldier to half-header and back again trying to work it out but each time the results are off - this is not what the IT was intended for.

Seems that the problem has been with the raised pivot point that is too far from the oven floor and therefore throwing the brick angle off and the perpendicular point away from centre. I've lowered the pivot point by creating what effectively now looks like a double barrelled shot gun and it seems that the IT is now perfectly (almost perfectly) aligned and is functioning how an IT should function. I was trying to replicate another more practical design but was unable to source the parts as the stores are shut.

A long slog with the IT. I can now begin to work on the inner-arch with more confidence knowing that my IT will account for much of the work - wish these things were available on Amazon.

Cheers,

Danny.

[danhem]

First day in many that I felt a breakthrough had been made. Finally began to lay the courses and in part was very pleased at least with how the brick work looks.....but, and a huge BUT......the mortar I am using is really strange and I have little faith that it will set properly.

I know a couple of the other Thailand builds have used the same mortar and have faced difficulties with it. Seems that the mortar works best when the joint gaps are around 2mm think. I think david s commented on the technical properties of it and indicated that it was less than ideal for an oven build. Another case of one step forward three steps back.

So I will now begin to research the home brew style and hope that the ingredients are readily available here in Thailand....I'm expecting some downtime and that is gonna really p**s me off as I've spent a number of days trying to work out the IT and was glad to be free of that torment. Anyway all good fun.

Knowing that my brick cutting machinery is far from ideal to taper each brick to make narrower joint gaps, and my mortar is like jelly, I have turned my attention onto the inner-arch and very hurriedly made a form to see how it would sit. The pictures are not the best but my first thought is where do I position the form in relation to the outer radius of the oven opening?

** Edit - Regarding the mortar - woke today to some pretty hefty crack in the back joints. The bricks seem to be set solid after trying to dislodge with a reasonable degree of force. The mortar was still pliable so it squashed the mortar further into the joints to close the cracks and left them be during the day. The mortar is now setting very hard.

It doesn't sound like a best practice but I wonder if my strategy here is to fill joints with mortar, compress once cracks appear, then fill the gaps in again. just trying to work with the materials I have got knowing that the alternative options are near zero.

A bit of googling suggests that the wet refractory mortar comes into its own during the curing process. With luck on my side I can complete the dome the begin to cure.

[danhem]

Inner arch - I can almost feel it but something isn't clicking. I have 3 courses built and the arch form to start with 3 bricks in header position. Seems that to match the 4th course, the arch should begin to curve toward the top center of the arch, bricks facing the oven must be tapered to allow the 4th course bricks to run over the top of the arch taper? Apologies if this is not worded correctly but it's still a little hazy in my head.

Trying to use the IT to visualize this. I made a very rough pencil line to represent an arch brick cut that would flow with the IT.

I need to wok on the actual arch to make the fit as tight as possible. Based on the picture for my inner arch entry, is there a number of bricks I should look at using to make the tightest fit?

[UtahBeehiver]

Here is a pic of a tapered arch by MrChipster that is similar to yours. Notice how each brick is different and not linear but skewed. Remember you are after 63-65% of the dome height for the inner arch height, not so much the number of bricks to make fit. The flatter the arch the more outward pressure on the vertical walls, too flat and you may have to buttress the vertical walls. Also the placement of the arch form seems a little to far forward from the bottom vertical course. Notice in the pic that I sent you and this one as well where the bottom of the form lines up with the curve of the dome at the floor. Last thing, your start marking the tapered inner arch bricks at top dead center the work your way down left and right of TDC,

[danhem]

Here is a pic of a tapered arch by MrChipster that is similar to yours. Notice how each brick is different and not linear but skewed. Remember you are after 63-65% of the dome height for the inner arch height, not so much the number of bricks to make fit. The flatter the arch the more outward pressure on the vertical walls, too flat and you may have to buttress the vertical walls. Also the placement of the arch form seems a little to far forward from the bottom vertical course. Notice in the pic that I sent you and this one as well where the bottom of the form lines up with the curve of the dome at the floor. Last thing, your start marking the tapered inner arch bricks at top dead center the work your way down left and right of TDC,

Ok thanks, big help. The positioning of the form has been a head scratcher. Makes sense to position at radius point of the oven entry.

[JRPizza]

You just need to make sure the TDC arch brick sits within the dimensions of the shell of the dome like I drew in the link. There are a few inches of fore/aft positioning that will work - I chose a more forward position to maximize arch stickout. You just don't want to have to deviate from round when the dome bricks go over the top of the arch. In the attached link my opening height is 12.25 inches, so the brick shown is virtually sitting on my arch form.

[danhem]

You just need to make sure the TDC arch brick sits within the dimensions of the shell of the dome like I drew in the link. There are a few inches of fore/aft positioning that will work - I chose a more forward position to maximize arch stickout. You just don't want to have to deviate from round when the dome bricks go over the top of the arch. In the attached link my opening height is 12.25 inches, so the brick shown is virtually sitting on my arch form.

Ok thanks, I had seen that before and will pay closer attention to it now.

I had to laugh at some of the points you made in that particular post...."I think a lot of us come to the forum looking for "place it at X inches" and are disappointed that we can't find that kind of detail, but as cliche as it sounds if you can't figure it out yourself you aren't ready to build your oven"

Hoping to overcome this issue today, it's not really holding me back, seems that most others here have struggled with this exact same same concept.


Thanks again for taking the time to help.

Danny.

[danhem]

Feel like some sort of breakthrough has been made on my inner arch today. Visually the brick cuts pointing to the inside of the oven seem correct however they do look a little steep. I've used all the tools at my disposal to make the checks and i'm fairly confident that the next courses will fit nicely on top of the inner arch cuts. It's been a really difficult concept to grasp and the cuts were a challenge, so it feel like a major milestone has been achieved with this build.

Looking from the outside of the oven at the inner arch bricks, I do wonder how they will set once mortar is applied. I see many builds here that taper the bricks to create a tighter fit. Is this a recommended practice or does my arch have a chance of holding? I plan on applying mortar tomorrow and will leave it to set for a number of days before removing the form. Fingers and toes crossed at that point

I am also starting to understand what folks have referred to as the 'Inverted V'. As the courses go up the bottom joint of the bricks is becoming way too wide for my liking. I'll look top bevel the bricks from here on in to tidy those joints up for aesthetics and more importantly heat containment.

[danhem]

A huge day for me today after tapping the keystone on of my inner arch in place to see the other arch bricks crank tighter into place with each tap of the keystone. Definitely a day to feel pleased after last week;s problems with the IT and he inner arch concept itself. A few days of waiting time before dropping the form but I'm pretty confident that it could come out tomorrow without any issues.

Managed to continue with the courses and have pretty much competed course five with course six scheduled tomorrow. I began to try and bevel the bricks to avoid the inverted V. Not sure I've got it totally right but it seems to flow quite nicely on the eye. I hope to get better at this practice as the courses progress from here on in.

I defiantly plan on taking the next day or two easy and expect to complete course 6 and 7 before turning my attention on to the vent and outer arch - something that up until now has seemed a distant task.

I am also watching out the 'Dreaded Droop' - not really sure what this is but fully expecting to see it on my build at some point what ever it is

How the oven will eventually perform remains a worry but what I can say is how amazed I am at the sheer beauty of the dome as it grows, its curves and its angles. Truly worth the effort so far.

[Chach]

Nice! Yes I agree. when I built my dome and saw it coming together I was awestruck on how cool it looked. The more you keep building the cooler it looks because right now you see the way it looks getting fat and then it starts to narrow again as you close it up. I couldn't stop staring at mine. LOL.

Ricky