36" Pompeii Dome - Thailand

[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]

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]

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?

[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]

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]

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]

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

[Mongo]

Regarding the Caster - I am thinking that by measuring the hight of the pivot and reducing the arm length of the IT to make a total length from the pivot center to the base of the angled bracket 18”, then the radius will remain constant throughout the course?

The first course - Again my understanding in many builds was to lay a half-soldier on top of the oven floor. I see you laid your first course outside the oven?

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

[danhem]

Much better, but JR and Mongo are right about metal angle and width. I had two differ widths like Mongo.

Ok thanks. Damn I wish I’d have gotten round to making the IT earlier. It’s been a painstaking couple of day’s getting this one together. I think as it stands I’ll trim the wood to the width of the bracket and try to add as much strength and support to it.

I am a little unsure of the caster pivot. Say the pivot height is 1” above the oven floor, do I simply take that one in off the other end to make it a total of 18”?

Will this produce a consistent 18” radius throughout the courses?

[danhem]

I can tell you that I started with an all wood 'angle piece' and switched to one made of metal before I laid a single brick.
Found a construction tie at my local building supply that worked nicely.
I also second JR's comment that the angle piece needs to be narrower than the brick being laid.
I also second Russel's comment about the pivot point of the IT being raised from the floor using a castor.. I also started with a modified castor thinking it was the coolest idea ever but switched to a hinge after realizing the issue with the vertical diameter being different from the horizontal diameter.
Here's my construction brace angle piece, my hinge pivot and the trimmed down angle piece to accommodate the narrower bricks at the top of the dome.

Also looking at one of your photo's I think you may be considering a full upright brick for your first course. I'm not experienced enough to advise on that but do some reading/searching in the forum on the first course.

Just throwing out some ideas. Good luck!

Appreciate the response, thanks. I’m really hampered by what material I can use as the stores are all shut. I really wanted to follow JCG31’s design but I can’t get the pieces together right now. Sat at home with the stores closed for at least another month so I’m keen to move a head whilst I’ve got this time.

Regarding the Caster - I am thinking that by measuring the hight of the pivot and reducing the arm length of the IT to make a total length from the pivot center to the base of the angled bracket 18”, then the radius will remain constant throughout the course?

The first course - Again my understanding in many builds was to lay a half-soldier on top of the oven floor. I see you laid your first course outside the oven?

[danhem]

Two things come to mind looking at your pic's. You will need a narrower angle piece sometime during your build as the dome gets smaller in circumference and the bricks get narrower (if you decide to bevel and or avoid aligning vertical joints). It also looks like you may need to watch your angle bracket to make sure it does not loosen and fail to keep the bricks in proper orientation. Lots of us use metal for the angle which may hold up to abuse better than the wood you have chosen.

https://community.fornobravo.com/for...141#post381141

Thanks for your feedback.

I had planned to trim the wood down to the same width as the metal bracket.

as far as the angle goes, I’m really quite limited at the moment as all the stores are closed so it a case of issuing what I’ve got here in the yard. I did try to find a more substantial metal bracket online but my searches came away empty.

Ill be trimming down the wooden angle today and will apply araldite glue and some further wiggle support.

The center tubing is adjustable and can be removed from the fixed tubing should I need to/be able to make improvements to the angled holding piece.

It’s been time consuming getting to this phase on the IT but I appreciate from reading the forum that the more time spent here the better the build will be.

[UtahBeehiver]

Much better, but JR and Mongo are right about metal angle and width. I had two differ widths like Mongo.

[Mongo]

I can tell you that I started with an all wood 'angle piece' and switched to one made of metal before I laid a single brick.
Found a construction tie at my local building supply that worked nicely.
I also second JR's comment that the angle piece needs to be narrower than the brick being laid.
I also second Russel's comment about the pivot point of the IT being raised from the floor using a castor.. I also started with a modified castor thinking it was the coolest idea ever but switched to a hinge after realizing the issue with the vertical diameter being different from the horizontal diameter.
Here's my construction brace angle piece, my hinge pivot and the trimmed down angle piece to accommodate the narrower bricks at the top of the dome.

Also looking at one of your photo's I think you may be considering a full upright brick for your first course. I'm not experienced enough to advise on that but do some reading/searching in the forum on the first course.

Just throwing out some ideas. Good luck!

[JRPizza]

Two things come to mind looking at your pic's. You will need a narrower angle piece sometime during your build as the dome gets smaller in circumference and the bricks get narrower (if you decide to bevel and or avoid aligning vertical joints). It also looks like you may need to watch your angle bracket to make sure it does not loosen and fail to keep the bricks in proper orientation. Lots of us use metal for the angle which may hold up to abuse better than the wood you have chosen.

https://community.fornobravo.com/for...141#post381141

[danhem]

Yokosuka dweller and UtahBeehiver, points fully taken onboard and to my understanding of what you were saying have been implemented in our ITmk2 design.

It took a long time to get to this stage today so hoping the attached pics seem to make sense to you guys?