32" build in Calgary, AB - pompeii neapolitan

[IH123]

It is useful to have some adjustment because removing it can easily break the mortar bond with the brick tight up against the bracket of the IT. Some builders use some corrugated cardboard there which can slide out with a bit of give to help removal without disturbing the brick mortar bond. You’ll work out a method as you go.

never thought of this before however 100% valid as brick surface is flat. my trammel however has a screw bolt that when unscrewed from its tight it will have few mm play to allow easy sliding away, the quarter circle tool is even better as its only 1/4" thick.

lucky me I am aiming for 1/8" max mortar so that would help is tiny soft tapping should fix the consolidation too.

[david s]

Thanks, I will try not to use it for the dome though

It is useful to have some adjustment because removing it can easily break the mortar bond with the brick tight up against the bracket of the IT. Some builders use some corrugated cardboard there which can slide out with a bit of give to help removal without disturbing the brick mortar bond. You’ll work out a method as you go.

[IH123]

A turnbuckle makes a great adjuster.

Thanks, I will try not to use it for the dome though

[IH123]

If you have the ability to make the IT length adjustable (small increments) it will really aid you when doing the brick work. There are so many variables that can make the course laying wonky, ie mortar gap creep, brick size variations, etc. By having an adjustable length IT you can correct the variations as they come up.

I will try to dry fit first, I am not sure why do I need to adjust the radius when its a fixed. I have seen others on the forums here use it to draw the arch cuts , however for the dome with fixed radius I am thinking, I should stick to fixed tool, the dome won't be stable if some of the bricks are not on the exact sphere, so I think if I build a brick out of order I have to replace it.

[IH123]

I have created the insulation board cuts plan, the best I can think of:

[IH123]

so here is the quarter circle that i made, yet to cut at the bottom 16 1/8- 141/8=2.00", I will however do that closer to when the dome spring line/soldier course and hearth is built so I can adjust the amount based on if the hearth is at same level as soldier course or not. the picture below shows the oven foot print template (to be used to cut insulation) and the dome curve check tool (quarter circle):

[david s]

A turnbuckle makes a great adjuster.

[UtahBeehiver]

If you have the ability to make the IT length adjustable (small increments) it will really aid you when doing the brick work. There are so many variables that can make the course laying wonky, ie mortar gap creep, brick size variations, etc. By having an adjustable length IT you can correct the variations as they come up.

[IH123]

If you can get your pivot point lowered to match the top of the brick floor it will give you the "most" hemispherical dome. I am not sure you would ever notice if it was higher in the middle by an inch or more but if you can place it optimally without too much trouble, why not? I used a technique I picked up from Gulf I call the "wooden brick" that put my pivot point at a height that made my oven half as high as it's diameter.

Thats what I was thinking of doing, I am also making another tool: attached an axle (stick) on two quarter circles glued together side by side (to become thicker as I used 1/8" thick board to get precise cut) and I could insert the stick of them into the centre of the oven (into a drilled hole on hearth brick ( to be replaced by wood brick if cant drill - thanks for the tip),which later I could seal with refractory mortar as its a tiny pin size hole on hearth brick, with this tool the quarter circle rests on actual hearth, I only need to cut from the bottom of the quarter circle board the thickness(height) equivalent to the distance between hearth top surface and actual sphere /dome centre below it , which is in my case about 2" below the hearth -I will post pictures tomorrow when I finish it its being kept clamped to curing the wood glue now.

I will actually cut the quarter circle board bottom AFTER building the dome's spring/soldier line and hearth, thats because levelling under hearth or dome first course my not be exactly at same level when built and not known exactly now, by then , I can measure the distance between dome's first course brick's bottom and the hearth brick top surface and cut the board as needed so it creates my dome desired height of 14 1/8"

[IH123]

This exchange reminded me of a post I made about a year ago...

This is when I like to remind new builders of the wealth of information on the Forum. All builds are unique, but there are certain "rules" and techniques that pertain to most of the projects. A little time spent researching a topic can pay dividends down the road by saving both time and money. Members are more than willing to provide answers to direct questions and will offer suggestions if they notice something, but that depends on the right person being on line when you need help. This aspect of a community site is invaluable, but there are ways to exploit the already available information and focus your questions.

If you're new to the Forum, it's not practical to read hundreds/thousands of posts, but you need to read some to understand the lingo. Once you do, don't underestimate the power of searching the Forum for a particular topic. Granted, sometimes using the built in search function can be challenging, but it can yield good info.

Another option that works well is a direct web search. If you type the url site:community.fornobravo.com "indispensable tool" or whatever term you need in your web browser, you may get better results. Now, as with any search, the results depend on the people adding the content. In this case, you would miss posts with the misspelling indispensible. Also, the results of one search will lead you to search more focused topics.

IH123 Thanks for indulging me this public service announcement on your thread.

Looking forward to following your progress!

Thanks for the tip, I have looked through many forum posts however sometimes when someone is undetermined and choose a thing under the pressure of time and design complexity it helps a lot to hear from someone else

[JRPizza]

If you can get your pivot point lowered to match the top of the brick floor it will give you the "most" hemispherical dome. I am not sure you would ever notice if it was higher in the middle by an inch or more but if you can place it optimally without too much trouble, why not? I used a technique I picked up from Gulf I call the "wooden brick" that put my pivot point at a height that made my oven half as high as it's diameter.

[Giovanni Rossi]

This exchange reminded me of a post I made about a year ago...

This is when I like to remind new builders of the wealth of information on the Forum. All builds are unique, but there are certain "rules" and techniques that pertain to most of the projects. A little time spent researching a topic can pay dividends down the road by saving both time and money. Members are more than willing to provide answers to direct questions and will offer suggestions if they notice something, but that depends on the right person being on line when you need help. This aspect of a community site is invaluable, but there are ways to exploit the already available information and focus your questions.

If you're new to the Forum, it's not practical to read hundreds/thousands of posts, but you need to read some to understand the lingo. Once you do, don't underestimate the power of searching the Forum for a particular topic. Granted, sometimes using the built in search function can be challenging, but it can yield good info.

Another option that works well is a direct web search. If you type the url site:community.fornobravo.com "indispensable tool" or whatever term you need in your web browser, you may get better results. Now, as with any search, the results depend on the people adding the content. In this case, you would miss posts with the misspelling indispensible. Also, the results of one search will lead you to search more focused topics.

IH123 Thanks for indulging me this public service announcement on your thread.

Looking forward to following your progress!

[IH123]

FYI, The vertical ID will be larger than the horizontal ID by the thickness of the plywood and the lazy susan bracket thickness unless you make incremental adjustments as you move up in courses. Also the centerline of the pivot point at the floor elevation to the bracket holding the brick needs to be at center of the brick face or you get a stepping of the bricks that are cumulative as you go up.

Thanks for the observation, I eyeballed and used a ruler to ensure the vertical and horizontal axis (the bolt vs centre of lady Suzan bearing) are intersecting in the centre and the line on arm I used as reference to be the radius of the actual centre is shown in the below picture:







I plan to put the base of this trammel above insulation, not on hearth, so the actual centre matches the desired position of the dome centre. There are of course errors everywhere however I try to minimize all I can. its not going to be perfect circle mathematically but very close, and I will use the wood quarter circle as the main reference. I will have to dig in the insulation 1/4" for my trammel to work (or leave a chunk of insulation out and pad it with wood sheets to level ( after finishing I put the insulation and hearth brick cut back).

does lowering the trammel to below the hearth fixes the issue you mentioned about stepped vertical circle?

[UtahBeehiver]

FYI, The vertical ID will be larger than the horizontal ID by the thickness of the plywood and the lazy susan bracket thickness unless you make incremental adjustments as you move up in courses. Also the centerline of the pivot point at the floor elevation to the bracket holding the brick needs to be at center of the brick face or you get a stepping of the bricks that are cumulative as you go up.

[IH123]

I today made the indispensable tool , unlike most of DIY design you see using caster wheel, I used lazy Suzan bearing instead. I found that the caster wheel has its vertical axis and horizontal axis do not intersect leading to a torus/doughnut outcome not sphere. I did use a back arm to fix the caster wheel axis issue but the problem it was too high for my low dome sphere and found that lazy Suzan bearing will provide the best of everything: very thin, no need for back arm and then trammel arm (double the inaccuracy and joints lots of play), the axis can be made to intersect leading to a perfect sphere output. I also created a quarter circle from 1/2" plywood(not shown in pictures) made with my dome's radius to double check the curve. my dome radius is supposed to be 16 1/8" . I repeatedly measured the actual radius (while trammel is at 0 degrees) and it is 16 1/8' exact. Here are the pictures :