Dome spreadsheet calculator

[Rocko Bonaparte]

Big qualifier is that the spreadsheet assumes that the builder is using a fixed length IT. You want to change the length during the build, I am not able to deal with that one.

Are you super duper sure?

I had a notion of trying to flatten the height of the dome as I went up instead of going perfectly semi-circular. I was figuring in whatever math I was about to do that it would be a linear interpolation going from the dome radius up to the final height the closer I got to that final height. I haven't studied your calculations enough yet for me to dive in either, and it's likely I'll just throw up my arms and go semi-circular too.

[autumncs]

Side angle is determined based on the number of bricks on the course. formula is 360 degrees/#bricks/2 = side angle (where the # of bricks is the count for a full circumference). So if you have 36 bricks, then the side angle is 5 degrees on each side. As you go up, the number of bricks per course will drop w/ the circumference (meaning the angle gets more acute) - and then, at some point everyone starts cutting them into thirds because they're too hard to work with - at which time the brick count goes up again. Make sense?

By the way - the spreadsheet will calculate the number of bricks needed and the side angle based on the width of the brick you tell it you are using. Think it is the far right column where you enter that, IIRC

Thanks, I think I understand. I'm building a smaller oven (32") so it doesn't go over 9 coarse's. I can't remember but I do remember reading somewhere that the larger ovens this will change more.

Below are the calculations, I've added metric measurements in for myself.

[deejayoh]

Hey deejayoh I have a question about the jig degree's. I haven't started the cutting yet and getting my head around jigs etc. I'm looking at using mrchipster jig however this isn't about the jig as such but the side angle. As you see below it ranges from 5.7 to 6.4 per coarse. I take it this is the static angle as mention in mrchipster's jig and if I set that to 6 I should be good?

Side angle is determined based on the number of bricks on the course. formula is 360 degrees/#bricks/2 = side angle (where the # of bricks is the count for a full circumference). So if you have 36 bricks, then the side angle is 5 degrees on each side. As you go up, the number of bricks per course will drop w/ the circumference (meaning the angle gets more acute) - and then, at some point everyone starts cutting them into thirds because they're too hard to work with - at which time the brick count goes up again. Make sense?

By the way - the spreadsheet will calculate the number of bricks needed and the side angle based on the width of the brick you tell it you are using. Think it is the far right column where you enter that, IIRC

[autumncs]

Hey deejayoh I have a question about the jig degree's. I haven't started the cutting yet and getting my head around jigs etc. I'm looking at using mrchipster jig however this isn't about the jig as such but the side angle. As you see below it ranges from 5.7 to 6.4 per coarse. I take it this is the static angle as mention in mrchipster's jig and if I set that to 6 I should be good?

[deejayoh]

I have a v4 spread sheet and don't see column R. I tried to select Q and S then unhide, but no luck. Maybe you could post a V5 and put your graphic back in too

Sorry, should be column "S". I pulled earlier version. The google doc version is correct and it has the graphic in it. I think I will update the post to make that the primary "go to" version

https://docs.google.com/spreadsheets...it?usp=sharing

[JRPizza]

I have a v4 spread sheet and don't see column R. I tried to select Q and S then unhide, but no luck. Maybe you could post a V5 and put your graphic back in too

[deejayoh]

Dennis, I had a question for you. The spread sheet has pretty much constant brick "width" (give or take a half an inch) if I am reading it right, but if you make the bottom width of a brick the same width as the top of the brick below (or a multiple of the width as you get near the top) you can make a dome with all the vertical joints perfectly centered on the bricks below and not need to use any custom cuts till you tie into the arch, which usually needs custom cuts anyway. That is what I did after I noticed lots of other builders had their bricks get smaller near the top. Was your intent to recommend constant width bricks for the whole dome? I will say that I had a crack that went through a few bricks, so I am not sure how much staggering the joints really got me.

No, check column R in the spreadsheet. It's an input column and you can adjust the width of each brick for every course. I used half or third width bricks at the top. Ideally, I guess you'd want to adjust so that you have the same number of bricks on each course (which allows you to offset/stagger each) but in practice that is a lot of cutting! I went with whole bricks as long as I could - then when the side angles got too extreme I started to reduce the width.

[JRPizza]

Dennis, I had a question for you. The spread sheet has pretty much constant brick "width" (give or take a half an inch) if I am reading it right, but if you make the bottom width of a brick the same width as the top of the brick below (or a multiple of the width as you get near the top) you can make a dome with all the vertical joints perfectly centered on the bricks below and not need to use any custom cuts till you tie into the arch, which usually needs custom cuts anyway. That is what I did after I noticed lots of other builders had their bricks get smaller near the top. Was your intent to recommend constant width bricks for the whole dome? I will say that I had a crack that went through a few bricks, so I am not sure how much staggering the joints really got me.

[deejayoh]

Deejayoh,

Struggling a little bit with relating the headers on your spread sheet to the 'bevel/angle/taper' definitions....

This will probably come clearer to me once I get a saw/start building - but a little assistance now would be super...

TIA!

Sorry for the slow response. I was on a pizza pilgrimage in Italy for the last two weeks

I guess I'd need you to define Bevel/angle/taper before I could be sure I was replying accurately - but this graphic is supposed to be in the spreadsheet (not sure what happened there) and might help clarify. You only need to know the two measures. The third one will be determined by the jig (relevant articles are linked in the first post)

Dennis

[fnbroken]

Deejayoh,

Struggling a little bit with relating the headers on your spread sheet to the 'bevel/angle/taper' definitions....

This will probably come clearer to me once I get a saw/start building - but a little assistance now would be super...

TIA!

[RandyJ]

Yes I have the HF saw. Mine is like 3 or 4 years old so I do not know how it compares to what is out now. Yes it cam do most of the compound angles without a problem. I did start out doing both angles and bevels but is you are just slightly off you will run in to problems with things not fitting like you want . That is why I would not even consider doing both again. I do like the tight look on the inside of the dome and you will never see the outside after you are done. Also I have about 1\2 " of extra mortar as cladding. I did not want the mortar going to waste so as it hot stiff I just smeared it on the outside of the oven.

[Yeager]

If I was going to do mine again I would just do the bevels and leave the bricks square. It is a lot easier that way and it will make no difference in the end product.

Randy

Thanks Randy! If I remember right, you used the HF tub saw also. Do you think it could have done a compound cut rather than make a jig? I am still scratching my head as to why a jig would be needed on a HF tub saw if you wanted to do dual angles with one pass?

[Texas]

Here are the measurements we used for a 36" oven. http://www.fornobravo.com/community/...w-area?t=21562 look at posts #9, #10, #11.

http://www.fornobravo.com/community/...-forms?t=21566 - post #5 shows the jig we used to get the angles determined in the spreadsheet I used that is in the posts indicated above. Worked for a 36" oven. In theory, can enter your diameter and other specs, and it should work for other diameters. I used the measurements more than the angles..... inside top, inside bottom, outside top, outside bottom and we cut as close to those as possible. Once the jig was set up, we cut almost the entire level of bricks.

Good Luck with your build..... here are the notes from our 36" http://www.fornobravo.com/community/...lding-the-oven

[RandyJ]

If I was going to do mine again I would just do the bevels and leave the bricks square. It is a lot easier that way and it will make no difference in the end product.

Randy

[Yeager]

I just bought a new Harbor Freight 10" Tub saw. It has a bevel adjustment and miter allowing for a compound cut. Is there a reason to make a jig vs just use the bevel/miter in a single cut on the saw? Which angles on the spreadsheet would you use?