Dome spreadsheet calculator

[dakzaag]

I have to hand it to you math wizards, I cannot wrap my mind around being able to calculate all the numbers and furthermore having a jig accurate enough to split degrees in half. I have built at least a dozen ovens in the last three years and while they all work out fine, I have a fair number of cuts that just aren't right and end up in an ever increasing discard pile (which would make someone a decent oven if they had the patience to piece it together...) Eventually I am sure I will get a build where the cuts are good enough to eliminate the mistakes, but I certainly could not cut every brick and then expect it to fit together just like on paper. I love the energy and thought this exercise takes and collaboration between contributors.

[deejayoh]

I had to re-learn trigonometry to put together the spreadsheet. I just figured there should be one, and there wasn't!

[patjer1]

Hello,
I downloaded the spreadsheet and made some adjustements so it calculates in mm. Is it possible that when is take a 1000mm dome = 39.40" that the last row exists of 7 bricks with an outside bottem measurement of almost the same as a whole brick (4"), just as the 12 courses before? I thought that when you go up in the dome the bricks are no more then 1.5 or 1", they just get more narrow, or am I completely missing something?

Friendly greetings from Belgium!

I read the posts again carefully and now I understand it, you can define the width by yourself in column S

[ML38]

Dennis,

You are probably getting tired of answering questions 5 years later but I'd like to bounce what I did off you and the result to see if it sounds right?

I liked the idea of reducing the size of the brick from course to course the the joints are staggered so I used Column R to calculate the inside top dimension and then used that as the outside bottom of the next course. When I did this, the Side angle dropped so that it starts at 0.1 for course 1 and gradually increases until it reaches 4.9 on course 11.

Does this sound right? By using 4.9 for all the courses except for the first couple which are 5.5 (this really confuses me because the side angle increasing as you go up makes sense to me) are you just saving yourself some adjustments as you go?

The other confusing equation you have is for brick count of each course. You use the Outer Radius when isn't it the Inner Radius driving the brick count considering the inner is where the bracks are edge to edge plus joint thickness.

I may be missing something so please correct me if I did. Below is the screen capture showing what my side angle and inner and outer brick widths would be
Thanks

Marc

[Rocko Bonaparte]

If you know what your angle is for each course - you could tweak the spreadsheet with the right variables to have it calculate the angles and brick counts. It's just not set up to do that automatically. I figure if people want to get fancy, they'll do the math

I glanced at the spreadsheet the other day, and it looks like it wants the height of the brick at the inside of the oven. So on a technicality, I could monkey with that number.

Right now, I'm dabbling with tapering the bricks. I can set up a saw in a cool spot and queue up some bricks over a week to lay out in Hot Summer Mosquito Death Zone™ in the early evenings. If I keep it spherical, it would be the same angle each time. So if the brick height is based on the inner height, then I could just enter that in.

Do I have the right idea here?

[Rocko Bonaparte]

For the jig setup, is the difference between the current and previous tilt angles the angle I use on my cutting jig to get the appropriate bevel?

[deejayoh]

For the jig setup, is the difference between the current and previous tilt angles the angle I use on my cutting jig to get the appropriate bevel?

the tilt that's in the model is the total tilt, if i'm understanding the question correctly

[andrewe]

I'm wondering if there's a way to incorporate a radius taper (for low vault style ovens)? Anyone know how this can be achieved? Thanks!

[deejayoh]

I'm wondering if there's a way to incorporate a radius taper (for low vault style ovens)? Anyone know how this can be achieved? Thanks!

If you know the shape of the arc you want for the side profile, you should be able do this by adjusting the radius and height of each course in columns H and J

[andrewe]

If you know the shape of the arc you want for the side profile, you should be able do this by adjusting the radius and height of each course in columns H and J

Thanks, that's actually very obvious, I can't believe I didn't think of it. Great spreadsheet btw, thanks a ton!

[andrewe]

If you know the shape of the arc you want for the side profile, you should be able do this by adjusting the radius and height of each course in columns H and J

Sorry for another reply, I just got out of school and I'm restarting where I left off.

Will adjusting the radius and height of each course affect the jig calculations (will they be off) ?

Probably the best solution for me would be to be able to have a secondary radius option (the height from floor to ceiling) and use that as the second radius in an ellipse to calculate everything. I am still not sure how every calculation works in the sheet. If you have any ideas about how this would be implemented, I'd love to hear your suggestions!

[andrewe]

Sorry for another reply, I just got out of school and I'm restarting where I left off.

Will adjusting the radius and height of each course affect the jig calculations (will they be off) ?

Probably the best solution for me would be to be able to have a secondary radius option (the height from floor to ceiling) and use that as the second radius in an ellipse to calculate everything. I am still not sure how every calculation works in the sheet. If you have any ideas about how this would be implemented, I'd love to hear your suggestions!

An update to this. I created my own program to calculate the tilt cuts on each course for a non spherical dome (elliptical). If anyone is interested let me know. Basically the program gives me a read out of the angles I need to cut and a preview of what the curve should look like. Something like the photo I attached.

[daniel679]

The figures for the rough number of bricks to buy is slightly confusing. I'm getting 133 for the dome and 25 for the floor (wide edge) for a 36" oven with 2.5x4.5x4.5 bricks. The 25 figure explicitly states "Assumes exposed face dimension of 4.5 x 9.0 inches" which means twice the size of the brick dimensions entered, which confuses me. Does that mean I need 133 bricks with the size 2.5x4.5x4.5 and 25 bricks with the size 2.5x4.5x9? Or 158 bricks 2.5x4.5x4.5? Or something else altogether?

If someone could share an estimate for how many bricks are required (and what size) for the arch+front part of a 36" oven, that would be very helpful.

Thanks! This forum and spreadsheet are very helpful.

[GreenViews]

An update to this. I created my own program to calculate the tilt cuts on each course for a non spherical dome (elliptical). If anyone is interested let me know. Basically the program gives me a read out of the angles I need to cut and a preview of what the curve should look like. Something like the photo I attached.

Hi, Andrewe, I would be very interested in your program for these cuts. I am half way done with the build for the base under my oven and working on designing my actual oven. Thanks, Tom

[UtahBeehiver]

Deejayho did a nice calculator in excel. Attached is zip file

Pompeii_dome_calculator_v4.zip