Nesting a group of 3v domes

[Cindi]

I am looking for someone who could create plans for this.  I found this on geo-dome.co.uk. http://geo-dome.co.uk/article.asp?uname=nest_dome

I am thinking I would want the central dome to be 40ft in diameter and the satellite domes 30 ft in diameter.  

I want to use EFTE Tefzal to cover the center dome.  What diameter would the pipes need to be to support it? The bottom row of triangles could be aircrete.  The satellite domes would also be aircrete, I could use the Tefzal for the pentagon on the top of these domes.  Any help would be appreciated. 

Cindi

[Levente Likhanecz]

Hi Cindi,

the dome arrangement at

 http://geo-dome.co.uk/article.asp?uname=nest_dome

looks like does not work with different diameter domes. their proposal seems to work with all dome same diameter.

the picture attached shows a 40foot and a 30foot dome connected by a corridor.

let wait somebody here figure out some solution for you.

cheers, lev

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[Cindi]

Thank you Lev,

I was thinking to connect the different sizes I could make a border inside the larger dome hexagon so the smaller dome hexagon could match up. Also if I use the Tefzal to connect them that should compensate for an necessary angles. 

[Ashok Mathur]

Dear Cindi

I am not able to locate right now, but some years ago, in this forum, there was an exchange on this topic lead primarily by Gerry of Qubec.

There is an excel sheet with solutions.

Regards

Ashok

Regards

Ashok

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[Levente Likhanecz]

lets have a look

https://3dwarehouse.sketchup.com/model/132dd177-6a95-4401-9021-6b03d7094f89/Cindi-3V-Kruschke 

well, it is not as you mentioned "hexagon in hexagon" reduction, but you can walk it aroun in the warehouse 

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[Cindi]

Lev, 

I think that would work with the Tefzal and bars mounted to the aircrete.  Would need something to keep it watertight though at the connections.  Thaniks!

Just need to see what size pipes would be best for a dome that size and the angle for the molds for the Aircrete triangles. 

On Saturday, April 25, 2020 at 3:13:35 AM UTC-4, Cindi wrote:

[Levente Likhanecz]

hi Cindi,

you wanna do the skirt from aircrete? like the pic attached?

how you wanna join those triangles, gluing or put some rebar in them and weld together? you mentioned you wanna make them prefabricated triangle by triangle poured into molds.

there are a lot of question. i'm not an architect (sadly to say), but they use to ask if it will be a living place or just a barn.

if you intend to build something like that for living in it there must be local regulations/approvals.

if you state those infos (your approx. location: country or state), purpose of use, might be some fellow here to give you a start what you can expect authorization-wise.

Ashok mentioned some work of "Gerry from Quebec" regarding nesting with excel calculators. Should try to locate them, to see the educated solutions.

cheers, lev

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[Ashok Mathur]

Let us keep part drawing tools Out of the way of thinking from mathematical tools which are ways of doing things.

As a way of thinking, imagine one 1v icosahedrons with pink five triangles at the top.

We have a horizon line. 

Slowly pull the pink top downwards till one of its edge is flush with the horizon line .

Take a second pink top icosahedron and also pull it down till Its pink top is also on the horizon line just opposite the previous pink set of five triangles. 

Now remove the pink triangles and join the two icosahedrons.

This is what we want to do despite the size and frequency complications. Match identical or near same shape openings.

Or start with a hexpent and pull its red hexagon down till it is flush with the horizon.

Repeat with the second hexpent till it is the mirror image of the first.

Join the two .

If the two domes are not mirror images there will have to be some sort of channel that will join the two different size openings.

Ashok

To view this discussion on the web visit https://groups.google.com/d/msgid/geodesichelp/CAOkvED%3Dqee22jSS5bpwE5QUDg-ormqgYHWO6w6GSpohSVrU2FQ%40mail.gmail.com.

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Regards

Ashok

[Levente Likhanecz]

hi Ashok,

i made an alternative connection between the 2 domes,

both regular 3V Kruschke 40/30 feet.

the green colored stuff is the modified part to connect them.

how it feels?

cheers, lev

To view this discussion on the web visit https://groups.google.com/d/msgid/geodesichelp/CAD-a3OgF8wXsHeyMDejx4iOJFZSqM7Px518ruzat5M6QyEQmZQ%40mail.gmail.com.

[Cindi]

Lev, 

The plan is to make 4 home domes out of aircrete, so for those the 30 ft domes, I need to know the angles of the sides so each triangle will fit together and support the ones around it. I am thinking 5" thick aicrete.  I have come accross some information where it is 5 to 7 degrees on the edges. Now since the bottom edges may not be flat I can make a ledge to accommodate the the different heights/angles. 

With the 40 ft dome, I think the same ledge would be the best, that way I have the clear view all the way around.  To attach the pipes to the ledge I can incorporate pipes in the aircrete as it sets up to mount the Tefzal triangles to. The ledge would be part of the foundation so there would be a solid connection there.  My plan is to have everything poured an drying for at least a month before construction to help with compressive strength of the aircrete.  The 40 ft dome will be a communal area.  Will probably live out of it while the rest of the triangles are curing.   If necessary the "ledge" the Tefzal sits on can by more concrete then aircrete for strength. 

I have been looking over some of the older discussions on this subject.  I see you recommended 3/4 to 1" galvanized pipe and stainless steel screws to hold it together.  So for a 40ft dome for safeties sake I should use the 1" dia pipe, correct?

Cindi

 

[Levente Likhanecz]

Dear Ashok,

if i catch good, your proposal to join to domes at the pentagon.

i made some plays (in mind a ca. 40feet main and a 30feet satellite dome)

my findings: to have the approximate proportions i made a 30feet 3V and a 40feet 4V standard dome. then i blew up the bigger a bit to have pentagon sides matching.

after setting them face to face at a pentagon a cut the balls to flat.

this method resulted class3 looking domes and only 1 satellite possible to connect. cause the other pentagons away from horizon.

regards, lev

On Mon, Apr 27, 2020 at 1:03 PM Ashok Mathur <ashokch...@gmail.com> wrote:

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[Levente Likhanecz]

hi Cindi,

the standard 3V dome does not sit flat (cut below or above equator) 

quote "bottom edges may not be flat"

the domes that sit flat without adjusting the foundation ledge called Kruschke dome. a 3V Kruschke has 4 different struts instead of 3.

but them sit good flat.

a quick check you can have a look at

http://www.domerama.com/calculators/3v-geodesic-dome-calculator/

i'm still in doubt how you want to join prefab aircrete triangles cause they have to push and pull each other so they have to transfer forces back and forth.

even with the smaller 30feet dome at 3V frequency you will have such large triangular slabs they will need reinforcement (rebars) to avoid braking under their own weight.

3v 4v 5v those numbers the higher then need more pipes but lesser individual lengths.

the 1 inch pipe story was about a 4V dome where the maximum length was about 6 feet only (ca 1.8 meter).

your plan of a 40feet 3V monster comes with  over 9 feet pipe length (ca 2.8 meter), and that is something.

hopefully some more people will join this discussion to have some professional advice.

cheers, lev

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[Cindi]

Ashok and Lev,

I found this in the warehouse: Geodesic Dome Cluster by TaffGoch,  He states they are all 3v, but it looks to me like the middle dome is a 4v?  That might help the matchup too.  I will have to look at them.  This will be built in Oregon this summer hopefully.  So it seems the pipes should be galvanized 1 in diameter. The pipes will only be for the middle dome, 

If I change the middle dome to a 6V then the triangles will be much smaller. I will be experimenting with the aircrete and the molds to see how it can work. The triangles that are smaller on the outside would fall out so there will need to be something to hold them in place until they set up. I think rebar or something similar should work. 

Maybe something like this: to connect the aircrete triangles.  This could work, you can nail and drive screws into aircrete.

 

On Saturday, April 25, 2020 at 3:13:35 AM UTC-4, Cindi wrote:

[Levente Likhanecz]

hi Cindi,

by the nature of these domes the "outside of the triangles" should come always bigger than the inner side.

like a simple arc's keystone.

my guess Taffgoch's cluster works due to all same diameter 3V domes (even the central piece), as he says over the description ( 11 feet radius all)

he truncated the satellites at 5/8 but the central piece plus 1 row more, that makes it look bigger, than the rest in spite of same dia.

to make central  6V  would trash the alignments.

download it, dissect it, measure it.

there can be some individual correction to lowest rows to sit flat.

probably you know already you need Sketchup Maker (which is freeware) to have a good study on the modell. 

that cluster looks excellent, as usual with Taffgoch.

cheers, lev

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[TaffGoch]

Cindi,

A couple of notes on my dome-cluster model:

1.)  Note that each dome is identical, regarding it's 3v tessellation, and size of pentagons and hexagons. The domes attach at a hexagon location, exactly, because the "shorter" domes are 4/9 profile, and the central dome is 5/9 profile. The hexagons are "regular," and the angle-of-intersection is a perfect match.

A photo of a geometrically-equivalent cardboad model is found in Domebook 2, which I SketchUp-modeled below:

2.) Note that I triangulated a transition "cap" to prevent snow/debris from collecting in the "valley" between domes, at the hexagon intersections. (Contractors call this a "cricket," and is typically used at the junction of a chimney and pitched roof.. Same reasons for use - no debris collection, and improved rain/snow runoff.)

-Taff

(aka, David Price)

[Levente Likhanecz]

hi Cindi,

i attached Taffgoch'es probable solution of the 3V cluster.

both domes 15 feet (4752mm) radius.

the yellows and the greens stretched a bit to sit flat on ground.

On Tue, Apr 28, 2020 at 12:09 AM Cindi <crit...@gmail.com> wrote:

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[Levente Likhanecz]

hi Taff,

thats a nice solution, just few minutes ago assembled it, i see that was a good assumption.

regards, lev

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[TaffGoch]

Cindi,

Preformed concrete geodesic domes aren't new:

 You can see details of how the edges are joined, with wire reinforcing-mesh overlaps that are concreted after panels are positioned. In this video, you can see the joining process:
https://www.youtube.com/watch?v=HHmbuKAEn34

Note that the concrete panels are formed on foam triangles, which makes them similar to insulated SIPS panels.

Also, note that once completed, you have a monolithic concrete shell, where struts don't matter. The video demonstrates that struts aren't used, and aren't really required. Once monolithic, the strength is in the shell, not the struts. (The video shows how, during assembly, the panels are supported without struts, using plenty of support-bracing during assembly.)

So, you CAN use struts, but they're not required.

-Taff

(aka, David Price)

[TaffGoch]

Cindi,

The concrete domes, depicted in my last post, are American Ingenuity domes (American Ingenuity, Inc., located in Rockledge, Florida)

If you can't access their webpage, keep trying. They have limited-bandwidth problems.

-Taff

(aka David Price)

[Ashok Mathur]

Monolithic dome is a well known dome company that uses thin shells to create domes. 

Of course they are not geodesic domes but are very strong structures.

They have thick ballon which forms the base of poured shell.

You could check with them if they work with aircrete.

Regards

Ashok

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Regards

Ashok

[TaffGoch]

I just learned that AI Domes is closed. The owner is deceased, and his wife is in poor health. The company is not producing any more product for shipment - only servicing locally-extant domes.

So, don't expect the website to revive. You can, however, see photos, desriptions and plans, collected to the WayBack Machine in early 2019:   WayBackMachine - aidomes.com

-Taff
(aka, David Price)

[Cindi]

Gentlemen,

Thank you for all of the info!  The aircrete will be similar then to the foam triangles with concrete.  Using the wire to tie the triangles together is awesome.  I know there won't be any struts.  I realize the bracing will be important as the domes go up.  If the outer edge of some of the triangles is wider then the inner edge that will support those triangles, it is the ones with the inner edges that are bigger that will benefit with the wire tie in.  I am going to be experimenting with the aircrete and a mini dome, I am more of a hands on kinda gal.  I don't really understand how to use sketch up, I should learn it, I know it would be easier and very helpful with my dome building.  I wonder if the 3V domes (30 ft diameter) were to touch each other all the way around, could go up to 5 domes around and then make a dome "roof" around the the domes, from the median of the exterior domes covering the middle like a cap, I could use the Tefzel. I have been reading about the pillow domes and that is what I want to do if possible.  Honestly you have helped me so much. I just need to come up with a design that I could bring to an architect for blueprints.   Attaching the Tefzel to the exterior dome roofs would reduce the foundation requirements and the Tefzel can be anchored to the domes. 

Thank you!

Cindi

[Cindi]

Taff,

I see that now and that is excellent.  I think now though I have a way to make it work without the need for the outer domes to match up.  Wherever they touch that would be continued on down the ground so as to provide an exterior wall to the Tefzel central dome cap.  Using the Tefzel I will have much more flexibility and should be able to anchor the Tefzel to the outer domes I want to attach it to the top mid-line point so as to allow run of to run off the exterior domes and not pool anywhere.

Cindi

[TaffGoch]

Cindi,

Take care with the foundation requirements. The Tefzel-covered domes at the Eden Project were evaluated, during design, and the foundations were found to be adequate for supporting the weight, BUT...

...were inadequate to hold the domes DOWN. Wind-tunnel testing showed that the domes needed to be "tied-down" with deeper foundations and more-secure attachments. The domes could not be built "resting" on the foundations - they had to be secured from lift. (Think airplane-wing lifting forces - Bernoulli's principle.)

-Taff

[Ashok Mathur]

Dear Cindi

A 3v dome has just three triangles whose angles do not change with increase in size.

Try this type of prototyping.

First print the required number of triangles on A4 sheets and paste the sheets on thick sheet from dollar store.

Make two domes with hexagons cut out as pointed by Taff.

Join with cello tape and see the problems.

Try to cut the triangles with styrofoam to simulate depth of aircrete.

Regards

Ashok

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Regards

Ashok

[lemondealc .]

Juan Sebastián has posted here about the aircrete dome he built. You should watch the video of it and learn from his experiment. Precision is key!

https://youtu.be/3JNGfGUi0-0  

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[Cindi]

Ashok, 

I actually made a 3v 3 ft diameter dome using 1 in styrofoam.  It turned out pretty good, only problems were the edges did not have the angle needed to fit completely and a few weren't cut perfectly.  There were no real gaps.  As long as I have the molds designed correctly and I start off with a circle to have the bottom pieces join properly I believe the dome will go together without too much of an issue.  I see from the Link Taff posted about the angle for the bottom triangle, That could be built into those triangles so there is no lift needed to start the correct dome angle.  I watched that one a few times and I am wondering if the fact he didn't have a circle to line up the bottom pieces help to contribute to the gaps he encountered.   If I have time before I leave to move to Oregon I plan on making a 3v 6ft aircrete dog house for a friend and so I can hopefully find what problems I may encounter when I build my domes in Oregon. I have foam board I made a 3v hexagon and pentagon that would be used in a 4 ft dome and they fit together very well.  

Again I need to be sure of the angle for the edges so there is no gap on the outer edge of the triangles.  The inner edge will fit together perfectly, it is the gap I need to be sure of.  From what I have found for a 3v dome I believe the angles will be 7 and 11degrees.  I found this on geo-dome.co.uk in the forums for domes without hubs: 

posted by    simon	27/08/2009 19:51:53
p12 For a 2v, bevel all the edges 11 degrees except for the long edge of the pent panels, and you bevel that one 7 degrees. For a 3v, bevel all the edges 7 degrees except for the long edge of the smaller triangle, and you bevel that 4 degrees. I think. Taff, I understand the need to properly secure the Tefzel film.  If I have it anchored across the top of all of the domes plus inbetween each dome have a pillar into the ground that a tether is attached it should be good. I will of course be discussing this with an architect before I start.  I need to get this drawn up in sketch up but I barely understand the program. I made a 3d hexagon but that is it. The info you guys have provided has been amazing, thank you!   Cindi

[Levente Likhanecz]

hi Cindi,

a last word about bevel angles.

you can do it without computer.

put a stick in the ground and attach a string to it. make a knot on the other and of the string at a distance like your proposed radius of your dome. (use non-stretching kind of string - maybe solid wire)

you move (and keep full stretched) the string then the knot will be radius distance from stick-point anywhere in the space around.

make your flat triangle - the base of your mold - (chord lengths given) and set it in place that all 3 corner (vertices) at knot length. then the bevel angles shown by the stretched string touching around the sides of the triangle.

cheers, lev

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[Levente Likhanecz]

hi Cindi,

i uploaded to 3d warehouse the 6V version of Taff's design.

https://3dwarehouse.sketchup.com/model/f8892e85-b402-4801-af06-62333f844277/6V-cluster-40-feet-diameter

just in case

cheers, lev

On Thu, Apr 30, 2020 at 7:34 PM Cindi <crit...@gmail.com> wrote:

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