New Nexorade/Rotegrity project

[TaffGoch]

I've been playing with new nexorade geometry that is not too complex, but just a bit more intricate than previous rotegrities that I've modeled. I started with a Class-III, frequency 3v{2,1) tessellation, produced the dual, then slightly rotated the edges (or "nexors" in nexorade parlance):

It took some fine-tuning to get the equal-thirds nexor subdivision, but the initial nexor rotation got me pretty close. For those new to nexorades, the above animation depicts the general theory of how nexorades are produced.  The "rods" in the depiction can be substituted with planks, "springs" or straps:

Note above, that the nexors can be rotated (about their midpoints) in either, a clockwise, or counter-clockwise direction. Conveniently, the nexor definitions (third-subdivisions) do not change. Either sphere can be constructed, using the same nexors. There are, by the way, four different-length nexors, totaling 210 count. I'm currently considering constructing a snug-fitting strap "cage" for a large beachball...

...maybe putting a bright LED light source in the center, for backyard "moon" ball lighting (suspended overhead, between two trees.)

-Taff 

[TaffGoch]

By the way, if you want a larger version of the second (straps) image to study, you can find it here:

http://taffgoch.deviantart.com/art/Nexorade-3v-2-1-615949183

-Taff

[TaffGoch]

These are the nexor variations that I mentioned:

Straps

Rods

Planks

Springs

Simplified depiction of the basic geometry of the nexor "thirds" arc-subdivisions:

-Taff

[TaffGoch]

On Friday, July 1, 2016 at 8:21 PM, Robert Clark wrote:

Beautiful nexorade.  Maybe you can cover it with heat-shrink boat plastic.  Do you know if it is possible to have just one or two lengths of nexors?

_________________________

Robert,

Three of the nexors are pretty-darn close to being the same length. The pentagon nexors are noticeably shorter. In physical construction, it may not affect the spherical shape too much, if only two definitions are used. Only physical experimentation will tell....

-Taff

[TaffGoch]

Robert,

Nexor comparison:

-Taff

[TaffGoch]

Robert,

"...that's not really much to look at..." -- unless you know what you're looking at! 

I found it to be a good physical representation of what could have been iteratively-calculated in a spreadsheet. Excellent depiction, actually. 

-Taff

[TaffGoch]

I just noticed that one of the examples from Clinton's "Equal Central Angle Conjecture" paper is a 3v{1,2} dual,...

 which should be good initial geometry for rotating nexors(edges,) to produce this particular nexorade.

Perhaps equal nexor length is, indeed, practical -- will give it a try.  (Although, equal-third subdivision may not behave. It might be possible to meet one criteria, but not both.)

-Taff

[TaffGoch]

Initial test of hypothesis doesn't bode well....

It is, nevertheless, a good starting-point for fine-tuning, but since I've already tuned the original, to achieve "thirds" with varying-length nexors, pursuing this (above) 3D exercise would end-up producing the same results. 

-Taff

[TaffGoch]

Regarding the original nexorade post:

These chord factors will produce a sphere of unit (1.000) radius. Straps are depicted, but values are valid for each of the previously-depicted nexorades. (For color-coding, refer to the "rod" or "spring" depictions.)

-Taff

[TaffGoch]

Color map of nexor chords...

...should you find such more convenient than prior depictions.

-Taff

[TaffGoch]

I've posted the SketchUp model to the 3D Warehouse:
https://3dwarehouse.sketchup.com/model.html?id=5b5a1809-5e01-496b-b03d-060c82a72494

-Taff
(File attached, as well.)

[TaffGoch]

Had a thought, last night...

...could the same straps be used to assemble a "little brother" to the original nexorade?

Seems so! Just connect strap endpoints to the "other" mid-points.

-Taff

[muhammad karim Toury]

Hi

I made up a rotegrity sphere by aluminium tube  (8 mm in diameter) and joints were by means of wires. Joint holes on every element are linear and they are not at the right angle (photos attached). Now I want to make up a bigger one and join them by bolts and I need the right angles in order to drill the elements. I need help to find the angles.  

[muhammad karim Toury]

[TaffGoch]

Hang in there, Muhammad, I'm working on it!

I've done what you are proposing (bolt connectors,) and can relate that the resulting appearance is gratifying. I'm planning another construction, but with hidden pins, so that no connectors are visible, at all. You're correct that the proper angles and hole positions are critical.

I've completed the model, and will work on the bolt centerlines, next.

What diameter rod are you considering for your large project? I can model to conform to that diameter, and produce hole spacing diagrams for each of the two different-length rods (yellow, green.)

-Taff

[muhammad karim Toury]

Thank you so much Sir for your attention and patience.

I want to make a rotegrity sphere by tube 80 mm in diameter to gain sphere 4m diameter.

Thank you 

Muhammad Karim

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[muhammad karim Toury]

I want to now the difference of these two arrangement in rotegrities that I attached.

thanks

[muhammad karim Toury]

Hi

I built a 5-nexor fan to explicit the drilling angles by the real model but the bolts are so serious about little faults. I couldn't do that right. I want to examine it by smaller bolts into bigger holes.

On Sat, Dec 10, 2016 at 7:19 AM, TaffGoch <taff...@gmail.com> wrote:

--

[muhammad karim Toury]

I do it by smaller bolts and could complete the mission.

Tubes are 970 mm length and c/c of holes is 270 mm, holes are 20 mm in diameter and 4 bolts are 20 mm and 2 of them are 8 mm. 

[TaffGoch]

Muhammad,

I paused working on the hole angles, to answer your other question:

Here's the comparison:

The rotegrity "straps" (of the same color) are the same length/width (but bent to different radii, of course, producing different-size spheres.)

In 3D-modeling, I refer to the two different size rotegrities as "greater" and "lesser," to keep my model files organized. Technically, they are, both, Class-II, 2v rotegrities.

-Taff

[muhammad karim Toury]

Thank you Taff,

I will call them Greater and Smaller,

is there a special relation between radii of two sphere (that are made from same straps but in different arrangement) ?

Attached my today job.

Muhammad Karim

--

[TaffGoch]

The ratio of sphere radii is about 1:¾

It varies, somewhat, for different tessellations. For example, this greater/lesser rotegrity pair...

...has a slightly different ratio -- still approximating 1:¾

-Taff

[TaffGoch]

Muhammad,

80mm diameter tubing will produce a nexorade diameter of 4.44 meters.

If this is in keeping with your proposal, I will scale the model, using 80mmØ tube dimension as the basis. I will then be able to provide precise measurements between holes, along the length of the two tube definitions.

(I've completed the hole centerline angle derivations.)

-Taff

[muhammad karim Toury]

Thanks a lot Taff

Is there any geometrical formula for these rotegrities ?

--

[muhammad karim Toury]

Good job !!!

This is exactly what I want.

--

[TaffGoch]

Muhammad,

Here is a reference/guide image of the nexorade:

The wedge shapes depict the plane of the strut, extrapolated from the sphere center. The wedge is used to define the zero-angle (centerline) alignment of the strut.

The angular-deviation of each bolt-hole is measured from the plane of the wedge.

Pent strut:

Hex strut:

NOTE: While the hex strut (green) CAN be flipped end-over-end,...

... the pent strut (yellow) CAN NOT! I have color-coded the end of the yellow strut, to depict which end is connected to the green strut. If you examine the top-most nexorade reference image, you will note that one end of the yellow strut is green, while the other end is yellow. (The green strut ends are both yellow.)

The metric-length dimensions are based on a strut diameter of 80 millimeters.

-Taff

[TaffGoch]

There are many articles, about nexorade derivation and mathematics, in this Geodesic Help Group topic:

https://groups.google.com/forum/#!topic/geodesichelp/vrDkGnHlX-Y

Fun reads!

-Taff

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[TaffGoch]

Muhammad,

Be forewarned:  The 3D-model that I produced is VERY tight! You will likely need mechanical "assistance" to pull parts into alignment, so that bolt-holes line-up. A small model should be easy, but your full-size project will be challenging (to say the least.)

Don't worry, even Kenneth Snelson uses a "come-along" to assemble his large-scale projects.
https://www.google.com/search?as_epq=Kenneth+Snelson

-Taff

[muhammad karim Toury]

Thanks a lot, Taff,

Everything is clear,

121 mm end of yellow struts will rest on greens. Am I right ?

And because both ends of greens rest on yellows we can flip them end-over-end.

--

[TaffGoch]

Muhammad,

"...​121 mm end of yellow struts will rest on greens. Am I right ?

And because both ends of greens rest on yellows we can flip them end-over-end."

Your understanding of yellow/green strut orientation is correct

-Taff

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[muhammad karim Toury]

I extracted rotegrity sphere from 7v geodesic dome by AutoCAD.

[muhammad karim Toury]

Taff,

I have some questions about rotegrity geometry,

You sent me the lengths and angles of elements for a rotegrity in "greater" arrangement, can I make "lesser" type by means of these elements? Briefly I want to know that is the geometry of greater and lesser different or same?

Second question

In the dimensions that you sent me why the two ends of yellow strips are different? (108 and 121 mm, because these lengths are not affective on the form geometry) while these lengths are equal in greens.

Muhammad Karim

[Ashok Mathur]

Dear Karim,

Pl explore this book

[PDF]RECIPROCAL FRAME ARCHITECTURE

https://casaeco.files.wordpress.com/2012/03/reciprocal-frame-architecture.pdf

The title of this book, Reciprocal Frame Architecture, asserts that this is a book about ...... structures as 'nexorades', the name coming from the Latin word 'nexor',.

See if you like it.

Regards

Ashok

Regards

Ashok

[muhammad karim Toury]

Dear Ashuk

I had read this book,

and I couldn't to find my answers,

There isn't any information about rotegrity.

regards

Muhammad karim

[TaffGoch]

Muhammad,

"You sent me the lengths and angles of elements for a rotegrity in 'greater' arrangement..."

I have not provided you any rotegrity measurements or angles. I don't understand your queries.
___________________________

"In the dimensions that you sent me why the two ends of yellow strips are different? (108 and 121 mm, because these lengths are not affective on the form geometry) while these lengths are equal in greens."

Only the central 3 dimensions, of each nexor, are critical. You can make the end dimension any length you wish.

(I was "eyeballing" the end lengths, to relate to overhang. Since the angles between nexors are different on each end of a yellow nexor, I extended the end length at one end to provide roughly the same overhang.)
___________________________

Sorry for the delay in replying -- I've been in hospital.

-Taff

[muhammad karim Toury]

Taff,

I hope you will have good feeling.

"You sent me the lengths and angles of elements for a rotegrity in 'greater' arrangement..."

I have not provided you any rotegrity measurements or angles. I don't understand your queries.

You said me that you call the different geometries lesser and greater,

Anyway, I bought plastic tubes to make a model in real scale and check the precision that I need before cut and drill the metals.

Muhammad

--

[TaffGoch]

I commented on the greater and lesser rotegrities, as employing the same "bands" or "straps," but never provided any angles or measurements. That's why I can't quite follow your questions.

Might you be referring to the nexorade (not the two rotegrities)?

-Taff

[muhammad karim Toury]

Hi Taff,

We made a big scale rotegrity dome,

Thank you for your helps,

Your helps were so useful and practical,

I want to send you some photographs and I will describe more in future.

Best Regards

Muhammad

--

[TaffGoch]

Oh, yes, indeed -- more details, please.

I'd like to know, in particular, how well the bolt-hole alignment performed for you.

Where can this art project be seen? Is it permanent/semi-permanent display at a gallery? At an art exposition?

"Readers want to know."
______________________________

Thanks for the photos. It looks impressive. I hope you received many comments/compliments.

-Taff

[TaffGoch]

At Tabriz Art University?

Was this project, in part, pursuant to completion of your degree?

-Taff

[muhammad karim Toury]

It is a 4.40 m diameter sphere by means of tube that D=76 mm and t=3mm,

Diameter of holes are 18mm and because of less accuracy at drilling, we had to use 14mm bolts,

We made this for a workshop for Master students of Islamic Art University of Tabriz and shown for a day at a congress at Shahid Beheshti University of Tehran,

now this is dismantled.

Muhammad Karim Toury

--

[AzaFran]

That's it, guys! More details please about align bolts-holes really interesting. I'm also studying to make a model and later a bigger structure learning about rotregrity. Thanks for share and keep'n good work.
Looks really nice,
Regards,
Taji

~~~~~~~~~~~~~~~~~
                D.A.L.E!
Despertando a la Ekosofía
~~~~~~~~~~~~~~~~~

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[TaffGoch]

"...and shown for a day at a congress at Shahid Beheshti University of Tehran,
now this is dismantled."

That's just wrong! It surely deserves more exposure than one day. Hopefully, you can find another venue.
_________________

(Thanks for the additional photos.)

-Taff

[Dick Fischbeck]

true. 1 day??

[TaffGoch]

For anyone that may be interested, I've posted the SketchUp 3D model, to the 3D Warehouse:
Nexorade • 2v{1,1} • 3D Warehouse

-Taff

[TaffGoch]

Serendipity! I have, just now, stumbled across this 4v nexorade dome, in Spain:

Webpages: http://lucesdebarrio.com/category/luces-de-huerto-barriada-murillo/

-Taff

[Dick Fischbeck]

Beauty

[TaffGoch]

Ha! Surprise...

The "pallet" dome (the subject of another posting,) was designed/constructed by the same folks that designed the the Spanish nexorade dome.
http://control-zeta.org/

[Yaser Shahbazi]

Hi Friends
Yes. This Rotegrity has been made by Tabriz Islamic Art University - Architectural Technology Group in 4IASC congress that held in Shahid Beheshti University as one day Reciprocal Workshop.
The construction has started about 9 am and finished about 10 pm. There is a 3:47 TimeSlap that I attach for you in:
https://drive.google.com/open?id=0B0BbJ0fK36gwYllYZEFzWmhHTkk

[homespun]

I was inspired by the video of the construction of the Rotegrity Sphere in Tabriz, Iran, and by Taff’s templates and renderings to make a model which I finished today.  I used cardboard from cereal boxes.  If I have time I will make the “little brother” too.

                                          Dan

 

 

 

From: Yaser Shahbazi

Sent: Friday, January 27, 2017 5:11 AM

To: Geodesic Help Group

Subject: Re: New Nexorade/Rotegrity project

 

[biagiodicarlo]

A very good work,

bravo Dan!

- Biagio Di Carlo

www.biagiodicarlo.com

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[Ashok Mathur]

Dear Dan

Very Good Work.

Can you document the size of nexorades that you cut from cardboard,how many numbers of each type, what you used to join them etc so that others can also try to copy you?
Regards
Ashok

Regards

Ashok

On Sun, Feb 5, 2017 at 7:00 PM, Robert Clark <clark.rob...@gmail.com> wrote:

Very nice, Dan!  How are the connections made between the pieces?

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[TaffGoch]

Nice results, Dan!

I need to experiment with cardboard & (fiberglass) resin, and get started making some large-scale outdoor rotegrities. (I have no warehouse/museum.)
___________________

Ashok,

I posted the templates, above, in an earlier post to this thread (which Dan used.)
https://groups.google.com/d/msg/geodesichelp/RFBZ6uFmsjU/7dwOJJ8mBwAJ

You can always find them online, here, as well:
http://taffgoch.deviantart.com/art/Rotegrity-3v-1-2-625451741


http://taffgoch.deviantart.com/art/Nexorade-3v-2-1-Alternates-623335175

(NOTE: There are, in addition, several other dimensioned rotegrity tessellations, at my deviantART pages. I should have mentioned this earlier in this thread - mea culpa.)

-Taff

[homespun]

     I printed the templates on paper and cut them out.  Then I used glue stick to attach them to cereal box cardboard, and cut them out again.  I used a pushpin to make the holes.  Then to assemble I used pushpins and paper clips to temporarily hold a few straps in position.  I would remove the paper clips and push pins one at a time and use a stapler to make the permanent attachments.

     I used 60 short straps (0.113061), and I think it was 150 long straps all of the same size (0.132208).

     Just give it a little push and it rotates so nicely.  FUN! See 12-second video: http://tinyurl.com/hov7r67

                                           Dan

 

From: TaffGoch

Sent: Sunday, February 05, 2017 5:02 PM

To: Geodesic Help Group

Subject: Re: New Nexorade/Rotegrity project

 

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[Ashok Mathur]

Dear Taff

The two numbers that Dan quotes above (0.113061 and 0.132208) are not among the four numbers that you provide i.e. 0.15etc, 0.179etc,0.177etc and 0.18etc.

For me that is not the most important issue as I could just follow your numbers.

What has prevented me from implementing the rotogrity is that I am lost if the connections between the two strips is stiff and fixed in nature or the strips rotate about the connection point.

If it is stiff and no rotation is to be provided for, then a good adhesive or good staples will do the job.

If some relative motion is to be provided for, then some sort of bolts will be needed.

Can you clarify?

Thanks

Ashok

Regards

Ashok

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[homespun]

I used the red and the green ones.

                Dan

 

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[Ashok Mathur]

Dear Taff,

My understanding of what Dan has done, which is supported by the geometry is to reduce the four components to just 2. The smallest one and the largest one.

As a good approximation the smaller component is about 85% of the larger in size.

The four sets given here and the four sets given in the previous link are also inter-related. The set in the link is about 1.39 times the size given in the image here.

Regards

Ashok

Regards

Ashok

[TaffGoch]

Ashok,

One word: "Scale"

The dimensions that i provide produce a sphere of unit (1.000) radius. They are, therefore, arc "factors"

Multiply to produce the sphere size desired. Dan likely did so.

-Taff

[TaffGoch]

Ashok,

Regarding assembly, note that Dan did each connection in two steps.

You have to allow for some (minor) rotation, during initial joint connection. After multiple adjacent initial connections have been made, the need for rotational allowance is no longer needed. Final connections can then be "made" rigid.

I do ALL (not just some adjacent) initial connections with pins, then go back and "rigidize" all. The sphere turns out quite rigid & robust.

-Taff

[Ashok Mathur]

Dear Taff

Thanks for both the tips.

Soon I shall make one and report on the result.

Regards
Ashok

Regards

Ashok

--

[TaffGoch]

Food for "imagineering..."

Tower

Lozenge

-Taff

[homespun]

Just now finished “little brother”

                                Dan

 

[homespun]

Here are the two of them together on display at the hallway exhibit at my “OCTA-TETRA Museum”.

                             Dan

 

From: homespun

Sent: Sunday, February 12, 2017 11:34 PM

To: geodes...@googlegroups.com

Subject: Re: New Nexorade/Rotegrity project

 

Just now finished “little brother”

                                Dan

 

 

From: TaffGoch

Sent: Sunday, February 12, 2017 9:38 PM

To: Geodesic Help Group

Subject: Re: New Nexorade/Rotegrity project

 

 

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[Olga]

If  I want to build 3v, 2.1, but  have only 80 cm long struits, approx.120 - 140 pieces. How i can calculate the diametr of possible dome and where i can drill whole for connections ? Any idea? Sorry for my english.

[Ashok Mathur]

Dear Olga

In 3V dome, the longest length is called 'c' and it is about 0.41 of the radius.

That indicates that with struts of 80 cm length you can build a dome with 2 meters radius.

If you use a external  hub that extends the hub length, and you may be able to get upto 2.25 meters radius.

For exact numbers you can see dome calculator here http://www.domerama.com/calculators/3v-geodesic-dome-calculator/

Regards

Ashok

Regards

Ashok

--

[TaffGoch]

Olga,

First, a question. Do you plan on a nexorade, with straight struts?

...or a rotegrity, with curved bands/slats?

Second, you should note that 210 struts/bands are required for either 3v{1,2} sphere.

-Taff

[homespun]

Taff,

   Is that the difference between a nexorade and a rotegrity? -- straight struts vs curved slats?

                                 Dan

 

From: TaffGoch

Sent: Tuesday, August 01, 2017 10:28 PM

To: Geodesic Help Group

Subject: Re: New Nexorade/Rotegrity project

 

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[TaffGoch]

Dan,

It's comparable to the relationship between squares and rectangles, taught in high school geometry, i.e.:

A square is a rectangle, but a rectangle isn't necessarily a square (but can be.)

A rotegrity is a nexorade, but a nexorade isn't necessarily a rotegrity (but can be.)

Rotegrities (having curved nexors, approximating the curvature of the sphere) are, therefore, a subset of nexorades.

At least that's been my experience; how I've read/heard the terms bandied about,

-Taff

[homespun]

Taff, – thanks so much for the info. – Dan

           

 

From: TaffGoch

Sent: Wednesday, August 02, 2017 9:04 PM

To: Geodesic Help Group

Subject: Re: New Nexorade/Rotegrity project

 

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[Olga]

Dear Ashok,

thank you for the answer, i will try to use this calculator.
Do you have experience in using of struts of the same length for 3V dome?

Regards 

Olga

Regards

Ashok

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[Olga]

Dear Taff,

i have struts, which are a little bit curved. I use old bed sluts. I sown them to double the amount.they are also a Little flexible. 
I want to build a quarter of the sphere, as terrasse roofing. I will fix them with screws, becouse for the winter i have to move it away. 

[Blair Wolfram]

I'd like to see this.

Do you have pictures?

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Blair F. Wolfram
Founder, Dome Inc.

thedo...@domeincorporated.com

http://www.hurricanedomes.com

888-DOME-INC or 612-333-3663

[Olga]

I will post them if i make it. Now I am in the planning. But it is not so easy to calculate and to drill holes in the right position.

[Ashok Mathur]

Dear Olga,

While my answer to you is factually correct, it answers a different question than what you wanted to ask.

Taff has given the right answer if you are wanting to make  a Nexorade.

A Nexorade also needs 3 different lengths for 3V but two lengths are so close to each other that Dan has built it using only 2 lengths.

Regards

Ashok

Regards

Ashok

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[Olga]

Does it matter where the ends of the slats are for rotegrity construction (up or inside)? Does this change the radius or stability?

[Arnd Marijnissen]

On Friday, August 4, 2017 at 2:54:33 PM UTC+2, Blair Wolfram wrote:

I'd like to see this.

Do you have pictures?

On Fri, Aug 4, 2017 at 5:02 AM, Olga <olg...@gmail.com> wrote:

Dear Taff,

i have struts, which are a little bit curved. I use old bed sluts. I sown them to double the amount.they are also a Little flexible. 
I want to build a quarter of the sphere, as terrasse roofing. I will fix them with screws, becouse for the winter i have to move it away. 

I know it's already 2018 by now but I thought some others might enjoy this too.

Olga and I seemed to have had the same idea.

I saw a similar dome at the end of 2016 and have made a smaller version with standardized sized slats (80cm, with 76cm from hole-to hole connected simply with lockbolts and wingnuts. A plate ring to distribute the force onto the wood).

I have brought it to two events so far and the reactions of people who saw it has been more than positive.

This has led me to start building a bit more of a project around it in the hope that more people will follow the idea and bring one to an event so they can be joined together as a mini-dome village.

Since the material is cheap (trashed bed-bases) and the size is standardized (getting 80 slats of 80cm is doable. Getting 80 of 90cm is .. much harder it turns out), it'll mean that any covers, connections, door-frames, circular hammocks, internal projection-sheets , etc, will end up fitting in eachother's domes. 

Perhaps this design can do for Frame-domes what the Hexayurt did for Sheet-domes. Being cheap to build, re-usable to a higher extent (and not made of harmful foam-based sheeting), able to support loads (hammocks) and be great to look at to boot. 

I wont bore you further. Here's some pics.

For more information, see https://www.sociallife.org/data/dome  for a redirect to the wiki where I am documenting the construction, buildup, breakdown and labelling process as well as hoping to coordinate a mini-dome village meetup at hacker-events from.

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 Justa

[Olga]

Hello all, 

I`ve started my project. But something is not correct. Maybe because i have the same distance between the holes and the same length of struts?

Does anybody have one idea? 

Best regards

Olga

[Olga]

Hello all,

now i have a problem, that i have not enough struts of the same length :( 

If I take slightly shorter struts (2 cm shorter), should  I keep the distance between the middle holes the same and the distance between the 1 and the 2 and the 3 and the 4 will be slightly smaller. Will that work?

[TaffGoch]

Olga,

Based on your prior post...
       "I want to build 3v, 2.1, but  have only 80 cm long struits, approx.120 - 140 pieces..."
...and your photo, I've started on a 3D model:

It is currently unrefined, but I wanted to let you know that someone was working to address your questions.

-Taff

(aka, David Price)

[Olga]

Thank you Taff. It will help me. It looks now great. I'm curious if I can finish my proect this year.

[Nathaniel Virgo]

Hi TaffGoch

I'm thinking of building something based on this geometry. Can I ask whether the numbers in this image are chord lengths or arc lengths? That is, are they the lengths you would put between the holes before curving the rod to approximate the sphere surface, or are they the straight-line distances between the vertices of the resulting polyhedron?

(I appreciate that those two measurements will be very nearly equal, I'm just being unnecessarily obsessive about accuracy.)

Best regards

Nathaniel Virgo

On Tuesday, July 12, 2016 at 12:32:39 PM UTC+9, TaffGoch wrote:

Regarding the original nexorade post:

These chord factors will produce a sphere of unit (1.000) radius. Straps are depicted, but values are valid for each of the previously-depicted nexorades. (For color-coding, refer to the "rod" or "spring" depictions.)

-Taff

[Patrick Doyle]

Here's a pic of a rotegritoid sphere I put together a few years back. There's a bit more distance between the inner and outer struts, but for the minimal amount of material, there definitely was some compounded structural integrity.

I've seen some pics of a rotegrity dome in Russia that used layered struts with gaps between the layers.

Patrick

On Wed, Dec 5, 2018, 9:02 AM Robert Clark <clark.rob...@gmail.com wrote:

Has anyone considered building a nexorade dome using the bow-roof shed construction method? Ends of the curved struts would be bolted to the other struts just as shown in TaffGoch's diagram. But, instead of being flexed and under stress, they would be rigid and more structural.

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[Patrick Doyle]

[Bryan L]

Hi Nathan,

I believe they are the lengths before curving the straps

[Bryan L]

Hi Robert,

I have thought about trusses for traditional domes. I think I saw a video of a timber dome with 12" thickness in the shell (for insulation) where they use similar design to your pic just not bowed.

Certainly gives more strength for a rotegrity.

[Dick Fischbeck]

Any old way you put together struts with equal curvature, you get a dome.

https://www.flickr.com/photos/8152259@N03/488849779

[Levente Likhanecz]

Hi Nathaniel,
i succeded to repeat (build from scratch) the construct in sketchup on 100000mm radius. The 5 strut card sure listing arc lengths so my guess this 4 strut card should be same. if you wanna try it in sketchup first exchange them to chord length (fun-fact those arc lengths are equivalent to theta center angle as radians on 1.00000 radius). and use triangle built fan blade triplets. those 6 digits is not much for sharp joints. first i built the red penta fan. then between red blades the greens had minor difference to the list. then made a triangular fan of yellow-blue-purple. welded to of them along the yellow blade. that gave the most accurate 100000mm radius sphere built from top to bottom. so only the green blade was stretched on red fan all other colors used the taffgoch figures converted to cord length from arc. (sketchup measures arcs as sum of straight segments). excel attachment has some pics embedded.

[Nathaniel Virgo]

Hi Levente

Thank you very much for this! I'm using OpenSCAD rather than SketchUp, so it's a bit of a different process to reconstruct it, which makes the numbers you present very helpful indeed.

I am wondering if you also have the ability to calculate the angles between the struts? (I guess they would technically be the dihedral angles between the different coloured planes on the left-hand side of your screenshot.) That would be enormously helpful as well, if that's possible.

Best regards

Nathaniel

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[Levente Likhanecz]

hi nathaniel, unfortunately the sketchup is less scientific rather practical toy. angle measurements results max. 3 digit behind decimal point. my guess is not enough for accurate reproduction. i used to make common algebra in excel to get my 15 digit accuracy (or few vector algebra). so i will check how i can calc dihedral angles from those lengths. nothing promise cose i'm not a mathematical prodigy. i told the green blade is derived from red fan, on 100000 radius derived green 15381.473309 while taffgoch green is 15381.2971123. is not much different if you wielding with a hack-saw, but CAD.

the main problem i still don't understand the underlying geometry twist of taffgoch'es design i am more into class1 standard domes.

best regards, levente

 

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[Levente Likhanecz]

hi nathaniel,

my best guest for dihedral angles of these basic fans i attached as text file. i dont know if sufficient enough to start building, i raised perpendiculars on intersection line between colored planes (and layed on each plane) and these angles calculated between the perpendiculars. let me know if something works.

best regards, levente

[Nathaniel Virgo]

Great, thank you, that's wonderful, I will give those a go. I think the accuracy will be more than enough, as I'm not working on a large scale or anything. I really appreciate it.

Best regards

Nathaniel