Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

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Joatman71
 
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Default Making a 10 sided dome

I want to make a dome (1/2 sphere) that is made up of 10 metal
"triangular" sections. It will not be a true 1/2 sphere. Each
metal section will be bent in only one direction and will be straight
in the other. The base and each horizontal cross section will be a
Decagon (10 equal sides). Each vertical cross section will be some
sort of a 1/2 circle. I am trying to figure out how to make the 10
"triangles" so that the sides will touch when bent.

If I take 10 isosceles triangles and arrange them so their bases form a
Decagon then bend the points in to touch each it will form a dome, but
the triangles will not touch along their sides, only at the base and
the top. The sides of each triangle need to be curved out. Is there
any way to make this proper curve without trial and error? How is it
best done using trial and error?

Thanks
Scott

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Lloyd E. Sponenburgh
 
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"Joatman71" wrote in message
ups.com...
I want to make a dome (1/2 sphere) that is made up of 10 metal
"triangular" sections. It will not be a true 1/2 sphere. Each
metal section will be bent in only one direction and will be straight
in the other. The base and each horizontal cross section will be a
Decagon (10 equal sides). Each vertical cross section will be some
sort of a 1/2 circle. I am trying to figure out how to make the 10
"triangles" so that the sides will touch when bent.



The name of the shape (item) you're trying to make is "gore". Do some
searches on calculating the dimensions of "gores". They're most made of
fabric for making hot air balloons and parachutes of the older spheric or
parabolic geometries.

LLoyd




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carl mciver
 
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"Joatman71" wrote in message
ups.com...
| I want to make a dome (1/2 sphere) that is made up of 10 metal
| "triangular" sections. It will not be a true 1/2 sphere. Each
| metal section will be bent in only one direction and will be straight
| in the other. The base and each horizontal cross section will be a
| Decagon (10 equal sides). Each vertical cross section will be some
| sort of a 1/2 circle. I am trying to figure out how to make the 10
| "triangles" so that the sides will touch when bent.
|
| If I take 10 isosceles triangles and arrange them so their bases form a
| Decagon then bend the points in to touch each it will form a dome, but
| the triangles will not touch along their sides, only at the base and
| the top. The sides of each triangle need to be curved out. Is there
| any way to make this proper curve without trial and error? How is it
| best done using trial and error?
|
| Thanks
| Scott

This is actually a mathematical question. Not saying the folks here
can't help you, but the math groups for sure can. There are a number of web
sites, some even which have small programs to go with different shapes. I
remember starting with "dome home" and going from there to find about all
the shapes and the math to get there. I think for your project, a shape
more like a soccer ball, with a mix of five and three sided figures will
work best. I forgot the exact name, something like truncated isodecahedron
or something.

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Leo Lichtman
 
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Default


"Joatman71" (clip) Is there any way to make this proper curve without trial
and error? How is it best done using trial and error? (clip)
^^^^^^^^^^^^^^^^
Look in a map book. One of the ways of developing a global map is commonly
seen in geography books and atlases. Or, you could carefully peel an orange
to produce the shape you want. Or you could cover a ball with masking tape,
and then make the required cuts to produce the shape you need--then
carefully peel it.

Another idea is to take something like a croquet ball and hold it against a
belt sander until the outside is converted to the shape you are aiming for.


  #5   Report Post  
 
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Look in a drafting or sheetmetal layout text. This problem is similar
to fitting the end of one round duct to the side of another one.
jw



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Dave August
 
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Now you see why Bucky Fuller invented the Geodesic dome, all panels are flat
and the math is simple.

Go google Geodesic Dome and make your life simple and have some fun.

--.- Dave

"Joatman71" wrote in message
ups.com...
I want to make a dome (1/2 sphere) that is made up of 10 metal
"triangular" sections. It will not be a true 1/2 sphere. Each
metal section will be bent in only one direction and will be straight
in the other. The base and each horizontal cross section will be a
Decagon (10 equal sides). Each vertical cross section will be some
sort of a 1/2 circle. I am trying to figure out how to make the 10
"triangles" so that the sides will touch when bent.

If I take 10 isosceles triangles and arrange them so their bases form a
Decagon then bend the points in to touch each it will form a dome, but
the triangles will not touch along their sides, only at the base and
the top. The sides of each triangle need to be curved out. Is there
any way to make this proper curve without trial and error? How is it
best done using trial and error?

Thanks
Scott



  #7   Report Post  
Joatman71
 
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Default



Lloyd E. Sponenburgh wrote:
"Joatman71" wrote in message
ups.com...
I want to make a dome (1/2 sphere) that is made up of 10 metal
"triangular" sections. It will not be a true 1/2 sphere. Each
metal section will be bent in only one direction and will be straight
in the other. The base and each horizontal cross section will be a
Decagon (10 equal sides). Each vertical cross section will be some
sort of a 1/2 circle. I am trying to figure out how to make the 10
"triangles" so that the sides will touch when bent.



The name of the shape (item) you're trying to make is "gore". Do some
searches on calculating the dimensions of "gores". They're most made of
fabric for making hot air balloons and parachutes of the older spheric or
parabolic geometries.

LLoyd


Thank you so much. I found a few good pages that helped me
tremedously.

Scott

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