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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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#1




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 
#2




"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 
#3




"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. 
#4




"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 needthen 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




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 
#6




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




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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