# Making domes/hemispheres??

Discussion in 'General Card Modeling' started by dhanners, Aug 3, 2004.

1. ### dhannersMember

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Hey, all.... I'm working on a scratchbuilt project and have a need to fabricate a hemispherical piece. I know there are online "shroud" calculators where you can plug in the size of the shroud you need and it spits out the arc sizes and degrees, but is there some similar tool (or software) that card modelers use to make domes or hemispheres?

I'm about to launch into trying to build it via trial and error, but I thought if anyone knew of any sure-fire methods or techniques, they'd be here.

Any guidance/tips/hints/warnings would be appreciated. Thanks.
David Hanners
Minneapolis, MN
2. ### GilActive Member

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David,

I don't think anyone remembers the formula for lunes the common name for "gore panels". Just knowing the name is good enough for a google. Most of us use CAD 3D primitives to generate spheres. An alternate CAD method is to rotate a 2D profile through 360 degrees through smaller degreed steps (i.e 360 divided by the number of gore panels equals the degree step). A similar manual method can be developed using the old two view method (top and side views) to plot the intersection points followed by fitting the points with appropriate french curves. Domes are simply a truncated case and can be developed with this method.

Best regards, Gil
3. ### dhannersMember

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I hate to sound dense, but you lost me at the word "lunes"....
4. ### GilActive Member

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David,

Lunes comes from the Latin Luna or Moon. Think of the area formed by two overlapping radii. That's a lune or in ballon jargon a "gore".

I'll generate a graphic later today that will explain.

Best, Gil

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6. ### Sticky FingersMember

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This got kicked around about 18 months ago on the old site. Some of the stuff still might be in there about a different way of generating spherical and elipsoid domes. Basically what I've been trying is to have the pannels radiate from the top or center

http://img.photobucket.com/albums/v19/markandannie/Gumdrop Design/domeskin.jpg

The screen capture is from one done in AutoCAD. The arrow denotes just where the primary seam is. It extends all the way to the center of the dome (one could aslo probably get away with just cutting all of the seams to the point where the center pie shaped sections are and forming the top of the dome over a ball. Well I still see I have not got the attachment thing figured out yet

This is a shot of one of these from the lod site so you can get an idea just how they go together.

http://www.cardmodels.org/mega/photos/show-album.asp?albumid=168&amp;currentpos=17
7. ### GilActive Member

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Manual Hemisphere Panel or Gore Development

(See update below)
8. ### Leif OhMember

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Gil, please upload to the appropriate section of the parts bin. Would be very good to know that this is archived somewhere.

Leif
9. ### wunwinglowActive Member

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I think we just blew orcberto's bandwidth allocation out of the water....

Tim P
10. ### GilActive Member

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Manual Development Methods; Hemisphere

Pluribus et al,

The figure below shows a manual method for developing gore panels or lunes for a hemisphere. Note that the panels can be mirrored at the bottom to form panels for a sphere. Stretching the longitudinal segments will yield a hemi-ellipsoid useful for a great variety of 3D shapes. The other method of unwrapping a sphere is called "zone" and is much more difficult to manually develop.

Best regards, Gil
11. ### Sticky FingersMember

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Dave, this will generate all manner of platonic, archimiedian, catalan, johnson and geodesic solids. The fully useful version around \$20 if memory serves. The base downloadable version is just fun to play around with. Just the geodesic section list around thirty different t types of structures in both the sphere and dome

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13. ### SCEtoAuxMember

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This might work

Here is a link to a page where you download a pattern for a 3v 5/8 dome. It is made up of a bunch of triangles and looks kind of like the dome on an observatory building where the telescope is. The 3v means 3 frequency and the 5/8 means it is about 5/8 of a full sphere. You print out five pages to make the dome. The page is in German. 'Klebefalz' is where the tabs should be. There is one place on the right that does not have that word, but you need a tab there too. It is between two of the 'A' sides. 'DOME Grundlinie' is the ground line for the dome. The resulting dome is about 9.5 inches (241.3mm) in diameter and about 6 inches(152.4mm) high (radius). These are just rough eyeball measurements. You could print the five sheets needed to make this dome and construct it and get an idea of what it looks like, then scale the diagram to get the size of dome you want the next time you print.

3v 5/8 dome

Here is a place where you can plug in the radius you want and it will give you the length of the sides (struts) of the triangles needed to build a dome. A 3v 5/8 dome needs 30 AAB triangles and 75 BCC triangles. That is a lot of triangles to cut out, but you can get a nice looking dome to whatever size you want. There are calculators for other dome frequencies too. (I made a 2v dome playhouse out of 40 large cardboard triangles.) The higher the frequency the smoother looking the final dome will be. You'd have to figure out how many triangles you would need for the other domes, though. Hopefully the 3 frequency (3v) dome will suit your purpose.

Desert Domes Dome Calculators

Hope this helps you in some way.
14. ### Sticky FingersMember

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When I get the time I'll write somethoing up to explain the process depicted here. All of the operations are done in AutoCAD but any similiar drafting program should be able to do the same ting. The technique works for both spherical and elipsiodal domesand also partial domes

http://photobucket.com/albums/v19/markandannie/Dome Generation/

Note there are a cople of extra pictures in the slide show one of them being the first angular measurement.