How to make spherical shapes?(I'm new)

[markcable]

Got a few tricks I use I'd be glad to share.

1. I use the petal method on my own designs, but there's a little cheat that helps with the shape. At the base of the cut on each side of the petal, I add a horizontal slice across the point where the petals meet. it looks like this:



The orange lines represent the cuts. Sorry, crappy drawing. My models look much better than this.

Another trick I use is to apply thin CA glue to the rounded part and sand smooth when dry. I did that with my North Korean HS-16, but the structure uses both stepped cones and petals:


Once the CA soaks into the paper fiber and dries, it becomes hard like plastic, so it can be sanded. Then, I painted the nosecone. This also works to strengthen load bearing structures like the engine truss at the bottom of a Titan or the lattice work between stages on a Soyuz or Long March.

[dhanners]

I've also found these -- burnishing tools intended for dry transfers -- to be helpful in pre-curling petals. (Used with a computer mouse pad, of course.)

[Gil]

Assembly of open petal design tutorial download:

This might help;

http://www.papermodelers.com/forum/v...le&fileid=3332


-Gil

[silverback920]

Quilling, where you roll a strip of paper into a disc, then push the center of the disc downward to form a cone. Carefully work the various layers into a spherical shape then glue. This can be pressed into a dapping block of the appropriate size for a near-perfect sphere.
As mentioned, CA glue and sand for a super smooth surface.

[Paper Kosmonaut]

Originally Posted by markcable

Got a few tricks I use I'd be glad to share.

[there's a little cheat that helps with the shape. At the base of the cut on each side of the petal, I add a horizontal slice across the point where the petals meet.]

*Jaw drops* This. Is. Fantastic. Ten+ years in the hobby and I never heard that before. To me this is totally new. I never had much trouble with either petals or ring-shaped cones or balls but this little trick is genius. and increases the roundness of the cone significantly. Wow.
Thanks Mark!

[markcable]

Glad that helps! I may add that to my future kit designs.

[DriveWRX]

Thanks everyone! These are fantastic tips.
My main modeling interest is race cars, so I rarely encounter spherical shapes, but knowing/learning new techniques is always good...

[cgutzmer]

agreed! Petals have been one of the banes of my own paper model building, now I need to find a build to try it on!

[USSMissouri]

Very helpful.

[airdave]

Coincidental timing, but very recently I had to construct some spheres in paper
and I rediscovered one of problems I have run into before (with full spheres)...

in this case I wanted to add the three "Flotation Bags/Balloons" to my Apollo Capsule model.
There are three of the inflated bags, two larger, one slightly smaller.

Over the years I have saved various paper model templates of spheres.
Some are harder to construct, some a bit easier, some better for larger spheres, some better for smaller.

And because of the coloured pattern on the larger fabric bags, I pulled out a sphere template that is comprised of hexagon and pentagon faces (like the real thing).
So its not actually a sphere, it is a goldberg polyhedron...but the more faces (hexagons and pentagons) used gives it a smoother spherical shape.

Goldberg polyhedron - Wikipedia



Anyway my point is, whatever template you use, the problem with paper spheres is the final closure of the sphere.
Whether you build two hemispheres and connect them, or work you way down to one last panel to close the sphere...
those final connections and closures are where you make a mess!

Or, I make a mess!



Connecting paper things is easier when you have access to both sides of the paper connection.
Closing up a sphere means you don't...you only have access to the outside.
And it becomes a challenge to finish your construction.

If you are making hemispheres or domes, things get a bit easier.

Everything went well assembling the small panels on my Flotation Bags until the last few tabs and closures.

I guess my point is, one sphere template is no easier than another because they all require those final difficult closure steps...and all paper spheres will be made up of flat panels and flat faces.
So choose a pattern or template that better matches the final objective (type of sphere and its application).

In my case, I am trying to recreate flotation bags that were originally made of flat fabric panels (hexagons and pentagons) stitched and taped together.
So a paper goldberg polyhedron (with close to the same number of faces) is the best option.

If you were constructing a World Globe, vertical petals might be a better option since that it exactly how globes have been constructed by map makers for centuries.
But its still those last connections and closures that will give you the most trouble!