jamius.com

Ugh, I can't figure this out. Maybe I should just think about it more.

But anyway. To build a dome, you need the ends of the pieces to be bent.

To build a tube, not all of them need to be bent. I can't figure out which need to be bent and which don't.

So here's the hexagon (since a tube is all hexagons and no pentagons.)

......A....B
...../..\ /..\
....F....G...C
.....\../ \../
......E....D

For a dome, A through G all have to be bent at 12 degrees. The inner pieces A-G, B-G, C-G etc are a little longer than A-B, B-C, C-D etc. The angles as well as the size difference gives the hexagon a "bent" look, it's bent in all directions. (Like the outside of a sphere, duh)

So for the tube, I used all of the same size pieces. (I'm modeling it after a carbon nanotube, which has all same size bonds.) After that, I'm stumped. I'm going to do some more research (and maybe build a carbon nanotube on the computer modeling program.). I just figured that since there is at least ONE person here who has built one, I could get some hints.

Thanks!

EDIT: Quick math. 15 Bonds around the tube = 24 degrees per bond. BUT the angles aren't straight.... meh.

EDIT2: 24 degrees per bond = 12 degree bends. (I feel stupid).

I think I've figured it out.

The ends of A-B and E-D should be bent at 12 degrees.

Also, one end of F-G and G-C should be bent at 12 degrees. I bent the inside edges (at point G). This SEEMED to work, but I am working with a very malleable substrate (aluminum). I'll try to build one out of thicker steel tomorrow (so then if it's bending somewhere it shouldn't be I'll know it.)

Now that I think about it, the other ends of F-G and G-C might have to be bent as well.

I would like to know this I'm no help though.

My guess is that you can determine the angles because the joints touch the sphere at the diameter length. So, you have an equilateral triangle. The two equal sides are the length of the diameter radius of the sphere. You know the strut length. It should be simple math from there.

I've figured it out (a while ago actually).

Only 4 pieces need bent ends. They are the pieces that go AROUND the tube. The pieces that are parallel to the ground need 12 degree bends on each side. The rest of them are straight (or straight enough that you should be able to bolt them in place easily enough.) If you have a hexagon (which the tube is made up of) And you are holding it so that there are 3 "rows" that are parallel to the ground, all three of those rows should be made up of bend end pieces. The diagonal pieces are not bent.