Drawing dots evenly on a sphere.

I have a little project/experiment that I’m planning wherein I will make a magnetic pseudo-monopole. (Just for the heck of it.)

I went up to Michael’s yesterday and bought a 2 1/2’’ diameter wooden craft ball, and I want to embed 60 1/4’’ diameter x 1/8’’ thick NdFeB magnets evenly on the surface of the sphere, as shown in the n=60 triangulated diagram on this page.

My problem is that I need to be able to mark those points on the sphere for drilling, but I have no idea how to do it. Does anyone have any idea of how I might go about doing this? Thanks in advance for any help; this has me stumped.

mounting the ball accurately cantered between two dead-centers in a lathe, preferably an engineering one(becouse of the accurate cross/top slide) would be a good start.

How accurate does it have to be? I was thinking that maybe you could unwrap a sphere and lay out a soccer ball template (UV map) Or maybe just part of one as long as it is all symmetrical when done, and then transfer it say on a piece of latex and then apply the template to your wooden ball, I would think just part of a template might be best to avoid too much distortion. Mark your points and then reposition the template to the next section. Just a thought…
Maybe you can glean a bit more infohere and make it work in blender?
Some pattern ideas here.
It seems that scaling would be your main problem.

Hmm… That link and your printing idea helped. Perhaps if the magnets are arranged in a ‘buckyball’ fashion it might go something like this:

  1. Print out or draw a hexagon of the correct size on a piece of paper.

  2. Lay it on the sphere surface and mark corners.

  3. Keep moving hex template and marking corners until ‘buckyball’ figure is complete. The pentagons will automatically form from the negative space left by the hexagons.

As you said, scaling would likely be the most difficult problem. The hex would have to be exactly the right size to cover the sphere surface, and the shape may even have to be altered to account for spherical distortion.

Now, how to accomplish that…:confused:

Here is some info on scaling for your project. I suggested using latex as a template because I think that it would conform to a sphere better than paper, less wrinkling etc.

That is very helpful, thanks a bunch!

So far it looks like the edges of my hexagons need to be just over 1/2 an inch long to work. I’ll probably construct it with a straight edge and compass rather than try to print one out at the correct scale.

No problem, it is rainy here, I am taking the day off and got bored. I guess that I should thank you.
Looking atthis layout it would appear that you only need two small templates to construct your points. you will have to flip them as needed. You will notice that points do align up to each other in a regular manner across the whole of the layout.

Have fun!

I will! I’ll be sure to post pictures when I’m done, too. I’m hoping to get the ball to levitate on a magnetic trench or bowl.

I ordered the magnets today, but I don’t know how long they will take to ship.

Cool! I think I see where you are going with this. Sounds like a fun project. One thing, the holes where you insert your magnets should be as close as possible aligned toward the center of your sphere. A really steady hand and a good eye might be good enough, but you may wish to make a jig of some sorts to assist you with this task. Heh, magnetic normals if you will. Along these lines, maybe some more info for you to look into as you proceed with your quest.
Maybe here as well.

Yeah, I’m planning on using a jig to help keep the holes straight. :slight_smile:

Tomorrow I have to go buy a new compass to construct my hex template with; my current compass wont hold the graphite securely anymore. :frowning: Piece of junk…

I have the magnets now, and I have attempted several times to get a nice buckyball configuration of points on the sphere. My latest attempt was almost ok, except for 3 deformed cells (2 hexes and a pentagon) that I find unacceptable. Each time I have been varying the radius of the hex by a small amount; hopefully my next try will be a perfect fit.