Sphere inside of a sphere with no seams... possible???

[Selvagem85]

hello everyone.

I had an idea the other day for an item where i would need to embed a small spherical object in the middle of a larger transparent sphere of clear resin. The problem is that, for the life of me, i can't seem to figure out how to accomplish this without leaving a visible seam or leaving a larger-than-necessary flat spot on one side. I think the easiest method would be a two-part mold but that would leave a seam around the equator of the sphere. i asked a few friends who work with resin on a daily basis for help and they were having a hard time coming up with anything.

If there was a way to cast it in a one piece mold or remove the seam/cover it up i am unaware of it at the moment. Any help on this would be greatly appreciated, i feel like i have been spinning my brain wheels on this for far too long.

 

[Abelugo]

if you blow a bubble inside a bubble, there should be no seams, just food for thought. Interesting problem.

So are both spheres transparent?

Is the inner sphere centered or floating in the center?

Is the inner sphere loose so it can roll around?

 

[robn1]

The seem in the clear resin can be sanded smooth and polished back to clear. Suspending the inner sphere may be a problem, but it can be done in multiple pours.

 

[Selvagem85]

only the outer sphere is transparent. the inner sphere is a solid color and ideally should be dead center in the larger transparent sphere

 

[Malphas]

Might try and find how those foshigi balls are made. Sounds like what you're trying to do.

 

[DrewSmith007]

This might help:

https://www.youtube.com/watch?v=YUnvjnQoPnE

 

[Mike J.]

That's how they made the 'balls' in Minority Report: wood spheres cast in clear cylinders of resin, then cut down into spheres again and polished. A lot of work, I'm sure, but it can be done.

 

[C17ldmstr]

Single pour:

Start with a complete spherical mold with a pour hole slightly larger than your inner sphere.

Suspend the inner sphere using a solid, very narrow, rod of aluminum or steel (or wooden dowel?). Bond the rod to the sphere utilizing an agent that will release with a slight twist. Or better yet, secure a hollow tube which can be released by passing a smaller rod through the tube separating the sphere.

Start the poor and when the inner sphere is 90% encapsulated by the resin, gently release the rod and finish the pour.

Once complete, you'll need some effort to remove/polish the remnants of the pour hole.

I've no idea if this will work (buoyancy may play a role depending on size/weight, etc of the inner sphere), but it makes sense in my head. Maybe it'll help create some other solutions for you. Perhaps leave the narrow suspension rod or use a clear acrylic rod?

Good luck!