These crystallography ball toys display an endless arrangement of 2D hexagonal (and sometimes cubic) crystal grains as you tilt or shake them.  They show holes and crystal defects as well as dislocations that form and move as you disturb them.

They also show an unexpected behavior.  A few seconds of vigorous shaking generates static electricity within the toy and causes the balls to weakly repel each other.  The result is a fascinating flow of balls as they levitate and avoid each other while rolling downhill.

I saw a video about an educational toy made by François Dallegret called "Atomix" and really wanted one.  There weren't any available though so I decided to make a couple of my own.  They were really fun and popular so I decided to make more so that other people could enjoy having one.

These toys are made with 2 pieces of 3/8" (9.5mm) thick acrylic which sandwich a 0.090" (2.3mm) 6061-T6 aluminum spacer.  The parts are held together with 4 aluminum Chicago/binding screws trapping roughly 1,800,  2mm (0.079") stainless steel balls inside with a small gap allowing them to roll freely.

I personally make every single toy in my shop in Bryan, Texas.  The first step is taking a 6"x6" acrylic blank and placing it on a custom fixture in my CNC router.  The vacuum fixture holds it firmly with suction while the router mills the profile and binding screw pockets with a sharp O-flute bit.

After making two acrylic blocks I switch programs and use the same vacuum fixture to machine the aluminum spacing shim.  This part is more difficult than the acrylic because the internal stresses from cold rolling the aluminum sheet causes it to curl up and let air underneath the part.  This took a few tries to get right and required milling a large number of individual pockets on the inside of the part to control warping until all the material was removed and a final finishing pass can be taken.

When the shim comes off the CNC it is ugly and scratched up so I de-burr the part and give it a "brushed" finish with sandpaper.

Now all the parts are ready for assembly and I weight out the balls, remove the protective paper on the acrylic and stack the toys.  They aren't done yet though, there is one final step.  That is polishing the edges.  After milling the cut profile of the acrylic has a frosty look that is good looking but not quite as attractive as a clear edge.    The easiest solution to this is to use a propane torch and flame polish the edges.  This works very well and doesn't take very long but it is a delicate operation.  I have to use just the right amount of heat to completely melt the surface of the acrylic and let surface tension pull out all of the micro scratches that make the surface frosty.  Too much heat though and the acrylic starts bubbling up and catches on fire!

5.8" x 5.8" x .84" (147mm x 147mm x 21mm)

1.4lb (650g)

Science Toy, Educational Toy, Crystal Structure Toy, Lattice Structure Toy, Desk Toy