glueing slabs together to make spheres

Before I had any rocks suitable for spheres, I found 3/8+" thick marble floor tiles at Home Depot. The top polished surface is scratched with sand paper to give the glue some grip, using ordinary super glue. Don't skip this step. Ask me how I know.

The rest of the process looks like this...

Cut to 3" squares



Layout and saw octagons



Octagons



Octagons



Simple glueing fixture



Not shown is wax paper between tiles and fixture.
There is a surprising amount of glue squeeze-out which will glue the tiles to the fixture. Don't skip this step either.



These are destined to be little planets with polar ice caps.



Simple octahedral fixture.



Octahedral fixture



A bigger saw cuts the right-most vertical surface. Bigger because the cut is too high for the blade on a 6" trim saw. Note the wood shim (under the south pole) to allow the rock to protrude far enough so the blade clears the v-blocks.



Ideally the flats are coincident with points on the sphere's surface. Inked with a Sharpie pen to show the low flat spots. When the ink is gone, it's round.



Glad I started with marble tiles because it is a lot softer and easier to machine than quartz or jasper.



Takes a nice polish too.



Hope that helps.