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Discussion Starter #1 (Edited)
A friend of mine is a sculptor who does free-form work in serpentine - a green rock, soft, with false-jade veins, quite pretty, California state rock. One of the best deposits is an exposed hillside in San Luis Obispo.

Serpentine is loaded with asbestos, so much so that the Air Quality Management District (AQMD) of San Luis Obispo county requires lots of watering to remediate airborne dust when trenching, excavating, or grading on your own property.

Here are two of his free-form sculptures, about soccer ball and US football sized.
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I took the van and got about 100 lbs to make spheres. These are small, dark, no obvious jade veins, but worth a try. The middle one is sawn into a cube, then an octahedral shape. Points and edges are hand-ground off to round the corners.
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Blue nail polish on the flats to visualize the surface of the sphere when grinding - when all the blue spots are gone, it's round.
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I built the sphere grinder from ideas on the internet, but it’s a toy machine. Seriously. Toy motors, 60rpm, 12 volts, 12 dollars each, mounted on a pivot arm with a compression spring on each side, so the pivot arms float back and forth a little as the rock dances among the grinding pads.

Built with hand tools only. Parts from Home Depot, Amazon, 80/20. Water drip for wet grinding, 1 drop every 2 or 3 seconds. Grinding pads are plastic impregnated with diamond grit in steps from 30 grit to 3000 grit, velcro backed, typically used for grinding and polishing kitchen&bath granite countertops or marble floor tile.

Has worked remarkably well for 3 years of intermittent use.
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After roughing the rock to a full round sphere, subsequently finer and finer grits are removing less and less material, merely taking out the scratches from the previous larger grit. Just like sandpaper, the grits are 30, 50, 100, 150, 200, 300, 400, 500, 600, 800, 1000, 1500, 2000, and 3000. 3000 grit = 6 microns.

Final polish is with 1-micron cerium oxide powder, wet into a paste, on plain rayon buffing pads. This sphere is the size of a tennis ball - 2.5” diameter (64 mm). It looked like a dumb dark rock until about 1000 grit when interesting features and character began to appear. After final polish, and in sunlight, it really pops. Took about 40 hours, half sawing, half grinding.
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Hope you like it. :)
 

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That's pretty frickin' cool. I liked reading about how it's done.
 

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Discussion Starter #4
That's pretty frickin' cool. I liked reading about how it's done.
Thanks, EddieZ.

I knew nothing when I started, and still am miserably uninformed, but having fun learning.

And, as my sculpture friend says, "Take what the rock gives you".

:)
 
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