Spike has been turning stone since 2003. He got turned on mostly because of curiosity and because he wanted to explore something besides wood. Check out his website for some the amazing work he does.
He especially likes Italian Alabaster, which produces a translucence you can not find in wood. He accents his pieces with wood. But you must be careful, expanding wood, e.g. segmented ring, can crack the stone. He demonstrated turning Brazilian soapstone. There is also Colorado alabaster, which is a gypsum class of mineral. Alabaster dust is lighter than soapstone, which has a heavier dust and therefore didn’t bother us so much when he does a bit of turning that night.
Some brief comments about the technique/tools, etc.
Don’t turn fast; the right speed is about 200-300 rpm
All finishes are a wet sanding process with micromesh. He starts with dry sanding up to about 150 grit. He wets with water
Spike first tried HSS tools and almost gave up. The stone dulls the tool far too quickly. But he built a carbide tool using 3/8 by 3/4 stock to prevent bending. He doesn’t need this to be tool steel because it just hold the carbide tip.
Mounting: most stone comes in cylinders; the rest comes in cubes or blocks. He avoids blocks because the cylinders are more cost effective because of time and shipping. This also guarantees that you get a solid chunk of stone.
A 6” chunk of stone costs about $50 before shipping. He orders $000’s worth at a time.
No 2 stones are alike.
For a finish he uses a wipe on urethane.
For segmenting and wood, he uses a good 2-part epoxy. For mounting the waste block to the stone and for visible joints he uses a marine grade; it is a slow setting epoxy and forms a really deep good bond.
The tools are basically scrapers; using a gouge defeats the purpose because the edge comes off. He also has a heavy hollowing rig.
He now sells his tool with 2 carbide bits for $90. They are also available at woodcraft in Red wood City/San Carlos.
A nice thing about stone is that there is no grain problem.
He does18 piece segments using a stable wood for the top or base or both. Because wood expands along width, using segments limits expansion and contraction and avoids breaking the stone.
Sources are on his web site.
Stone can be cored. Also called trepanning.