An angle grinder that costs $10 new is worth exactly
that. You’ll keep buying better ones until you get one
line with your diamond wheel (Figure D). Don’t cut
yourself. I did, fortunately not badly.
Chisel off the end of the stone, then grind the end
of the stone flat.
WARNING: The angle grinder is an
incredibly dangerous and useful tool. Wear
safety goggles, or better yet a full face shield
and leather protective gear. An image search for
“angle grinder injury” will scare the hell out of
you. You’ll want a guard on yours.
(Unfortunately mine is missing its guard because
I found it that way in the trash. The former owner
threw it out when the switch burned out. The replacement switch cost a few dollars online.)
The diamond abrasive disk is a “dry cut segmented” masonry blade. Imported ones are available
online for a few dollars, or wherever cheap tools are
sold. Mine was $7. Goes through granite like you
wouldn’t believe. Opens up whole new worlds of
recreational stone carving. Don’t accidentally open
your veins with it, OK?
Carve the Bottom
Let’s get started. Does the stone “ring true”? Hang
it from a cord and tap it all over (Figure B). The ear
reveals a few spots where cracks and flaws deaden
the sound. Nothing serious.
Mark a cutting line for a flat bottom of the bowl.
A tin can or plastic tub flexes to make an approximately planar line around the stone (Figure C).
Clamp the stone securely, then cut around the
Carve the Lip
Mark a cutting line for the lip of the bowl. I used this
high-precision height gauge (Figure E). Clamp the
stone, then cut all around the line as deep as you can.
Split the end off the stone with a wedge (Figures F
and G). You just made a lid for your bowl!
Hollow the Bowl
Mark the inner edge of the lip of your bowl. Cut
slots into the bowl (Figure H), and then break out
the standing stubs of waste with a chisel or wedge.
Repeat to achieve your desired depth.
Grind the Inside Smooth
Grind the inside of the bowl smooth with the edge of
the grinding wheel (Figure I). You’ve made a bowl!
This article shows the first bowl I ever made. It
took two hours according to the time stamps on my
photos, and most of that was taking pictures and
various distractions. Who knew stone carving could
be so easy! Diamonds really are a girl’s best friend
after all, and the rest of us, too.
Enjoy your bowl, eternity! Hmm. How’d that be for
Tim Anderson (
mit.edu/robot) is the co-founder of Z Corp.
See a hundred more of his projects at