Posted on July 12th, 2010 by ryan.
I’ve been looking into methods of excavating stone for a new project, and it turns out that the world of rock excavation is much more interesting than I realized.
If you’re looking for crushed stone, a rock drill and some dynamite is all you need, but to get large usable slabs of stone requires a bit more finesse. Cararra marble used to be quarried by drilling a series of holes on the edge of a cliff, inserting wooden ‘wedges’ and then soaking these with water – the expansion would cause the stone to crack along the line of holes and the resulting ‘bench’ was then moved to another facility to be cut to the proper sizes.
Modern methods are much cooler, and use two basic tools; gallery saws and wire saws. A gallery saw is basically a 12-foot long chain saw for cutting stone. They move along tracks and can cut either vertically or horizontally. Wire saws are basically big motors attached to a huge rubber band studded with diamond discs. The rubber band gets wrapped around the piece of rock you want to cut, then the wire saw pulls it tight and starts rotating it. The diamond discs slowly slice the stone in half, like a cheese wire.
This video shows one of those chain saws in action.
Here’s a horizontal cut
This shows the wire saw – isn’t the space created after removing the slabs amazing?
And here’s what happens after the cutting’s finished…