Drilling alabaster

[Bernd Buerklin <bernd@zzzzzzzzzzzzz>]

Hi,
I just drilled 8 marble balustrades all the way through, 3/8th hole, 18
inches long. The balustrades are less than 2.25" diam. at the smallest
point. They are old, from France, brittle. I used a SDS plus machine in
hammer drill mode. First with 1/4" bits and a selfmade guide to keep the
18 inch long bits straight. Then with the 3/8" bits. Success, but scary.
The SDS machine is very aggressive because it is made for concrete
drilling. It takes a sensitive hand to control that beast. The trick is
to really keep the bits straight and the hammer force straight down that
way. The slightest changes in angles produces force on the stone because
the bit bends and pushes against the inner wall of the hole. This can
split the piece.
Of course I would have liked to use a 20" center waterfeed diamond core
bit on a 40" travel drill press. I just could not find that anywhere nearby.
I would not use SDS hammers on alabaster. If at all maybe a normal
hammer drill. There are two kinds of drill bits that I used succesfully
on softer stones with just a drill: My first choice is ARTU, a bit that
can drill anything. It does have a special carbide tip. Stays sharp
pretty long. Second choice is Bosch Blue Granite carbide bits. They are
not as sharp as ARTU and specialised for masonry, but still work pretty
well without hammer action on the drill.
Try what works best for you! Bosch bits are cheap and ARTU bits are a
good deal, affordable I would say. Or well worth it in other words.
Good luck!

Bernd Buerklin
Stone Doctor