Hi Sara,
I have some flat pieces of Agate that I need to drill holes through. Does anyone have any tips on how to do this without the Agate cracking?
If it were me, I get a diamond core drill of the required size. Core
drills are tube shaped drills that have diamonds either plated or
embeded on/in one end. There are usually a couple of holes in the
side of the tube to allow water to enter & exit. The water cools &
lubricates the bit while drilling. It also flushes the cut rock
particles away.
To drill the holes, you’ll need a drill press & a waterproof pan
large enough to hold the slab that’s being drilled.
Place the core drill in the drill press & the slab in the pan. There
should be enough water in the pan that the slab is covered & the
cutting end of the drill is covered by about 1/4incnh (6mm) of water
while drilling.
Use a drill speed proportionate to the drill size. The smaller the
drill the faster the drill should run. Keep a steady (not to heavy)
pressure on the drill as it cuts. The slab should be held securely to
prevent the drill from grabing it & spining it around. Periodically,
the drill should be raised from the cut to aid in flushing the cut
rock from the hole.
If the hole is small, less than 1/16 inch (2 mm), there are small
solid, plated or sintered diamond bits available that could be used
in a flexshaft or motor tool. If this option is used the slab needs
to be covered in water as above & the drill needs to be removed from
the hole more frequently to flush out the cut rock.
Dave