How do I drill something that is very hard and brittle?

I have acquired a large quantity of otoliths, the hard ear bones of a fish, which I would like to drill for use as beads. But they are very hard, and very brittle, and they always shatter when I try to drill them will a conventional electric drill bit.

Any suggestions?

I’ve used a 0.75 mm diamond drill bit to make small holes in granite. They should work on ear bones as well.

Generally drilling of extremely hard materials is done at (relatively) low speeds, often with fluids and abrasives, however, unless this stuff is fossilized a standard diamond or carbide bit ought to make short work of it.

See what drill bits and techniques gemologists use. It should suffice for your purposes.


Drilling rocks

Have you tried a Dremel drill. The little hand held jobs that spin at 20-30,000 rpm.

It’s the oposite of what astro said about drilling slow. But the Dremel is pretty cheap, and may be worth a shot.

I would try an abrasive ‘grinder’ type bit (they make them very small) instead of a standard drill bit. I bet it would be a piece of cake.


Fish ear bones. Huh.

I learn something new here every day.

I’ve found Moto-tools to be an excellent way to melt expensive, small drillbits, such as the diamond bit I linked to. Slow is the way to go with hard, brittle objects.

Diamond drill bits are the way to go. Add 2 or 3 small drops of diswashing liquid to a cup of water to use as a cooling agent. Slow to moderate speed gets the job done.