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

**URL:** <https://boards.straightdope.com/t/how-do-i-drill-something-that-is-very-hard-and-brittle/260850>\
**Category:** Factual Questions\
**Created:** [August 21, 2004, 3:15pm UTC](https://boards.straightdope.com/t/how-do-i-drill-something-that-is-very-hard-and-brittle/260850 "2004-08-21T15:15:32Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![Fear\_Itself](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fear_itself/32/19637_2.png) [@Fear\_Itself](https://boards.straightdope.com/u/Fear_Itself)\
**Post date:** [August 21, 2004, 3:15pm UTC](https://boards.straightdope.com/t/how-do-i-drill-something-that-is-very-hard-and-brittle/260850/1 "2004-08-21T15:15:32Z")

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I have acquired a large quantity of [otoliths](http://mysite.verizon.net/~fmurtley/otoliths2.jpg), the hard [ear bones](http://mysite.verizon.net/~fmurtley/otoliths2b.jpg) 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?

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**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\
**Post date:** [August 21, 2004, 3:42pm UTC](https://boards.straightdope.com/t/how-do-i-drill-something-that-is-very-hard-and-brittle/260850/2 "2004-08-21T15:42:57Z")

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I’ve used a [0.75 mm diamond drill bit](http://www.ccsilver.com/supplies/tools/tools2.html) to make small holes in granite. They should work on ear bones as well.

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**Author:** ![astro](https://avatars.discourse-cdn.com/v4/letter/a/9dc877/32.png) [@astro](https://boards.straightdope.com/u/astro)\
**Post date:** [August 21, 2004, 3:44pm UTC](https://boards.straightdope.com/t/how-do-i-drill-something-that-is-very-hard-and-brittle/260850/3 "2004-08-21T15:44:13Z")

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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.

See

[Drilling rocks](http://www.rocks4u.com/drillrock.htm)

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**Author:** ![enipla](https://avatars.discourse-cdn.com/v4/letter/e/54ee81/32.png) [@enipla](https://boards.straightdope.com/u/enipla)\
**Post date:** [August 21, 2004, 4:10pm UTC](https://boards.straightdope.com/t/how-do-i-drill-something-that-is-very-hard-and-brittle/260850/4 "2004-08-21T16:10:29Z")

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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.

[http://www.dremel.com/html/home\_fr.html](http://www.dremel.com/html/home_fr.html)

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**Author:** ![enipla](https://avatars.discourse-cdn.com/v4/letter/e/54ee81/32.png) [@enipla](https://boards.straightdope.com/u/enipla)\
**Post date:** [August 21, 2004, 4:13pm UTC](https://boards.straightdope.com/t/how-do-i-drill-something-that-is-very-hard-and-brittle/260850/5 "2004-08-21T16:13:18Z")

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And…

Fish ear bones. Huh.

I learn something new here every day.

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**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\
**Post date:** [August 21, 2004, 5:01pm UTC](https://boards.straightdope.com/t/how-do-i-drill-something-that-is-very-hard-and-brittle/260850/6 "2004-08-21T17:01:24Z")

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> [@enipla](#):
>
> Have you tried a Dremel drill. The little hand held jobs that spin at 20-30,000 rpm.

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.

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**Author:** ![spingears](https://avatars.discourse-cdn.com/v4/letter/s/ebca7d/32.png) [@spingears](https://boards.straightdope.com/u/spingears)\
**Post date:** [August 21, 2004, 5:32pm UTC](https://boards.straightdope.com/t/how-do-i-drill-something-that-is-very-hard-and-brittle/260850/7 "2004-08-21T17:32:49Z")

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> [@Squink](#):
>
> I’ve used a [0.75 mm diamond drill bit](http://www.ccsilver.com/supplies/tools/tools2.html) to make small holes in granite. They should work on ear bones as well.

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.