How To Drilling Drainage Holes in Ceramic Pots?

I have some small enameled ceramic pots that were designed as in-door pots as they have no drainage holes. I'd like to use them as herb pots and put them outside in the summer months.
I have a Dremel 4000 with various glass and tile cutting bits, carbide bits and diamond-dipped bits. But I'm not sure what's best to go for? Something diamond-dipped or not? Something blunt or pointed? Something small and thin or a specific tile/glass hole cutter?
I realize how hard enameled ceramic is. The hardest thing to date I've drilled through is stone (for jewellery). Are there any similarities I could use?
Any experience and tips would be appreciated : )
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Thanks Edd. Yes, I was planning on using masking tape too, and water as a cooler.
Do you know if I should lean the bit into the ceramic or go straight down from the start?
use a thin drill bit, then work up to the size hole you need.
Less likely to crack in my experience.
Thanks Both : )
Leaning the bit in isn't meant to create any extra force, merely to create a dip in the ceramic for the bit to sit in. The idea being to lessen any vibration caused and thus lessen the chance of cracking. But I suppose if I was to use a pointed bit then this shouldn't be too much of a worry.
I do have tapered bits that I have used, for other materials, to gradually enlarge a hole with very good success. Sounds a good idea.
Hi Blue Dragon. My wife makes ceramics, some of them enamelled. Many people don't realize that the enamel on ceramics objects (sometimes called "glaze") is ... glass. So if you need to drill holes into it, you have to use a specific bit for glass. Have a look at this site: http://www.drillglass.com/hehiforbe.html. Of course the masking tape is a good idea to prevent your bit from slipping.
Hi Papi Jo : )
I do have specific bits for drilling through glass. They're extremely finely abrasive, meaning that the glass is closer to being polished down rather than grinded (as with a diamond-tiped bit). They're used for engraving into glass such as vases etc, but the pointed ones, although it can take a while, can be used to create holes too.
Not sure they'd be up for getting through ceramic though? They're not designed for such hard materials really. Maybe use a rounded one to get through the glaze before moving on to a tougher masonry bit?
Those are the bits I would use: http://www.amazon.com/Vermont-American-13310-4-Piece-Glass/dp/B000ETWIKM
Yes, I have versions of those too : )