Tips for drilling glass?

[Buddabing]

Hello,

My wife is making some Christmas decorations.

There are these hollow glass cubes which are about 8" by 8" by 4" with the glass maybe 1/4" thick. What she wants to do is to drill a hole in the cube and thread a string of tree lights into the hole, so that the cube will light up when the string is plugged in. Then the outside is wrapped up so that the whole thing looks like a lit up Christmas present.

She got a cheap drill and a "glass cutting" bit. Her cousin was visiting a couple of weeks ago and he drilled the first one and it worked fine. She then tried to drill another one and she broke it.

What does she need to do for drilling the glass?

TIA,
Buddabing

[ChadTower]

First guess is less pressure.  If she presses too hard it will shatter the glass... just let the speed of the bit do it slowly with very little surface pressure.  Almost like etching.

[kelemvor]

And I'd guess that the faster the bit spins the lesser chance of the thing splitting...  But I'm just guessing.  But definitely don't push much, just let the bit do the work.

[_) (V) (-)]

I once watched a guy drill a hole into a big assed picture window using a high speed dremel tool and cone shaped bit. (was a grey stone type, sorry I don't know the technical name for it) 

Anyway, he was using a very light touch and spraying the thing with regular tap water from a squirt bottle. I'm guessing it was to cool the bit and wash away debris.

Worked slick.

[emerica]

its important to keep the bit cool with water or whatever. Heat will cause chips or clams in the glass.

Also try not to stop the bit while drilling the glass, that will cause the glass to break also.

[Fluffy the Bear]

Find a plan-B alternative to drilling your glass

Drilling holes in glass is just about the last thing you want to do with your glass

It might break today

It might break tommorrow

Real good chance it's gonna break eventually and that nice hole will be the culprit

[DrewKaree]

I know this is late and she's prolly found some solution, but for next year, tell her to think about this:

My mother-in-law took a few glass blocks, the kind that you would use for a bathroom or basement window for privacy, and simply stuck a string of 'em in, then wrapped it up to look like a present.  IIRC, she picked up the type that were open on one side, and you simply put that side towards your outlet.