Drilling hole in glass?

[Peter Peng]

Looking to drill a hole in the bottom of a 33g long tank.
In the past, I've used a blowtorch and slowly melted the glass in a small tank and very slowly letting it cool and keep doing it untill it reaches the size I want to install the bulkhead.

Is this a good idea or a really risky move that ruin the tank?
From my experience, as long as you keep temperature stable and give it time to cool down, everything should be ok...

any suggestions?