I just drilled a 40G Breeder last night. I used a 64mm (for heavy duty 1 1/2" Bulkheads) diamond drill bit. It took a total of about 20 minutes and went very well.
I used a 18V battery powered drill. Here is what I did.
First I decided where to put the wholes and take a piece of cardboard down on the glass. I drilled through the cardboard, which acts like a guide. After you have etched the glass enough so the bit will easily go back into the same spot (1/8" or so) it is fairly easy. Also after you have etched the glass you can take the cardboard off. Make sure you save the cardboard for the next whole. Just turn the cardboard to the downside of the hole #1 for the exact mirror location for hole #2.
Make sure you do not push at all on the drill, use the weight of the drill to put very light pressure on the bit. While you are drilling you need someone with a turkey baster to dribble water on and around the bit. You will hear the noise and know when you need to add water. If the noise is annoying or hurting your ears you need water.
You will eventually drill through and see water dripping on the inside of your tank. At this point, you need to put a towel or something soft under where the whole is so the cirlcle of glass you cut does not hit and break the tank. OK, now that you are seing dripping you need to go real slow (not the bit speed). You actually need to support the drill and only allow about 1/2 the weight of the drill press against the cut. Eventually it will cut through.
Couple of notes.
1. I used a new battery for each whole, you want to run the bit at full speed
2. Wear safety goggles
3. Do NOT use the hammer setting on the drill :razz:
4. Did I say wear safety goggles??
That is really it, just remember, take things very slow and deliberate.
Good Luck,
JBW
