drilling my tank...again

so i tried drilling my 40b with my dad 2 weeks ago and well... it broke. i got 95% there to the point where i could see though it a little then my dad started moving the drill in circles, i said no, No NO!! then boom.

now i got a new tank and i already scribed the circles a little so they dont just when i drill. they holes are 3" apart and it 1/4 or 3/8 glass i believe.
Any tips for this?

 

You might want them a bit further apart than 3"...just my opinion.

 

how far would you say?

 

The general rule of thumb for spacing is 1.5 times the diameter of the hole you are drilling.
Forgot to ask what size bulkhead though..and your glass is thinner so I'd go further apart just for safety's sake.

 

im using two 1" bulkheads so 1x1.5=1.5" or is it 2x1.5=3"? if it comes out to 3" then add 1-1.5" just for safty

 

get a spary bottle full of water and constantly spray while you are drilling if you are not doing that already. also what hole saw did you get to do this with?

 

diamond tipped one, i ran a garden hose over it the first time

 

another thing that helped me was to clamp a piece of wood behind the hole you are drilling so you can cut into that and it will keep the thin final layer of glass from shattering or snagging your bit again.

 

it will drill through wood too?

 

No it will just hold the glass in place. Its what I have done too. It prevents chip out. Your diamond bit wont cut the wood at all..