Cracked tank after drilling

[thereefcanada]

Ok this may be a stupid question. I drilled my 40 gallon breeder on the back. All the holes were drilled and I was getting ready to mask off the back when I dropped my phone on the tank and the a crack formed from one of holes right to the top of the tank. Was this just a problem waiting to happen aka weak tank or bad drilling or was it only the drop that caused it. I have a new tank on order now and I'm a little nervous about drilling it now. Again may be a stupid question but maybe if I didn't drop the phone on it and filled it up it may have failed full of water.

 

[fishgate]

People drill these all time. Accidents happen. Drill away on the next one!

 

[uncleof6]

Where the holes less than 1.5x the diameter of the hole (to center) below the top edge of the glass? If not, that is why it broke.

It could also easily have been a stress fracture that opened up on the impact of the phone. Stress fractures are micro scopic cracks that appear around holes drilled in the glass, due to stress caused by too much pressure and chipping. Glass hole saws do not cut through the glass, they grind through the glass, so pressure is a bad thing.

In either of the above cases, the glass probably would have broken eventually anyway. If you are nervous about it, take it to a glass fab shop and have the new tank drilled professionally.

Most DIY hole drillers use cheap saws and poor technique. You need a good hole saw, and a guide/jig to keep the saw from moving/jumping. Holes in glass should be started from one side, finished from the other, then the hole should be "polished" and chamfered to relieve the stress. No sharp edges and no chipping.

 

[thereefcanada]

Cracked tank after drilling

I made a jig out of wood to keep the drill from jumping around seemed to work pretty well, but I think I will take the tank to the glass shop next time so I don't waste a bunch more money. I already took the broken tank to the dump, I should have kept it and practiced on the other side. Thanks for the replies and I'm glad it broke then rather than when it was full of water