On 4/15/20 12:22 PM, Arthur Conan Doyle wrote:
wrote:

I am trying drill some holes in glass tile to allow the screws from a GFI receptical cover to seat properly. Purchased a 1/4" ceramic and glass bit and drilled a test hole in an extra tile. All went well.
Left it on the workbench and returned 1/2 hour later to find the corner had cracked off.
What went wrong ? Why would it do that ?

Thermal stress as the tile cooled? Not sure if you are referring to an interior
cutout corner, or one of the exterior corners, but if it was an interior corner,
you should be drilling all four corners and not have any 90 degree transitions.




Maybe just attach the plate to the wall with a little RTV.

It will hold just fine and would be easy to remove.