On Wed, 15 Apr 2020 05:55:16 -0700 (PDT), 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 ?
Thanks

Do you have kids? Sometimes they get curious and things just sort of
happen.