Not sure if this has been posted yet I think it's real important to know about. Concerns the safety of your home and family.
http://www.youtube.com/watch?v=hr23tpWX8lM
http://www.youtube.com/watch?v=hr23tpWX8lM
If you hit the key too hard yes you can ruin it.
If you do a crappy job of filing the key down you can get to steep of an edge too and when the key is inserted you won't be able to remove it...
thanx I didn't want to try it on my door and have no lock