I don't get it what are u trying to do ? I just put a new glass panel in my 40 because is was cheaper to just buy a piece of glass and silicone . Than a whole new 40 drilled with a new over flow I got the tank free and repaired it but let me tell you it was a pain in the butt to get the glass out without cracking it . Are you trying to make it rimless ? All I can say is make sure u take your time and get brand new flexi razor blades .. Again take your time .