Now isn't this coincidence, cutting and installing 2 x 2 drop-in ceiling tiles is all I did today and will do tomorrow. I learned years back NOT to use any power tools on these as it just makes to big a mess. I use the framing square and razor knife method, and as posted, change blades about every sixth tile or so. Me-I also like to spray the edges with KILZ in the spray can to sort of bond the fibrous cut edge and to give it some whitish color. Some of you may understand this-one reason I am having to replace these tiles in a business is that they are sagging very bad, not discolored at all, just sagging. Why, I know you asked. This is a house built in 1898 and had acoustical tile ceiling put in some twenty years or so ago when it became a law office. When I pulled out a good tile to see why the tiles were sagging, there lying on top of the tiles was the plaster from the original ceiling, about two feet above the tiles. The lath boards are still in good shape but the plaster has let go and fallen onto these ceiling tiles which cannot support the weight. I bet I removed a couple of hundred pounds of this broken plaster today. It's a shame, I'd rather see good finished plaster than those ceiling tiles any day. Thanks, David