This is my first experience with a hole saw. Not sure if this is normal for hole saws, but it was hard to get this thing to work properly. First, if you turn the saw clockwise, it just spins off the drill bit and falls down. The damn thing also slipped out of the drill and had to be tightened several times. I finally managed to get it to work properly. The trick is to use it counterclockwise (at full speed). This way the blade doesn't slip off the drill bit and also the blades are positioned to