Chucked a blade in the roto zip this evening. I know I got it good and tight. When I turned it on, it bent, flew out and hit me square in the face. Took about 2 milliseconds! Luck was with me though as I had just put my dust mask on. You can see where it hit "AOSAFETY". Every once in a while these tools make you remember who is really in charge. I put it all down and went in the house, done for the evening.