Very good product, excellent for amateur uses, but I wonder if my drill is not a defect chuck because I have trouble tightening the forests. This is the 1st time I see this problem with a drill! They turn indeed quite easily in a vacuum when it forces a little, whatever the diameter. This is quite unpleasant! I hesitate to change the chuck, as if they are all like that, it's not worth it. He has found someone that?