I have this friend with a probelm..... really....:-)
He has trouble with the keyless chucks on his drills (one cordless, one corded) having the bits slip.
(Craftsman & Black & Decker)
He has tried hand tightening but, the bit still slips. Two drills... multiple bits/
Could it be technique? Foreighn material on the chuck jaws?
Suggestions please.