"Mark M" wrote in message
I use my hand and not a key to tighten the chuck. On occasions like
you're describing, I've always been successful in placing the open chuck
over the bit, using my right hand to trigger the motor and the left to
close the chuck on the bit. Once it engages, a couple minor wiggles will
loosen the rotating bit enough to ease its removal.

It's a keyless chuck in a cordless drill. The problem is that the drill's
heaviest part is off center ( the battery) so one little flinch and the
drill bit breaks off. The suggestion to use a nail with the end sharpened
sounds like a decent solution so I'll have to try that one out.