[Dick Linn]

One thing I thought we'd do is to drill through one of the flats on the aluminum coupler (without the left-hand screw in place) and 1/2 way through the threaded drill shaft, then use a roll pin to help prevent it from unscrewing. If done correctly, it would not significantly weaken the threaded part on the drill, yet would serve as a backup to the left-hand screw and the friction of the aluminum shaft adapter threads. I hate to think of using a serious type of Lock-Tite in case I have to get that puppy apart.