Different type of shaft key (Dutch Key)

[tonyfoale]

I have often used this technique but I never knew that it had its own name, Dutch Key.
In order to ensure a balanced load between shaft and housing I often use 3 screws. Of course it also increases the torque capacity. Instead of the obvious 120 deg even spacing I always offset one screw so that it is say 110 and 130 deg from the other two. This ensures that if it has been disassembled it can only go back together as it was.