Makita drills chucks are designed to be tightened and removed by hand, without the need for a key. This is true of most cordless drills. Although it is not necessary to remove the chuck of your Makita drill too often, chucks do become worn out and faulty over time and may need to be replaced. Rather than bringing your Makita drill into a repair shop, you can remove the chuck yourself in a few easy steps.
Take out any drill bit still mounted in the drill's chuck. Using a Phillips screwdriver, remove the screw inside of the chuck. The screw is reverse-thread, meaning it will need to be unscrewed with a clockwise motion.
Secure the drill into a vice with the chuck facing upward. Although the drill body is pretty tough, take care not to fasten the vice too tightly.
Insert a 1/2-inch Allen wrench into the chuck, as you would a drill bit. This is the largest Allen wrench that will fit into a Makita drill chuck. Tighten the chuck by hand to secure the wrench into place.
Hit the protruding end of the Allen wrench gently with a hammer, counterclockwise, to loosen the chuck. Once loose, the chuck can now be removed easily by hand.