Each electric drill has a built-in, mechanical device called a "chuck," which secures drill bits and attachments to the front end of the drill. Many cordless drills have three-jaw chucks, which require less effort to quickly remove and replace drill bits. Drill chucks should be cleaned and oiled on a regular basis to avoid significant damage to the mechanical parts inside. This requires that you partially disassemble the chuck.
Remove any bit or attachment from the chuck. To do this, press on the direction button near the trigger and set it in reverse. Grasp the chuck firmly in one hand and pull the trigger to loosen the bit from the chuck. If you are using a standard electric drill, loosen the chuck with the key that came with the drill. Place the key into the chuck and turn the key counterclockwise.
Press the locking button above the drill's trigger to disable the trigger. Unplug or remove the drill's battery. Insert an Allen wrench into the open jaws of the drill until it grabs the screw inside the drill attaching the chuck to the drill's spindle. Turn the screw clockwise to loosen and remove the screw (all drill manufacturers use a left-handed screw to attach chuck to the spindle).
Replace the drill's battery or reconnect the drill's power cord to the nearest electrical socket. Grip the chuck with a large wrench or vice grip. Unlock the drill's trigger, and make sure the trigger is still set in reverse. Squeeze the trigger to disengage the chuck from the drill's spindle.
Disable the trigger and remove the drill's battery or disconnect the power cord. Turn the chuck counterclockwise with your hand until the chuck is completely removed from the drill. This will give you access to the inside of the chuck for cleaning and lubrication.