Why does my chuck keep loosening - Dewalt 18v Battery Hammer Drill Dcd950 Dc925

To remove the chuck from a Wilmar KFF-6 drill, follow these steps:

1. Turn off and unplug the drill.
2. Locate the chuck key that came with the drill.
3. Insert the key into the chuck and turn it counterclockwise to loosen the jaws of the chuck.
4. Remove the chuck key from the chuck.
5. Grasp the chuck with one hand and hold the handle of the drill with the other hand.
6. Turn the chuck counterclockwise to remove it from the spindle.

If the chuck is stuck and won't loosen, you may need to apply some penetrating oil to the threads and let it sit for a few minutes before attempting to remove the chuck again. You can also try using a rubber mallet to gently tap the chuck counterclockwise to loosen it.

There is a torx headed screw inside the chuck that is reverse thread (Right hand to loosen) - remove that then the chuck will spin off standard thread (Left hand loosen)
Most of the time I chuck a 1/2" allen wrench into the chuck, mount the drill in a vise, and strike the wrench with a hammer to get the chuck off

if you are using a normal 3 jaw chuck on the drill , that is normal when hammering
the vibrations loosen of the chuck
a method to stop it is to ensure the chuck is tight and keep pulling the drill out of the hole to remove the grit that jams the bit

as long as the chuck is used for a hammer drill and the thread size is exact yes it will. I believe the thread is 1/2-20 and also make sure the chuck has a hole in the center for the reversing screw to keep it from loosening up. Let me know if you need more assistance. The thread size is usually stamped on the side of the chuck. Makita sometimes used a metric thread.

Try shooting some WD-40 lubricant into the 'chuck' and let it sit for awhile, then rotate the outer part of the chuck CCW to loosen the 'jaws'. If the chuck is a keyless type, just hold the chuck and turn the reversing switch to 'reverse', then gently apply power to the trigger--that should open the chuck jaws. You will likely find that a leather glove on the hand holding the chuck will help prevent a burned hand if you lose your grip. If it is a keyed--type chuck (there will be ring of gear teeth on the front edge of the chuck), then a key with a small gear near one end is required to turn the chuck open (turn the key CCW). Hope this helps!

There is a screw in the bottom of the inside of the chuck. You have to loosen it with a quick, sudden turn while keeping pressure( as the chuck wants to turn with it). Putting the drill in its slowest gear helps increase resistance some.

Bit of a nuisance, really but what can you do:)
Regards, Farmerbear at FixYa.com

When the drill bit on a hammer drill keeps loosening up one of two things is happening. 1. The chuck is worn out and needs to be replaced. 2. The chuck is not tight enough before you start drilling. If you have the style of chuck that requires a key do not be bashful about using maximum force to tighten the chuck and move the chuck key from hole to hole and tighten it in each position. Joe

If you say that the chuck can not be tighten only, then I would say that the left thread screw that keeps the chuck to the tool have become unloosen and can not allow the chuck to be tighten. The remedy for that is to unloosen the chuck as much as you can, then tight the left thread screw but rotating it left till the bottom and then the chuck will work. All the above if the chuck can not be tighten...

If this is a cordless drill open chuck jaws and remove the retaining screw (LH trheads), switch the clutch to drill only and shift gear selector to low. Insert a bent handle allen wrench about the same size as chuck (to keep from flexing) put chuck on workbench or block of wood and have the wrench about 30 degrees and strike the key counterclockwise to remove. You might have to hit a couple times but usually they will loosen up quickly. To install just reverse above. Let me know if I can help further.
Dave

To remove the chuck on your drill follow the instructions for the type of drill chuck you have:
Instructions for removing a keyed chuck
Most reversing drills have a left hand threaded screw located inside the bottom of the chuck.
1.) If the unit has this screw place the chuck key, with the chuck facing toward you, into one of the holes on the right side of the chuck. Strike the key in a clockwise direction with a wooden mallet or similar object. This will loosen the screw inside the chuck.
2.) Open chuck jaws fully. Insert screwdriver into the bottom of the chuck to engage screw head. Remove screw by turning clockwise this is a left-hand screw.
3.) With the chuck facing toward you place the key into one of the holes on the left side of the chuck. Using a wooden mallet or similar object, strike the key sharply in a counter-clockwise direction. This will loosen the chuck so that it may be unscrewed by hand.
There is no way to stop the motor from turning.
It may require several attempts to loosen the chuck
Instructions for removing a keyless chuck
Most reversing drills have a left hand threaded screw located inside the bottom of the chuck.
1.) If the unit has this screw open chuck jaws fully. Insert screwdriver into the bottom of the chuck to engage screw head. Remove screw by turning clockwise this is a left-hand screw.
2.) Insert the short end of a 1/4" or larger hex Allen wrench into the chuck and tighten. Facing the tool strike the long end of the hex wrench sharply counter clockwise as it is a standard right hand thread. This will loosen the chuck so that it may be unscrewed by hand.
There is no way to stop the motor from turning.
It may require several attempts to loosen the chuck