Chuck undoes when drill is in reverse - Dewalt DC925 Cordless Drill

open the chuck jaws right up
down the center of the chuck you will see either a philips screw head or a hex head for allen key
hold the shaft at the base of the chuck to stop it from turning and undo the screw in the chuck in a right hand direction ( it is a left hand thread) when you have that out , still holding the shaft turn the chuck in the left hand direction ( normal thread ) and screw the chuck off
to assist in undoing the chuck do it up so that the jaws come out a bit
place something between the 3 jaws to act as a lever or use an allen key in the chuck done it tight and use that as a lever to undo the chuck
the secret is the lh thread screw in side the chuck which stops it from undoing when the drill is in reverse

or if there is no screw in bottom,then it is a screw on chuck. put chuck bit into chuck as if you were tightening it, then hit it with a mallet to remove(counterclockwise)

if it is a reversible drill , open the chuck jaws open all the way and at the bottom of the chuck inside you will find either a phillips screw or a allen key screw
turn that screw in a clockwise direction as it is a lh thread and is a locking screw to stop the chuck coming off when used in reverse mode

hold the shaft at the base of the chuck and using something like vice grips on the chuck( section in from of the key teeth) grip firmly and hit hard with a hammer on the grips to undo normally

open the chuck up as wide as possible . At the bottom of the chuck you will see a Phillips headed screw . AS this is a left handed thread screw it will you to turn it as it screwing it in to undo it. This is a lock screw that stops the chick undoing when in the reverse direction mode Once it is out then use the key in the hole and teeth and hit the key sideways sharply to unscrew the chuck of the drive shaft. Replacement is the reverse procedure. Do not loose the screw as replacement part is not available unless you have a junked drill that you can get it from

if its a reversible drill,you open the jaws wide,and undo the left hand threaded screw inside the chuck,then put the the chuck tool in,and use that to unscrew chuck off the thread,right hand thread

If you open the chuck as far as it will go and look inside you may see the head of a screw, especially if the drill is reversible. So undo the screw and then you should be able to unscrew the chuck. But I am not sure if it will be easy to unscrew. With a keyed chuck you use the key and a hammer to unscrew the chuck.

If you man changing the chuck, take out any drill bits and look down into the chuck. You will see a screw holding it on. On many drills this screw has a reverse thread so it loosens in the opposite way to regular screws. You have to undo this screw to remove the chuck, then fit a new one of the same spec or one suitable for the drill and reassemble in reverse order.

Put the bit in a vise and try hittig the reverse button.If that does not work the tap the three lock tabs in the end of the chuck with a punch and you should be able to undo the chuck.

This drill has a keyless chuck. Put your bit in the chuck and hold the collar of the chuck while pressing the trigger in the forward position. To undo the chuck do this in reverse. You can also hand tighten the keyless chuck if you prefer. I have a 1/4' adapter that I keep in my drill so I can change bits quickly.

hi this should be reletively easy hold the end black bit with the sivler bit holde coming out not the black bit next to the yellow case on drill you hold the black part thats at end of drill by where the bit goes into not the black bit near the trigger hope i explain this ok.
Hold this bit tight then put drill in reverse then press trigger a couple of times it might be tight but shouldnt be that tight it wont undo.
1 put in reverse
2 hold black plastic piece near where drill bit goes into
3 press trigger few times
4 this should undo it allowing you to put a bit in
make sure its in reverse else you will just tighten it up more let me know if you need further assistance ok