Take the bit out and reset it before assuming the chuck is bad. A bit that is crooked, oily, damaged or not fully tightened can slip even when the drill is fine.
Reset the bit from scratch
- Remove the battery if you are working around the chuck.
- Open the chuck enough to remove the bit.
- Wipe obvious oil or debris from the bit shank.
- Insert the bit straight and center it between the jaws.
- Tighten the chuck securely by hand.
The DCD771 uses a single-sleeve ratcheting chuck. DEWALT describes it as providing tight bit gripping strength.
Do not use the motor to tighten the chuck by hand
A bad habit is to hold the chuck sleeve and tap the trigger to tighten it. That puts your hand around a powered rotating assembly. Tighten the keyless chuck the way your manual instructs instead.
If one bit slips, suspect the bit
Small round bits can be easy to clamp off-center. Damaged shanks can be harder for the jaws to grip. If one bit is troublesome and five others work, the drill is giving you a clue.
If every bit slips, inspect the chuck
Watch the jaws as you open and close the chuck. They should move together. If the chuck will not tighten securely, visibly runs crooked with several good bits, or loosens repeatedly during ordinary work, the chuck may need service or replacement.
Do not buy a replacement chuck because the diameter looks right in a photo. Chuck mounting and model compatibility vary. Match the exact drill model and service information before ordering.
Bit slipping vs. bit wobbling
These look similar but are not identical. A slipping bit actually rotates inside the chuck or works loose. A wobbling bit may be clamped off-center, bent or poorly made. Open the chuck, reset the bit and watch it spin before you assume the chuck is failing.
Do not over-tighten your way past damage
If the chuck jaws are damaged or the bit shank is badly chewed up, more hand force may not solve the problem. Repeatedly forcing the chuck can make a repair harder. Stop and inspect the parts.
When a replacement chuck becomes reasonable
If several straight, undamaged bits slip after proper tightening, the jaws do not move evenly, or the chuck will not stay tight during normal work, service or replacement becomes a reasonable next step. At that point, use the drill’s exact model and type number when searching for parts.