On Aug 12, 8:18*am, Edge wrote:
I have a Craftsman 19.2 volt drill with a half inch chuck. Many times,
especially while pressing hard into the material being drilled, the
bit slips. No matter how much I tighten the chuck, the bit continues
to slip. Other than replacing the chuck, which isn't worth it, what
can be done? Is there a spray of some sort or something else to
provide a better grip on the bit.

Why are you pressing down so hard?
Try using a little cutting oil
Use sharp bits,
If you are drilling a large hole drill a small pilot hole first.
Still having problems, you have a bad chuck.