There are mostly two reasons why a drill breaks. Deflected breakage is caused by the radial force, the drill bit is broken at the end of flute. Twisted breakage is caused by the large torque, the drill bit is normally broken at the middle of the flute.

Why do my drill bits keep going blunt?

It's likely you're just heating up the bits and ruining them quickly. If you're setting the dial to hammer and exerting decent pressure, it's the drill that's the problem.

How do you tighten a chuck on a drill?

Insert the drill bit into the drill chuck. Tighten the drill chuck only by hand until it clicks several times. Rotate the chuck back the opposite way, until you hear and feel one, single click. Once you hear and feel the last click, the drill bit is locked securely into place.