When drilling with a hole saw (the kind of bit you use to cut big holes for door knobs) make sure to attach the outrigger handle to your drill. This gives you extra leverage in cases where the hole saw catches. If the saw catches it creates a *lot* of torque since the saw is so big. This in turn can cause the drill to snap violently causing all sorts of injuries. That's why you need the outrigger handle, it gives you extra leverage to withstand the higher torque.