These aren't quite as torquey as the other types (but it's RPM which matters most anyway for drilling). Upside is they don't have any hoses or cables to get tangled with and don't run at mains voltages (check if waterproof before getting too cocky).

• Grind through shafts or nuts.

• Grind off heads.

• Grind away paint and corrosion.

• Grind flats onto shafts or heads.

• Torque is handy, RPM is the key.

• 10,000 RPM or better.

• Always wear eye protection

• Always wear hearing protection

• Consider impact protecting gloves