1) The diameter of the drill should not exceed the allowable diameter of the drill.
2) The drill bit must be clamped with a key, not allowed to hit the drill chuck with other tools.
3) When drilling force is not allowed too much, to prevent the motor overload. If you find that speed reduction, should immediately cut off the power check.
4) sporadic pieces must be firmly fixed in the fixture.
5) Do not wear gloves.