1.Tighten the bits when screw on. 2.When the bit lower down to the bottom , Should give a soft pressure, slow drilling .After a drilling 0.2m-0.3m with appropriate pump, then give the conventional drilling. 3.Drilling could not be without water, if not fear the normal vibration sound or drill too slow, lift the drill to check without delay. 4.When drill jammed, withdraw first, should not to force the rig start. 5.Drill could not without water, to ensure that the bit will be too hot. 6.Use the bits in right order , big size first, then small one . 30*40*45 cm 50kg