Turn on the drill first, then cut, and when finished, exits first and then turn offs the drill When cutting, the cutting edges of cutter holder must be keep perpendicular to the workpiece being cut to cutter from breakings due to hard deformation cutter holder replacement: Rotate the clamping caps counterclockwise and replace it with a new cutter holder Regularly add oil to the cutting edges of cutter, especially when cutting aluminum plates cutter holder replacement: Open the protective covers, remove the antiloosening nut, loosen the set screw, use pliers to pull out cutter holder, reinstall cutter holder, and tighten the screw, Manufacturer: YINGhhh