1. Twist drill is a common drilling tool in machining. Before grinding the drill bit, put the main cutting edge of the drill bit and the surface of the grinding wheel on a horizontal plane.

2. The axis of the drill bit should be inclined at an angle of 60 degrees with the surface of the grinding wheel. Pay attention to the relative horizontal position and angular position of the drill bit before grinding.

3. Contact the grinding wheel from the cutting edge of the drill bit, and then slowly grind it down along the whole side. Pay attention to the uniformity of spark and the cooling of drill bit.

4. The cutting edge of the drill should swing up and down, and the drill tail should not be tilted. The hand holding the front of the drill should swing the drill evenly on the surface of the grinding wheel, but the hand holding the handle should not swing.