1. The blade of the screwdriver must be ground correctly, and the two sides of the blade should be as parallel as possible. If the blade is tapered, the blade can easily slip out of the screw slot when turning the screwdriver.
2. Do not grind the head of the screwdriver too thin, or grind it into a shape other than square.
3. Be very careful when grinding the screwdriver on the grinding wheel, it will overheat and soften the edge of the screwdriver. Wear goggles when grinding.
