Many mower parts must work together to properly cut a lawn. One of the most important parts of any mower is the cutting blade. Featuring a sharpened bevel cutting edge on opposite sides of the blade, mower blades spin at a high rate of speed to clip the grass as the mower moves. Dull blades tear the grass, leaving it susceptible to disease. Sharpening a blade is a necessary part of routine maintenance and can be done with a bench grinder.
Position the mower on a flat and level surface so it will not roll while you are working with the cutting blades. Put on a pair of leather work gloves. Place a piece of wood under the cutting deck and against the side. Turn the blade to wedge the wood in place and prevent the blade from turning.
Loosen and remove the bolt connecting the blade to the spindle of the mower, using the appropriately sized wrench. Remove the bolt and washer from the hole in the center of the blade.
Move any equipment or objects from the area around or in front of the bench grinder to provide adequate working space. Turn on the bench grinder and allow it to come up to operating speed.
Put on a pair of safety glasses. Hold the mower blade firmly so that the beveled edge on one end is easily accessible. Turn the beveled edge of the cutting blade to a 40-degree angle. Move the cutting edge completely across the bench grinder. Remove only as much metal from the edge as needed for sharpening.
Turn the blade around so the cutting edge on the opposite end is accessible. Repeat the sharpening process.
Insert a pencil through the hole in the blade, and check the blade balance. Observe the blade to see if it tilts to one side or the other. Remove small amounts of metal from the heavy side by moving that edge across the bench grinder.
Place the bolt and washer back through the hole in the sharpened mower blade. Secure the blade assembly to the mower spindle. Tighten the bolt with the wrench.