All lawn mower blades need to be sharpened at regular intervals to keep your grass healthy and looking great. For lawn mowers mowing regular sized lawns, the blade should be sharpened at the beginning of each season. If blades are not sharpened, your grass will begin to take on a shredded look due to the dull blade ripping the grass. Disease and fungus can also enter your grass through these torn ends. Sharpening your mower blade can be done with just a few common household tools.
Remove the gas from the lawn mower by either running it out of gas or using a siphon hose to drain the gas into a gas can.
Disconnect the spark plug wire from the back of the spark plug. It should pull right off the back of the spark plug.
Lay the mower down on either side and examine the mower blade. Notice that the blade is connected to the lawn mower with a single bolt in the middle.
Slide an adjustable wrench on to the bolt and loosen it by turning it counterclockwise. You may need to hold on to the blade with your other gloved hand to get enough torque to loosen the bolt.
Loosen the bolt all the way and remove it. Pull the lawn mower blade off the lawn mower.
Scrub the blade thoroughly with steel wool or a wire brush to remove any rust and caked on plant material.
Clamp the blade down in the table vise. Examine both ends of the blade. You should see that each end is beveled down to a sharp edge. You will need to maintain this same angle of this bevel when sharpening.
Take your metal file and align it parallel to one beveled edge. With smooth motions, push the file along the entire length of the beveled edge. Repeat this until the edge is smooth and shiny. Repeat this process on the edge that is on other side of the blade.
Remove the mower blade from the vise and balance it in the middle with your finger. It should sit perfectly level. If not, you will need to file off more material on the side that dips down.
Reattach the blade to the lawn mower and tighten the bolt with your adjustable wrench. Set the mower back upright, attach the spark plug wire and fill it with gas. You are now ready to cut grass again.