While it might not seem like it, using your lawnmower does wear down the blade over time. Repeatedly hitting those bits of grass eventually dulls the edge, as it would any blade, and leaves it less able to make clean cuts in your grass. The cleaner the cut on grass, the better your lawn will look. Ragged cut ends on grass blades causes them to brown at the edges and makes the grass look as though it were dying.Sharpening a lawnmower blade yourself is not as difficult as you would think. The process is simple, but will require you to put in a bit of elbow grease. You'll need the following tools:Vise or Clamp8 Inch Double Cut File400 Grit SandpaperSmall Block of WoodThe first step is to remove the lawnmower blade of course.Do not turn the lawnmower over. It will flood the engine and possibly cause fluids to leakYou may need a friend to help you take the blade off. One removed, you'll need to secure the blade to a surface using a vise or clamps. Once secure, find the blade portion of the metal. It should have portions filed away near the ends of the blade that look like a crude knife. This slope that has the cutting edge is known as the grind. Take the file and rest it against the grind so that it lays flat. You'll want to remove metal at the same angle it is was when it was made. Stroke the file towards the blade and away from the center. You want to evenly file the blade and not remove metal in only one place. It will look like a diagonally motion on your part. Continue to file until the entire slope of the blade section is shiny. Once that is done, take the sandpaper and attach it to the wood using either glue or staples. You are going to use the same motion on the opposite flat side of the blade portion, but only just enough to remove the metal burr you have developed from filing. After the burr had been removed, take the block of wood and rub the wood against the sharp portion of the blade just once. This will remove the smaller burr developed from sanding. This should leave you with a very sharp blade that will last you through another cutting season.