Electric lawn mowers are just like gas-powered lawn mowers in that they have a single blade that rotates around a shaft to cut your grass. The blade slices through the grass at a high rate of speed and shears off the grass. Since only a few inches on each end of the actual blade act as the cutting surface, your lawn mower blade will cut through a very high number of grass blades over the course of the season. This will slowly dull the blade and it will either need to be replaced or sharpened to keep your grass healthy. Sharpening your electric mower blades is not complicated and can allow you to get many years of use out of one blade.
Remove all power to the lawn mower by unplugging it. Lay the mower down on its side.
Find the bolt that attaches the mower blade to the shaft. It is in the center of the blade.
Slide an adjustable wrench on the bolt. Turn it counterclockwise to loosen it. Continue to turn it until you can completely remove the bolt.
Take off the blade and put it in your table vise. Brush it with a steel brush or rub it with steel wool to remove any rust and caked-on grass debris.
Examine each cutting surface of the blade. You will need to follow the existing angle of the cutting surface when sharpening the blade.
Position your file parallel to the cutting surface and with smooth motions, push it along the entire cutting surface. Keep filing the cutting edge until it is smooth, shiny and free of nicks. Repeat on the other end of the blade.
Remove the blade from the vise and balance it in the middle. Check to see that it does not tip toward either direction. If it does, you will need to file the side that tips down a little more until it is balanced.
Place the blade back on the lawn mower and tighten the bolt into place.