Same as with dull knives or scissors – they don't cut efficiently and result in the need to duplicate work. On a mower, worn blades have trouble lifting grass while mowing, and they don't cut well, leaving behind an uneven cut and stragglers. If blades are worn too much, it might require mowing the same rows twice.Dull blades may need replacement, which isn't bad since new blades are relatively cheap and easy to replace. However, if enough blade material still exists, the blade can be sharpened.Blades should be discarded if more than a half-inch of the blade material is worn away (by previous sharpening or wear) or if the air lift (the bend in the blade) is eroded.

Sharpening blades is a wasted effort if the blades can no longer lift the grass and cut it evenly, and blades that are bent or broken can be dangerous and cause damage.Handling mower blades can be dangerous and is best left to those with knowledge and experience replacing blades. If you're uncomfortable with this procedure.Read the safety instructions in the operator's manual before starting.Remove the deck as instructed in the operator's manual.Remove the blades according to the directions in the manual.File or grind an equal amount of blade material from each cutting edge of the blade until sharp.

Do not change angle of cutting edge or round the corner of the blade.Insert a screwdriver through the hole in the blade and hold the screwdriver horizontally. Position the blade horizontally and check for blade balance. This is critical. If the blade moves, sharpen the heavy end until the blade remains balanced in a horizontal position on the screwdriver.When the blade is sharpened and balanced adequately, reinstall it and torque it to the specification listed in the operator's manual.Mower decks packed with grass clippings, dirt and debris can damage your mower, affect cut quality and hurt lawns. Grass, dirt and debris holds moisture that corrodes bare metal on the spindles and mower blades, weakening them.

Additionally, grass-packed cutting Lawn mower steering parts decks can harbor fungi and bacteria that can spread around your lawn and damage it.​Grass buildup around the discharge area can prevent clippings from discharging evenly and could lead to clumping. Remove the mower deck as instructed in the operator's manual for your unit and remove the mower blades.​Removed clumped grass from under the mower deck and wash with low-pressure water and a mild soap solution until all dirt, grass and debris is washed away from the deck.