Sharpen Mower Blades – Turfgrass Science at Purdue University

Sharpen Mower Blades

Due to the warm, wet weather we have been experiencing lately, homeowners are having to mow their lawns very frequently. Something to keep in mind throughout the summer is that the more often you mow your lawn, the more dull the mower blades become. Mower blades should be examined a few times throughout the growing season and may need sharpening as much as four to six times a year. Dull mower blades rip the grass blades rather than cutting them cleanly. This leaves ragged leaf tips that give the turf a whitish cast when viewed across a distance. Ripping the grass leaves the turf damaged and very susceptible disease pathogens to penetrate and infect the plant.

In order to sharpen your mower blades at home, you must first remove the spark plug wire to ensure the mower does not start up while you are filing. This could cause serious injury! For a quick sharpen, the blade can be clamped in a vise and filed along the cutting edge. To sharpen a more dull blade, remove the nut that connects the blade to the deck with a wrench and remove the blade. File along the cutting edge (about a 45 degree angle). Make sure to pass the file the same number of times on each side and try to apply equal amounts of pressure to keep the blade in balance. If you think the blade is unbalanced, place the blade on a plastic balancer and make sure that the blade is level. If one side dips down, file the heavier side to lighten it. Repeat this process as often as is necessary.


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