How to Clean and Sharpen a Mower Blade

Mower blades are the workhorses of your lawn, yet they are almost universally ignored until the grass starts looking ragged and shredded. A dull blade doesn't just make your yard look uneven; it tears the grass instead of cutting it, leaving the blades susceptible to disease and browning at the tips. Maintaining a sharp edge ensures a clean cut that helps your lawn grow thicker and healthier. Getting this done is a matter of discipline rather than specialized skill. You are essentially transforming a piece of neglected metal back into a precise cutting instrument. When done well, you will notice an immediate difference in the sound of the mower and the uniformity of your lawn. Expect a bit of sweat and some grime, but the result is a lawn that looks professionally manicured for the fraction of the cost of a replacement blade.

  1. Kill the Ignition First. Pull the spark plug wire from the spark plug to ensure the engine cannot accidentally start during the process. Tip the mower on its side with the air filter facing up to prevent oil from flooding the carburetor.
  2. Wedge and Unbolt. Use a block of wood to wedge the blade against the mower deck so it cannot rotate. Use a socket wrench to loosen the center mounting bolt, turning counter-clockwise to remove it.
  3. Expose the Edge. Scrape away all dried grass, mud, and caked-on buildup using a stiff wire brush or a putty knife. Use a damp cloth to wipe it clean so you can clearly see the metal edge and any deep nicks.
  4. Restore the Blade. Secure the blade in a bench vise. Using a flat mill file, stroke the cutting edge at the same angle as the existing bevel, usually about 30 to 45 degrees, applying pressure only on the forward stroke.
  5. Level the Blade. Hang the blade on a nail or use a dedicated blade balancer tool by inserting it into the center mounting hole. If one side drops, file a bit more metal off the heavy side until the blade sits perfectly level.
  6. Bolt Back In Place. Place the blade back onto the spindle, ensuring it is seated correctly and facing the right direction. Tighten the mounting bolt securely with your socket wrench.