Things To Keep In Mind While Sharpening Mower Blades

Last Updated on July 15, 2023 by Kimberly Crawford

Maintaining a well-groomed lawn needs more than just regular mowing. Neglecting the sharpness of your land mower’s blades can result in lackluster results. Over time, the continuous spinning of the blades makes them lose their keen edge.

When this happens, instead of smoothly slicing through the grass, the blades start tearing it, leaving the lawn with a ragged, unsightly appearance. It compromises the lawn’s aesthetic appeal and makes it susceptible to diseases.

Fortunately, you can bring back your lawn’s health and vibrancy with effort and basic tools. This guide will give you a step-by-step guide on sharpening mower blades.

Sharpening Lawn Mower Blades

Step 1 – Prep to sharpen the blades

  1. Gather the necessary equipment and tools – Here are some things you will need for this process:
  • Gloves
  • Safety glasses or goggles
  • Various boards of different lengths (12″ to 18″)
  • A 16″-20″ long 2×4 wood block
  • A paint stick
  • A 4×4 wood
  • Penetrating oil (optional),
  • Spray paint or Permanent marker
  • Steel wool and/or wire brush
  • Grinder or file
  • A breaking bar with a socket
  1. Prioritize safety – Wear safety gloves and goggles throughout the process.
  1. Disconnect all power sources – Unplug the mower if it is electric or disconnect the spark plug cable if you have a gasoline-powered mower.
  1. Turn the mower on its side – Place the mower on either side for the electric mowers, or position the carburetor facing upwards for gas mowers. Use multiple boards or a block for stability.

Step 2 – Removing the blade

  1. Mark the blade’s bottom side – With a permanent marker, spray paint, or a paint stick, mark the blade’s bottom side for proper reinstallation.
  1. Secure the blade for removal – Wedge a 2X4 under the blade and over the cutter deck to ensure it does not turn counterclockwise.
  1. Loosen and remove the blade – Use a breaking bar and apt socket to apply torque and loosen the nut. Use a penetrating oil if required. Unscrew the nut, remove the sleeves, washers, and blade, and take note of their order.

Step 3 – Sharpening the blade

sharpen lawn mower blade

Source: Home Depot

  1. Secure the blade for sharpening – Use a vice to hold the blade with one cutting edge facing upward and tighten the vice.
  1. Clean off debris – Clear rust and grass build-up near the cutting edge with a wire brush, steel wool, or a cold chisel.
  1. Sharpen the blade – Use a hand grinder or a flat file to sharpen the blade. Maintain a 45-degree angle, make even strokes from the inside to the outside of the cutting edge, and avoid drawing backward. Flip the blade and sharpen the other edge with similar strokes for uniformity.

Step 4: Reinstalling the Blade

  1. Properly position the blade – Align the blade as per the marking if marked, and place the sleeves and washers in the correct order. Thread the nut via the blade hole into the drive shaft and finger-tighten it.
  1. Tighten the nut – Use a 2X4 wedge to resist clockwise turning, position the breaking bar over the three o’clock position, and apply downward pressure to tighten the nut securely.
  1. Prepare to mow – Remove the wedge, place the mower back on the wheels, and reconnect the spark plug cable for gas mowers. For electric mowers, plug it in, turn it on, and begin mowing.

By employing the above-stated step-by-step instruction, you can sharpen your lawn mower blades effectively, resulting in improved mower performance and a more vibrant and healthier lawn.

Sharpening Lawn Mower Blades Without Removing Them

Step 1 – Prepare to Sharpen the Blade

  1. Gather the necessary equipment and tools – Here are some things you will need for this process:
  • A 16″-20″ long 2×4 wood block
  • Safety glasses or goggles
  • Gloves
  • An additional 4×4 wood block (12″-18″)
  • Grinder or file
  • Steel wool or/and wire brush
  1. Make safety a top priority by wearing protective goggles or glasses and gloves consistently throughout the process.
  1. Safely disconnect all power sources: If your mower is electric, unplug it from the power source. Disconnect the spark plug cable for gas mowers to ensure no accidental starting.
  1. Position the mower on its side: Carefully place the mower on its side, ensuring the carburetor is facing upward for gas mowers. Use one or more blocks to provide stability during the sharpening process.

Step 2 – Sharpening the blade

  1. Secure the blade: Wedge a 2×4 under the blade and over the cutting deck to prevent it from turning.
  1. Clean off debris: Clear any caked grass, rust, or debris from the blade to ensure unobstructed access to the cutting edge.
  1. Sharpen the blade: Using a file or grinder, follow the same sharpening technique as if the blade were removed. Remember the following guidelines:
  • Make even strokes
  • Maintain the proper angle
  • Avoid drawing backward
  • Flip the blade and sharpen the other edge

With this step-by-step instruction above, you can sharpen the lawn mower blades without removing them. It lets you complete the task efficiently. Always prioritize safety and maintain the proper sharpening techniques to ensure optimal mower performance and achieve a healthier, prettier lawn.

Some helpful tips

Below are some vital tips to consider regardless of whether you choose to sharpen the blade on the mower itself or by removing them:

  1. Determine when blades are dull – Examine the grass blades for signs of tearing or splitting at the tips, indicating the need for sharpening.
  1. Sharpen with an empty gas tank – To avoid fuel loss, sharpen the blades when the mower’s gas tank is empty or ensure it is empty before you commence the process.
  1. Ensure proper blade balance – Check for proper balance by listening for any unusual noises from the mower deck. An imbalanced blade may result from a worn-out driveshaft hole or bending.
  1. Address nicked blades – Consider grinding them out with a bench grinder if you spot minor nicks on the blade for optimal results.
  1. Understand when to replace blades – Blades with a severely worn-out driveshaft hole, excessive nicks, significant bending, or imbalance may need replacement with new blades.

By bearing these tips in mind, you can accentuate the effectiveness and efficiency of the lawn mower blade sharpening process.