How To Sharpen A Lawn Mower Blade

lawn mower blade splash

Sharpening a lawn mower blade is important to keep your lawn healthy and green. A sharp blade will cut the grass blades instead of tearing the grass blades. A dull blade will tear the grass blades which results in silver or brown grass blades, this makes your lawn look brown or silver. Torn grass ends also make the lawn more susceptible to disease. This article teaches you how to sharpen and balance your lawn mower blade.

When the blade is sharp it cuts the grass more times before it gets thrown from the mower. This helps with mulching.

Mower Blades should be sharpened once a year if you mow once a week during a normal three season schedule. With more use you may want to sharpen it more often.

brief how to

In this article, you will find information about:

  1. Disconnect The Spark Plug
  2. Block The Blade From Moving
  3. Use Wrench To Remove The Blade Bolts
  4. Sharpen The Blade Or Purchase A New Blade
  5. Balance The Blade
  6. Attach The Blade
  7. Connect The Spark Plug

tools and materials

    • lawn mower
    • Socket wrench for blade bolts
    • Grinder wheel or file
    • Nail to balance the blade on

step 1 Disconnect The Spark Plug

Remove the spark plug by disconnecting the spark plug wire from the top of the spark plug.


step 2 Block The Blade From Moving

Use a piece of wood to prevent the blade from moving when it is turned. It works well to put the wood thru the discharge chute as shown in the image.


step 3 Use Wrench To Remove The Blade Bolts

Use a wrench to remove the bolts holding the blade on. Bolts are typically attached with two bolts.


step 4 Sharpen The Blade Or Purchase A New Blade

There are two options to get a sharp blade, replace the blade or sharpen the blade. If the blade is badly damaged, dented or bent beyond repair, then you will need to replace it with a new one.

sharpening: If you are able to sharpen it you can either take it to a blade sharpening service or sharpen it yourself using a grinder or file. If the blade has a lot of large dings then you should use a grinder to grind them out. If the blade only needs minor fine tuning then you may be able to use a flat file. Try to grind/file the blade to the same angle as installed when it was made.

blade heat: If using a grinder make sure to not allow the blade to heat up by moving the grinding wheel across the blade and not holding in a single spot long enough to let the blade heat up. Excessive blade heat will cause the blade to lose its temper and therefore not be as strong.


step 5 Balance The Blade

Balancing the blade is critical to keeping your mower running smoothly and to keep it from damaging the mower. A blade out of balance will vibrate and cause pre-mature failure of the bearings that the blade spins on. After the blade is sharpened it may be out of balance because steel has been removed from it.

Use either a blade balancing kit purchased from a store that sells lawn mowers or a nail nailed to a wall. This article shows how to balance a lawn mower blade using a nail.

These are the steps to balance the lawn mower blade:

  1. Put a nail into a wall and hang the blade on it thru its center hole..
  2. Make sure that the blade is centered.
  3. Let go of the blade and see if either side drops.
  4. If one side drops remove steel from the end, not the cutting edge, of the blade that is heavier.
  5. Put the blade back on the nail and check to see if it is balanced.
  6. Repeat this process until the lawn mower blade is balanced.


step 6 Attach The Blade

Make sure there is no grass or other debris to keep the blade from sitting tight against its mount. Attach the blade to the lawn mower. You will need to re-position the wood block so the blade will bind against it when it is rotated in the opposite direction while turning the bolts clockwise.

step 7 Connect The Spark Plug

Connect the spark plug wire to the spark plug. Be careful to make sure the metal tabs that clamp the top of the spark plug are not bent and that they will fit snugly on the top of the spark plug. When you push it onto the top of the spark plug make sure it snaps onto the end of the spark plug.

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