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How Often Should you Sharpen your Lawn Mower Blades

lawn-mower-blade-sharpeningTo maintain a healthy, green lawn all summer, it’s important to check your mower blade every few weeks to make sure it’s sharp and free of damage. This is will help keep your grass healthy by cutting cleanly, making it easier for the plants to recover. In most cases, a lawn mower blade can be sharpened several times before it has to be replaced, and it’s relatively inexpensive to buy a new one.

When to Sharpen or Replace Mower Blades

For a typical homeowner, the mower’s blade will need to be sharpened at the beginning and middle of the mowing season. If you have an exceptionally large yard or you mow over any debris like branches, toys, glass or metal, your blade may need extra sharpening, or you may need to replace it during the season. If you notice your mower blade has become very thin and weak, replace it immediately. Over time, the metal can weaken as it’s eroded by dirt, sand and other debris from your yard. This can cause the blade to break while you’re mowing, possibly injuring people nearby if pieces of metal fly out of the mower.

How to Tell if Your Mower Blades Need Sharpening

After you mow, take a look at your lawn. If you see missed patches or uneven spots, a dull mower blade could be to blame. A sharp lawn mower blade will cut the grass at the same height in one pass. Another sign is if the grass blades are torn at the ends. A sharpened mower blade will cut the grass cleanly, while a dull blade tears it. This can damage your lawn’s health and even cause it to turn from green to brown.

Of course, you should also inspect the mower blade itself. Look for inconsistencies, dents and chips in the cutting edge. Many of these imperfections can be smoothed out with regular sharpening, but if there are larger nicks or it’s bent, the blade will need to be replaced.

How to Sharpen a Lawn Mower Blade

Whether you have a riding or push mower, check your owner’s manual before starting any repairs or maintenance. This is especially important if it’s under warranty, because it may require you to have the work done by a professional.

Before starting any work on your mower, be sure to remove the spark plug. This will prevent it from accidentally starting on its own.

  1. Remove the mower blade.
    If you have a lawn tractor or riding mower, using a mower lift will help you safely access the blade. For a push mower, you can either set it on its side or use a mower jack to get to the blade. Be sure to keep the air filter up so gas and oil doesn’t leak out.

    Before removing the blade take a picture with your phone, or note which direction it’s facing, so you can put it back on the same way. To stop the blade from turning so you can loosen the bolts, clamp it in place or put a piece of scrap wood between the end of the blade and the mower deck. Use a socket wrench or adjustable wrench to remove the bolt in the middle of the mower blade.
  2. Clean underneath the mower deck.
    Use a putty knife to scrape out any accumulated grass, dirt and other yard debris.
  3. Sharpen the mower blade.
    Clamp the blade in place with a c-clamp and block of wood, or in a bench vise. Use a flat medium file to remove nicks in both sides of the edges. You can remove burrs and nicks from the flat side of the cutting edge by very lightly filing it. The flat side of the blade should not have a bevel, so keep the file flat.

    On the beveled side of the cutting edge, use the medium-toothed file in even strokes, following the blade’s original bevel. To keep the blade in balance, make sure each edge gets the same number of strokes.
  4. Check for balance.
    If you remove more metal from one edge than another, the blade will be out of balance, which can cause the mower to vibrate and cut unevenly. To test for balance, place the blade on a blade balancer, screwdriver handle or dowel. If it’s in balance, the blade will lie flat, but if one side is lower, it needs a little more sharpening to remove excess metal.
  5. Replace the mower blade and spark plug.
    Make sure the blade goes back on the same way, and that you secure it tightly so it won’t come off while you’re mowing.

If you’d rather just replace your mower blade, or you’d rather have a professional take care of the sharpening for you, contact Rental Ranch in Wichita at 316-838-4211.