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A Guide To Sharpening Lawn Mower Blades

Aug. 11 2020 Lifestyle By FMI Equipment

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Lawn mowers need sharp blades to effectively cut grass. Over time, blades get worn down with use and eventually become dull. They need to be sharpened, but there is a right way and a wrong way to do it. We've created the following beginner's guide to the process below. If you have any questions or want to explore lawn mowers for sale, visit FMI Equipment. We are a lawn mower dealership based in Spokane Valley, Washington, and we also serve those in Coeur d'Alene, Idaho.

1. Remove The Lawn Mower's Blade - Safely

The process begins with taking the blade off. But be careful! Even a dull blade can still cause a painful cut if mishandled.

It's also imperative to double (and even triple) check that the lawn mower engine is off. A wise extra safety step is to also remove the spark plug. The engine can't start without a spark plug, so removing it helps prevent the machine from getting accidentally turned on.

When you are ready to remove the blade, make a mark at the bottom using paint or tape. That way, you'll be able to distinguish the sides when you put the blade back.

Next, place the lawn mower on its side. Make sure the carburetor is facing up. Place a 2x4 between the lawn mower's deck skirt and the blade, which helps the blade resist against the board when you remove the bolt. Use a breaker bar or a long handle wrench to loosen the bolt, then remove the blade.

2. Carefully Examine The Lawn Mower's Blade

Next, determine whether the blade needs to be sharpened or replaced. Do a comparison with a replacement blade, which makes it judge the current blade. Plus, the replacement blade will then be ready to go should you need it.

During the inspection, focus on a few key aspects:

  • check that the cutting edge is straight
  • check that the trailing edge is thick
  • check that the cutting edge is free of dents and isn't badly chipped

If the blade falls short in any of these areas, it's due for replacement.

3. Carefully Sharpen The Lawn Mower's Blade

Use a file that is ten inches long (or more). Start each stroke at the top part of the cutting edge. Push downwards with firm and smooth strokes. It usually takes about twenty to thirty strokes to restore the blade to its former sharpness.

During this process, be careful not to do too much sharpening. Over-sharpening can hurt the blade's balance and render it worthless. Keep a replacement blade on hand to use as comparison.

4. Carefully Balance The Lawn Mower's Blade

If the blade isn't balanced, it can vibrate and cause strain on its shaft. Always balance the blade before returning the lawn mower to storage.

The steps to this process are easier. Place a nail in a board. Using the blade's bolt hole, set the blade on the nail. See if the blade tilts to one side. If it does, give that side a quick file down. Make sure to only file a small amount at a time. Then double check your work and see whether the blade needs any more filing. After the blade is balanced, the lawn mower is ready for use again.

We hope you found this guide helpful! For more maintenance advice or to shop lawn mowers for sale, head over to FMI Equipment. We are happy to assist with whatever you need, from answering questions to giving advice. We are a lawn mower dealership located in Spokane Valley, Washington. We also proudly serve those in Spokane, Washington, and Coeur d'Alene, Idaho.