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Why Sharpening Lawn Mower Blades is Important
In addition to damaging your lawn, a dull blade puts extra stress on your lawn mower's engine, leading to decreased fuel efficiency and potential mechanical issues. By regularly sharpening your lawn mower blades, you get a precise cut, while promoting the overall health and appearance of your lawn.
Sharpen the blades of your lawn mower based on how often use your lawn mower. Ideally, you should sharpen the blade after every 20 to 25 hours of runtime. Keep a spare lawn mower blade for when your other blade needs maintenance.
When to Sharpen Your Lawn Mower Blades
- If your lawn mower blade is dented or bent it’s time to sharpen.
- A dull blade can cause the lawn mower engine to seize. If your lawn mower stalls often, try sharpening the blades to solve the problem.
- If your lawn looks patchy and uneven. If you must push the lawn mower harder and you find yourself trimming an area multiple times, try sharpening or replacing the lawn mower blades.
1. How to Remove the Lawn Mower Blade
To sharpen the blade, remove it from the lawn mower. Before you start, don’t forget to put on your safety gloves and safety glasses. Remove the lawn mower battery or disconnect the spark plug wire to prevent accidental starting.
- Position the mower on a flat and stable surface, like a workbench or the floor of a garage.
- Using a socket wrench or adjustable wrench, loosen the bolt or nut that secures the blade to the spindle. Remember to turn it counterclockwise.
- If the blade is difficult to remove, use a blade removal tool or place a block of wood between the blade and the mower deck for leverage.
- Carefully lift the blade off the spindle and set it aside.
2. Inspect and Clean the Blade
Once you’ve removed the blade, inspect it for signs of damage or wear. Look for cracks, nicks or dullness. Replace the lawn mower blade if it’s damaged. If it's dull it just needs sharpening. Before sharpening, clean the blade using a wire brush or rag to remove debris or built-up grass clippings.
3. Choose a Mower Blade Sharpening Method
There are two methods for sharpening lawn mower blades: using a drill attachment grinder or a file. Secure the blade in a vise or clamp, and make sure it’s stable and won’t move while sharpening.
Sharpen a Blade Using a Drill
- Attach the grinder to your drill and tighten.
- Adjust the angle of the grinder to match the existing bevel on the blade. Maintain the original angle for optimal cutting performance.
- Turn on the grinder and slowly move it along the blade. Move the grinder back and forth across the blade for even sharpening.
- Remove the grinder from the blade periodically to cool it and prevent overheating.
- Continue sharpening until you’ve restored a sharp and even edge to the blade.
Sharpen a Blade by Hand
- Using a file, work along the original cutting edge, following the existing bevel. Maintain a consistent angle and apply even pressure while filing.
- Make long, smooth strokes in one direction, lifting the file on the return stroke to avoid dulling the blade further.
- Repeat the filing process until the blade is sharp and the cutting edge is even.
4. Balance and Reinstall the Lawn Mower Blade
After sharpening the lawn mower blade, it's important to check its balance. An unbalanced blade can cause excessive vibration and potentially damage the mower. Follow the steps below to balance and reinstall the blade.
- Place the blade on a blade balancer or balance it on a sturdy nail.
- If one side of the blade dips lower than the other, it indicates an imbalance. To correct the imbalance, remove a small amount of metal from the side that is heavier using a file or grinder.
- Continue removing material until the blade is balanced evenly.
- To reinstall the blade, align the center hole of the blade with the spindle on the mower deck.
- Carefully slide the blade onto the spindle, ensuring it sits flat against the mower deck.
- Tighten the bolt or nut that secures the blade, turning it clockwise with a socket wrench or adjustable wrench. Make sure it's securely fastened.
5. Maintenance Check Before Using Your Mower
Before you start mowing your lawn, perform a quick maintenance check:
- Reconnect the spark plug.
- Inspect the lawn mower for any loose or damaged parts.
- Check the oil level and fill it up if necessary.
- Test the mower by starting it and checking that everything is functioning properly, then start mowing.