How to sharpen and change lawn mower blades

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Keeping your lawn mower blades sharp and in good condition is essential for maintaining a healthy, even lawn. This is especially important in Victoria, where seasonal changes like wet autumns and dry summers can put extra stress on your grass. Dull blades tear the grass rather than cut it cleanly, leading to brown tips, disease, and an uneven appearance. Whether you need to sharpen or replace your mower blades, knowing the proper techniques ensures a smooth and effective mowing experience.

In this guide, we’ll discuss how to sharpen and change lawn mower blades and best practices for keeping them in top condition. Watch our video for a visual guide on how to conduct the process. 

Why sharp lawn mower blades matter

When mowing, keeping your blades sharp is crucial if your goal is to achieve a fresh, vibrant-looking lawn. Dull blades can cause damage to the grass, making it more susceptible to disease and uneven growth. Sharp blades result in a clean cut, reducing stress on your grass and promoting healthier growth. Here’s why keeping your mower blades sharp is important:

• Prevents grass tearing, which can lead to brown, unhealthy patches.
• Reduces fuel consumption and engine strain, improving mower efficiency.
• Ensures a smooth, professional-looking cut every time you mow.
• Essential for overall lawn maintenance, especially with Melbourne’s year-round mowing needs.

How to change lawn mower blades

If your mower blade is damaged, bent, or excessively worn, replacing it is the best option. Here’s how to change blades on a lawn mower safely and effectively.

Tools needed:

Before starting the blade replacement process, ensure you have all the necessary tools on hand. This will make the process smoother and help prevent any unnecessary delays. Before you begin, gather the following tools:

• Socket wrench (to loosen the blade bolt)
• Work gloves (for safety)
• Wood block or clamp (to keep the blade from rotating)
• New mower blade (ensure it matches your mower model)
• Penetrating oil (if the bolt is stuck)

Steps to change lawn mower blades

Following the correct procedure for changing your lawn mower blades will ensure a safe and effective replacement. These steps will help you avoid common mistakes and ensure optimal mower performance.

1. Turn off the mower and disconnect power
   • For petrol mowers: Remove the spark plug.
   • For electric mowers: Disconnect the battery or unplug it.
2. Secure the mower and blade
   • Tip the mower onto its side (fuel tank side up to avoid leaks).
   • Use a wooden block or clamp to prevent the blade from moving.
3. Loosen and remove the blade
   • Use a socket wrench to remove the blade bolt (turn counterclockwise).
   • Apply penetrating oil if the bolt is rusted or difficult to loosen.
4. Install the new blade
   • Position the new blade correctly (match the old blade’s orientation).
   • Tighten the bolt securely but avoid over-tightening.
5. Reconnect power and test
   • Reattach the spark plug or battery and test the mower.
   • Ensure the blade rotates freely before starting.

How to remove lawn mower blades without causing damage

Removing lawn mower blades incorrectly can cause damage to your mower or result in injury. Follow these tips to safely remove the blades without any issues. 

• Apply penetrating oil and let it sit for a few minutes before loosening.
• Use a rubber mallet to gently tap the blade bolt if stuck.
• If the bolt is stripped, use a bolt extractor tool for removal.

How to sharpen lawn mower blades

Sharpening your lawn mower blades extends their lifespan and improves cutting performance. Aim to sharpen your blades every 20-25 hours of mowing or when you notice uneven cutting.

Tools needed for sharpening:

Having the right sharpening tools is essential for achieving a clean, sharp edge on your lawn mower blades. Using improper tools can result in an uneven sharpening job or even damage the blade.

• Metal file (for manual sharpening)
• Bench grinder or angle grinder (for faster sharpening)
• Clamps or vice (to secure the blade)
• Work gloves and safety glasses
• Blade balancer (to ensure even sharpening)

Steps to sharpen a lawn mower blade

Properly sharpening your lawn mower blade will extend its lifespan. Follow these steps to sharpen the blade and ensure it remains effective.

1. Remove the blade (Follow the steps above for safe removal.)
2. Clean the blade
   • Remove dirt, grass clippings, and rust with a wire brush.
3. Secure the blade for sharpening
   • Clamp the blade securely in a vice.
4. Sharpen the cutting edge
   • If using a metal file, sharpen in one direction with consistent strokes.
   • If using a grinder, apply light pressure and follow the blade’s original angle.
5. Check for balance
   • Place the blade on a blade balancer to ensure even sharpening.
   • If one side is heavier, file or grind it down slightly.
6. Reinstall the blade
   • Follow the installation steps mentioned earlier.

Best practices for maintaining sharp lawn mower blades

Routine maintenance of your lawn mower blades will help keep your mower operating at peak efficiency. Following these best practices will help ensure a consistently sharp blade and a well-maintained garden.

• Sharpen regularly – Every 20–25 hours, or more often during Melbourne’s growing season.
• Inspect for damage – Check for bends, cracks, or excessive wear.
• Clean after mowing – Remove stuck grass and dirt to prevent rust.
• Balance the blade – Uneven sharpening can cause mower vibrations.
• Store properly – Keep spare blades in a dry, rust-free area.
• Adjust for the season – Victorian lawns grow faster in warmer months.

Get expert lawn solutions from Lilydale Instant Lawn

Changing and sharpening your lawn mower blades is an essential part of lawn maintenance. With sharp blades, your lawn will look healthier, your mower will run efficiently, and you’ll achieve a professional-quality cut every time.

At Lilydale Instant Lawn, we provide high-quality Kikuyu, Buffalo, and Couch turf to help you achieve the perfect lawn. Need more lawn care tips? Contact our professionals for expert advice on maintaining a lush, green lawn in Melbourne.