How to Sharpen Lawnmower Blades 

Have you ever gone to cut your lawn and found it more difficult than usual? The mower that used to glide effortlessly across the grass now feeling sluggish and struggling to mow? 

If so, we’re here to give you a hand. In this blog post we’ll explore lawnmower blade sharpening in full, from diagnosing the problem to getting the job done - everything you need to get your mow-jo back.  

Here’s what we’ll cover: 

• How to know if your lawnmower’s blades need sharpening 

• What you need to sharpen lawnmower blades 

• How to sharpen lawnmower blades 

• How often you should sharpen your lawnmower’s blades 

How to Know If Your Lawnmower’s Blades Need Sharpening 

First up, diagnosing the problem. Here are six telltale signs that your lawnmower blade might not be at its best: 

Uneven Cut 

If you find your lawn looking ragged and uneven after cutting, this is a surefire sign that your blade might be blunt. A sharp lawnmower blade should deliver a clean, crisp cut every time.  

You’ll learn to recognise what a good cut looks like. If things look a little different after your latest mow, take a look at your blades to see what’s going on (make sure the lawnmower isn’t connected to the power source). 

Torn Tips 

A dull mower blade will tear grass rather than cut it, and torn grass looks noticeably frayed compared to cut. The ends may also turn brown, a sign that the mower is tearing rather than cutting. 

Increased Effort 

Mowing the lawn isn’t the easiest job, but if you’re finding yourself working even harder than previously, fear not: it’s more likely a dull mower blade that’s responsible rather than your fitness levels! 

As with spotting an uneven cut, you’ll get a feel for how tiring the mowing process should be. If you’re more tired than usual after the latest cut, take a look at the blades. 

Takes Longer 

Similar to the above, if it’s taking you longer to mow as well as being harder work, this could be a sign that your mower is cutting less efficiently than usual. And less efficient cutting, of course, is likely to be because of a dull blade. 

Vibration 

A dull blade can cause the mower to vibrate: if you’re finding the mowing experience to be bumpier and less comfortable than usual, this is another sign that the blade might need sharpening. 

Benefits of Sharpened Lawnmower Blades 

Sometimes you need a nudge to actually do a job that needs doing. If you’ve discovered your lawnmower blades aren’t sharp enough and need some motivation to fix the problem, here are four benefits to sharpened blades: 

1. You’ll have a healthier lawn. This is because sharp blades actually cut the grass, rather than tearing it. The resulting clean cut reduces the risk of pest infestation and improves lawn health. 

1. You’ll mow more efficiently. Sharp blades cut more easily, meaning lower petrol or electricity consumption and, more importantly, less hard work for you! 

1. Your mower will perform better. Sharp blades will also help the mower to function at its best, improving its lifespan and reducing wear and tear. 

 

Feeling ready to get to work? Next, we’ll look at what you need to sharpen mower blades and how to do it. 

What Do I Need to Sharpen Lawnmower Blades? 

There are a few ways to sharpen lawnmower blades, with each technique requiring a different tool. 

Bench Grinder 

This method is fast and efficient, but you need a certain amount of experience to use the tool safely and achieve a well sharpened edge. 

How to do it: hold the lawnmower blade against the rotating wheel of the bench grinder. Apply consistent pressure and maintain a steady angle to ensure an even grind. 

Angle Grinder 

This method is also fast and efficient. You’ll need a steady hand and safety gear, including gloves and eye protection. 

How to do it: secure your lawnmower blade in a vise. Run the angle grinder along the edge of the blade to sharpen it, maintaining a consistent angle and pressure. 

Sharpening File 

This method doesn’t require a power tool: it’s lower cost but more labour intensive.  

How to do it: secure the blade in a vice and manually sharpen the edge. 

Sharpening Kit 

It’s possible to buy purpose-built blade sharpening attachments that you can mount onto drills. These are often easy to use as they include guides to show you the optimal angle for sharpening. 

How to do it: follow the instructions provided with the kit to achieve best results. 

Other Things You’ll Need 

• Bench vice to hold the blades in place 

• Safety gloves 

• Safety goggles 

• Chalk 

• Wrench 

• Blade balancer 

• Stable surface 

How to Sharpen Lawnmower Blades 

Below we provide a step-by-step guide on how to sharpen lawnmower blades with an angle grinder. 

Step 1: Take Safety Precautions 

Lawnmowers can be dangerous. To ensure the lawnmower stays off during the job, remove the spark plug or disconnect it from the power source. 

Put on safety gloves and goggles to protect yourself. 

Check the blade for damage: if there are nicks or heavy damage it may be better to replace the blade than sharpen it. 

Step 2: Get the Mower Ready 

Mark the bottom side of the blade with chalk to ensure you refit it correctly later. 

Use the wrench to remove the nut holding the blade in place. 

Step 3: Clean the Blade 

Clear any dust, dirt or other debris from the blade, to give you a clean surface to work with. 

Step 4: Secure the Blade 

Put the blade in the vice with the cutting edge facing upward. Tighten the vice to prevent the blade from moving. 

Step 5: Sharpen the Blade 

Run the angle grinder’s wheel along the cutting edge of the lawnmower blade, at the original cutting angle. Move from the centre outwards for best results and dip the blade in cool water if it begins to overheat. 

Step 6: Balance the Blade 

Remove the blade from the vice and put it on a blade balancer. If the blade does not remain level, use the angle grinder to remove more metal from the side that drops. This will ensure a balanced blade that functions at its best. 

Step 7: Reinstall the Blade 

Reattach the blade to the mower and tighten the nut. Don’t forget to reinstall the spark plug if you removed it. 

How Often Should You Sharpen Lawnmower Blades? 

To keep your lawnmower and its blades in tip top condition we recommend sharpening your blades once per season, at least. If you mow frequently you might need to do it more often. 

Remember to keep an eye out for the telltale signs we covered earlier in the piece. If you spot a few of these, it’s time to sharpen the blade. 

• Uneven cut: your lawn looks ragged after cutting 

• Torn tips: torn grass looks frayed, and the ends may turn brown, a sign that the mower is tearing rather than cutting 

• Increased effort: you’re having to work harder than previously to mow 

• Takes longer: it’s taking you longer to mow 

• Vibration: A dull blade can cause the mower to vibrate 

Make Sure Your Mower is the Sharpest Tool in the Shed 

A dull lawnmower blade isn’t the end of the world, but it will make it harder to mow your lawn. Thankfully diagnosing the issue and repairing the blade isn’t difficult! We hope this guide has been useful in giving you the info you need to get your lawnmower back to its best condition. 

If you sharpen your mower’s blades and it’s still not cutting your grass how you’d like, it might be time to look at investing in a new lawnmower. 

Still got questions about lawnmowers, blades or anything else tool related? Feel free to get in touch with our team of experts. We’re always happy to answer your questions and connect you with the product or solution you need.