Sharpen Lawn Mower Blades With Grinder

How To Sharpen Lawn Mower Blades With A Grinder

It’s super important to keep your lawn mower blades sharp. Not doing so will affect their performance which could impact the health of your grass. But nobody wants to have to face lengthy maintenance so finding a quick and easy way to get the job done is crucial.

Sharpening mower blades with an angle grinder is definitely one of the fastest and simplest methods. In fact, once you’ve got everything you need, it’ll only take around 15 minutes so you can be back in the garden, relaxing with a cold beer in no time at all!

If you aren’t sure how to sharpen lawn mower blades with a grinder or have never done it before then you’re in the right place. This guide tells you everything you need to know and will have you confidently getting the job done in no time.

Using an angle grinder to sharpen your lawn mower blades is certainly one of the easiest ways to do this job. But before you get started, it’s essential that you prepare and gather everything you need. Once you get started, the last thing you want is to have to down tools to go and look for something you forgot. This is what you’ll need:

  • Angle grinder
  • Wrench set
  • Piece of wood
  • Clamps
  • Bench vice
  • Wire brush
  • Safety goggles
  • Work gloves
  • Rag
  • Lubricant
essentials in sharpening lawn mower blades with grinder

Safety is of the utmost importance when sharpening your lawn mower blades with an angle grinder. Not only is there potential to be cut by the blade but your angle grinder can also be dangerous if it is misused. This is why correct safety gear such as gloves and goggles are essential.

Step 1: Inspect Mower Blades

Before you do anything else, you will need to disconnect your mower from power. If you’re using an electric mower, this simply means unplugging it whereas with a gas powered model, you’ll need to disconnect the spark plug cables. This will avoid any accidental start ups when working on the machine.

Generally speaking, you will need to sharpen your lawn mower blades for every thirty to forty hours of use. Of course, this can vary depending on the quality of the blade and the mowing conditions. But before you start sharpening, it’s really important to take a good look over the blades to assess their condition. This will allow you to see whether they do indeed need sharpening or whether they might have to be replaced.

Access the blades by getting to the underside of the lawn mower. Make sure that you close the fuel valve and always tilt the mower so that the carburetor is facing up, this will stop fuel from leaking into places it shouldn’t go. Of course, you could also completely drain the gas tank but this will take longer.

Now look along the edges of the blades and notice whether there are any rough spots. You should also check whether there are any nicks or cracks and if any rust has developed on the blades. When you’re done inspecting the blade, make a mark on one side as this will make it easier when it comes to reinstalling it.

Step 2: Remove Blades And Clamp Down

You will need to remove the blades before you can work on them and this involves loosening the nut which you’ll find in the middle of the blade. You’ll need to use a socket wrench for this but if you find it a little difficult to turn then it could be that you need to use a lubricant like WD 40 and try again in a few minutes.

You may also notice that the blade rotates as you turn the nut. In order to prevent this, you can use a piece of wood clamped to the underside of the lawn mower to prevent it from spinning.

Once you have successfully removed the blade, pop it into your bench vice and secure it tightly. This will keep it still while you work on it. Partway through the sharpening process, you will need to flip the blade so you can access the other side.

Step 3: Clean The Blade

When it comes to sharpening your lawn mower blades, it’s also a brilliant opportunity to clean them. Use a wire brush to get rid of any dried on grass clippings, dirt and other debris.

Step 4: Run The Angle Grinder Along The Edge Of The Blade

It’s now time to start sharpening your blade and for this, you’ll need your angle grinder. Take the grinder and hold it over the mower blade so it aligns with the cutting angle. Switch on the tool and start running it along the edge of the blade, making thrusting movements towards the inside.

Begin at the tip and slowly make your way down to the part that isn’t sharp and keep repeating this along the entire length of the blade. When you do this, be sure to adjust the angle grinder to match the cutting edge for consistency. Also be sure to only remove a small amount of material; just enough to even out any chips. If you go too over the top, this can cause the blade to crack.

Step 5: Sharpen Other Side Of The Blade

Once you have finished on the first side of the blade, you will need to start working on the second side. This is where you’ll need to take the blade out of the vice, turn it over, and reclamp it. Again, you’ll want to remove any nicks or chips in the cutting edge and file everything down until it’s nice and sharp.

Step 6: Balance The Blade And Sharpen If Necessary

Take the blade out of the vice and find a nail in the wall. Place the central nut hole onto the nail and see how well it balances. You want it to be well balanced and not have one end staying lower than the other. If this happens, it tells you that one end is heavier so the blade has not been evenly sharpened.

If this is the case, don’t worry, you can simply file down the heavier end a little more to bring down the weight before balancing it again. Keep going until the blade remains level. It’s important to be patient here as rushing and reinstalling an unbalanced blade means you will end up with an uneven cut.

Step 7: Apply Grease

Before you reinstall your lawn mower blade, you’ll need to take some oil or lubricant and apply this to the newly cut edges as this will help to stop rust in its tracks. The best way to apply this is to put the oil onto a rag and rub it directly onto the blade, being careful not to cut your hands.

Step 8: Reinstall Blade

Finally, it’s time to put your lawn mower blade back into position. Do this by replacing the nut you removed earlier on. Make sure that you tighten it well with your socket wrench so that the blade is secure. But avoid over tightening as this can prevent the blade from moving properly.

You can now take out that piece of wood you clamped into the deck earlier and give the blade a spin to make sure it’s installed correctly.

Can You Sharpen Mower Blades With A Hand Grinder?

There are plenty of effective ways to sharpen a lawn mower blade and that includes with a hand grinder. Grinders are seen as heavy duty tools whereas a lot of people think that precision is needed to sharpen a lawn mower blade.

But the truth is that we aren’t sharpening a pristine Japanese kitchen knife. In fact, lawn mower blades only need to be sharpened enough so that they have a decisive edge; there’s no need for them to be razor sharp. A hand grinder is a great way to achieve this.

What Is The Best Angle To Sharpen A Lawn Mower Blade?

Lawn mower blades typically need to be sharpened somewhere between 45 and 60 degrees. But this can vary between models so it’s really important to check in your owner’s manual as this will provide you with specific information relating to your model. If you no longer have your owners manual or cannot access it online, just try to keep to the existing angle as closely as possible.

How Many Times Can You Sharpen A Lawn Mower Blade?

You will need to sharpen your lawn mower blades for every 30 to 40 hours of mowing. This will vary depending on several factors such as the conditions, the type of grass and the quality of the blade. Generally speaking, you should be able to sharpen your lawn mower blades two or three times before you need to buy new ones.

Final Thoughts

If you want your lawn mower to keep performing at its best then it’s vital to perform regular maintenance. One form of maintenance is to sharpen the blades and this will normally need to be done between every thirty and forty hours of mowing.

There are lots of methods you might use but an angle grinder is a fast and efficient way to get those blades sharp. It’s easy to do and doesn’t typically take longer than 15 minutes.

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Andrew Fisher

Andrew Fisher

Andrew is a dedicated father of three who really takes pride in his lawn and garden. You'll find Andrew behind the scenes of almost everything Edge Your Lawn produces. When he's not helping readers find all the information they need, he's in his backyard working on his lawn and garden landscaping. This year he hopes to build an outdoor deck and sort out his veg patches.

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