How to Sharpen Mower Blades with Angle Grinder

If you’ve ever wondered how to sharpen mower blades with angle grinder, then you’re in the right place! This article shows you how to sharpen your mower blades in a manner that is fast, safe, cheap, and easy!

When I was mowing my lawns on the weekend, I noticed that I was ripping out large chunks of turf as I was going. As the job went on, the battery on my Ryobi 36v mower wasn’t lasting as long either. I quickly realized it was time to sharpen my mower blades!

Sharpening your mower blades with an angle grinder is a simple job, that leaves your mower cutting lawn like a knife through butter.

Tools You Need:

-Blunt lawnmower blade (trust me, yours is blunt)
-Angle grinder
-Flap disc grinder blade
-Clamp or vice
-Safety goggles
-Hearing protection
-Spanner set

How to sharpen mower blades with angle grinder

Step 1: Remove the power source

With a battery mower like mine, simply pull out the battery! For petrol/ gas mowers just pull off the spark plug cap, making sure it doesn’t come into contact with the spark plug.

This is an important step, as it is possible to manually start a mower just by moving the mower blades!

Step 2: Turn the mower on its side

If you have a battery mower, you can just put it on its side straight away without any issues. Battery mowers have no fluids running around, so you won’t damage the engine in any way.

Gas mowers need to be treated a little more carefully. It can be helpful to open the fuel cap, put a plastic bag over the hole, and close the cap over it. Check out this video for a better explanation. Also, you should make sure your mower is turned with the carburetor facing up. At this point, it’s helpful to either do this job outside or put something under the mower to catch any spilled fluids.

How to sharpen mower blades with angle grinder

Step 3: Take a photo!

Anytime I pull things apart, I always take a photo so I can remember where things go. It can be a pain in the butt remembering which way is up on the lawn mower blade, as well as the order that all the nuts, bolts, and washers go in.

Step 4: Remove the blade

Remove the nut holding the blade in place. I sharpen my mower blades twice a year, so the nut was pretty easy. If it is stuck firmly, it’s helpful to place or clamp a block of wood against the blade to stop it from moving.

Please don’t grab the blade with your hands! While your blade needs sharpening, it is by no means dull- especially if you’ve hit some rocks along the way. Nobody wants a trip to the emergency room for a tetanus shot on the weekend!

I used a spanner to remove the nut, you can also use a socket wrench, an impact driver, or even a rattle gun! It all depends on how hard the nut is fastened.

Step 5: Clamp and Sharpen!

Clamp your blade, cutting side up to a solid surface. Don your protective gear and grab your angle grinder with the flap disc. To sharpen the blade, simply make light, slow passes along the length of your blade. Don’t get too fancy here! You’re not trying to create a brand-new edge. Rather, just follow along the existing edge and tidy it up a little. Keep the same angle as best as you can.

Newer mower blades are made of super soft metals, sometimes jokingly called Chinesium. I actually don’t mind these soft blades, as it means you can get a nice fresh edge with a flappy disc on your grinder. For these tasks, a full metal grinding disc is not necessary and is actually a little more difficult to do.

The flap disc should work on older blades, too; you might just need to make a few more passes.

The aim here is not to make the blade razor-sharp! Simply tidying up the edge will do the trick!

Step 6: Clean the deck and reassemble it.

I’m a bit embarrassed with the state of my lawn mower. There’s far too much dry grass and dirt to post pictures on the internet. So, before you reassemble your mower, scrape off all of the old grass and debris. It can also be helpful to give the underside of your mower a nice little wash!

Whip out your phone and look at the picture you took at the start. Reassemble your nuts, washers, and mower blade and tighten them firmly. Remember, you need to do this all over again in 6 months’ time! So don’t go overboard with the tightening.

Step 7: Test drive

The best part of sharpening your mower blades is seeing how much better your mower cuts afterward. So take it out for a test drive, and enjoy that new mower feeling!