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Learn how to sharpen lawn mower blades using an angle grinder with our step-by-step guide. Keep your lawn mower in top condition and achieve a cleaner, more efficient cut with these easy-to-follow instructions.
Also read our more comprehensive guide on sharpening lawn mower blades, including different ways to do it.
Image credit: warren_price/Adobe Stock
Tools Needed
- Angle grinder
- Wrench or socket set
- Blade balancer (optional)
Materials Needed
- Block of wood
- Marker or paint
- Lubricant
- Clamps
- Wire Brush
- Safety goggles
- Ear protection
- Work gloves
Step-by-step Guide (5)
1. Remove the Lawn Mower Blade and Prepare it
Your primary concern should be safety, so disconnect the spark plug to prevent any accidental starts.
Next, tilt the lawn mower on its side with the carburetor and air filter facing up. This position will keep oil from spilling into other parts of the mower.
Once you’ve got your lawn mower in a comfortable position, find a block of wood to wedge between blade and mowing deck. This will prevent the blade from spinning while you loosen it up.
Pro tip: You can mark the side of the blade that is facing out by using a marker or spray some paint, so that you then can reinstall the blade in the correct way after you have sharpened it.
Hone in on the bolt at center – it’s usually one single bolt holding down our proverbial Excalibur and turn it counterclockwise with your wrench or socket set until it comes free. Use lubricate to make the bolt come off easier.
You might also want to give your blade a good cleaning before proceeding further. Scrape of dirt and bigger things with a wire brush, and then use some soap to get a super clean blade.
2. Sharpening the Blade With the Angle Grinder
You came here to learn how to sharpen lawn mower blades with an angle grinder, right? Well here it is:
Start by holding the blade firmly against a stable surface using clamps, if possible. We want to keep that sucker steady while we work our magic.
Now, position your angle grinder at a 45-degree angle towards the cutting edge of the blade. You’ll want to make smooth passes along it, allowing the grinder wheel to do its job without forcing it too much into the metal.
Pro tip: When using an angle grinder for sharpening, slow and steady always wins the race. Take your time and make light passes over the blade using the tool.
3. Balance the blade
To balance the blade, place it on a balancing tool which is specifically designed for this purpose. If one end of the blade tilts downward, it means that end is heavier than the other. Take up your angle grinder once again and gently grind away some more metal from the heavier side.
Keep repeating these steps until both sides weigh equally.
Pro tip: If you don’t have access to a balancing tool you can use a nail lodged in a wall. Place the center hole of the blade onto the nail and see which way it tilts.
4. Reinstall the Blade
Just remember how you took out the blade in the first place. Position the blade onto its spindle, making sure that the marked side of the blade is pointing outwards.
If there were multiple bolts or nuts involved in holding your blade, try attaching them loosely at first before tightening each one subsequently. This way, you can ensure that all parts fit together as they should without forcing anything into place.
5. Test the Mower
Observe how smoothly your lawn mower runs now after the sharpening. Are there any unusual vibrations or noises?
Everything should run as smooth as silk if you balanced the blade properly. Also, inspect the grass once you’ve made a few passes with your freshly sharpened blade.
You should be able to see clean cuts; jagged grass tips are indicative that something went awry during sharpening or reinstallation. At any rate, don’t despair if things didn’t go as planned in this first trial – remember that practice makes perfect.
And that’s how to sharpen lawn mower blades with an angle grinder!
