How to Sharpen Lawn Mower Blades?

A sharp blade is very important for lawns. Below are step-by-step instructions.

When to Sharpen a Lawn Mower Blade

Sharpen lawn mower blades to keep your lawn looking nice. This prevents grass from being cut unevenly.

Regularly check the blade. Do not wait until cutting results get worse. Check whether it needs sharpening or replacement.

Replace a Damaged Blade

If you find a crack in the lawn mower blade, do not try to sharpen it. Simply replace the blade.

How Often Should the Blade Be Sharpened?

Even if there are no problems during regular checks, you should still sharpen the lawn mower blade.

Should I Sharpen the Blade Myself or Take It to a Professional?

Your local STIHL DEALER has the tools and experience needed to properly sharpen your lawn mower blade. If you have the right tools, you can also sharpen it yourself. Just follow the instructions.

How to Sharpen a Lawn Mower Blade: Step-by-Step Guide

You will need:

Strong vise

Work gloves

Wrench

Pipe wrench (monkey wrench)

Device

Small stone

Balancing device

Step 1: Turn Off the Mower

Before you start sharpening, make sure the mower is switched off and cannot start accidentally. If it is electric, unplug the cord. Do not wrap the cord around the tool. If it is cordless, remove the battery. If it is gasoline-powered, disconnect the spark plug.

Step 2: Position the Mower

To sharpen, you need access to the blade from underneath. Be careful. Electric mowers can be turned over, but gasoline mowers should not. In gasoline mowers, the air filter must always be facing upward. To access the blade, you can tilt it 45 degrees.

Step 3: Remove the Blade

Bolts are always right-threaded. They must be turned counterclockwise. Wear gloves while loosening and removing the bolts. Hold the blade with one hand and remove the bolt with the other.

Step 4: Clean the Blade

Remove grass residue from the blade. Check for cracks or dents. If there are any, replace the blade.

Step 5: Secure the Blade

To sharpen the cutting edges, secure the blade with a vise. Place a protective pad between the vise jaws and the blade.

Step 6: Sharpen the Blade

Work along the curved edge in one direction. Continue until the edge is smooth. Maintain a 30° sharpening angle.

STIHL professional tip: For a smoother result, apply a little chalk to the file.

Step 7: Balance the Blade

Remove the blade and place it on a balancing device. If it stays level, it is balanced. If it tilts, remove excess weight and repeat steps 6 and 7.

Summary: How to Sharpen Lawn Blades

Disconnect power to prevent accidental starting.

Inspect the blade; replace it if there are cracks or holes.

Sharpen every 20–25 operating hours or when worn.

Secure the blade with a wrench and sharpen at a 30° angle.

Balance the blade; remove excess material until it stays level.