A lawn mower blade is hard steel – a diamond file makes sharpening quick and easy
If your lawn mower is tearing the grass instead of cutting it cleanly, it's probably time to sharpen the blade. In the video below, I show how I do it. There are many ways to sharpen a lawn mower blade, but this is my annual maintenance routine. Since I do it regularly, it usually only takes a few minutes.
- Cleaner cuts
- Less strain on the engine
- Better grass collection
- Takes only a few minutes
Tip: Avoid laying the mower on its side. Oil can enter the cylinder and cause starting problems or even lock the engine. It's easy to fix, but unnecessary.
Important: Disconnect the spark plug before turning the blade by hand.
In this video I'm using a Dianova Diamond File. The file side works well for lawn mower blades and other heavy-duty tools, while the diamond sharpening side is ideal for garden tools that require a sharper edge.
It's also the same file I use to sharpen the carbide tips on my roller ski poles.
The Process
1. Hold down the safety brake and tilt the mower
Keeping the blade free to rotate makes the job much easier.
2. Disconnect the spark plug
Especially if the engine is still warm, it may start surprisingly easily. Better safe than sorry.
3. File the bevel at the original angle
The outer section of the blade does the actual cutting. On my mower, I only sharpen the outer 8 cm (about 3 inches).
4. Remove the burr
Place the diamond file flat against the underside of the blade and lightly remove the burr created in the previous step. Do not remove much material from this side. Most of the sharpening should be done from the bevel side.
5. Rotate the blade
Repeat the process on the other side until both cutting edges feel even and sharp.
They don't need to be razor sharp, but a clean edge is always beneficial.
6. Finish with light strokes
Use a few light alternating strokes to reduce the burr and refine the edge.
7. Reconnect the spark plug
Easy to forget. Ask me how I know.
The Result
Five minutes later, the mower was cutting cleanly again.
