How to Sharpen Lawnmower Blades

Sharp blades keep grass looking its best.

Lawnmower blades get dull. Not only do they cut grass, but the occasional tree limb and rock also finds its way into the path of the blades. The force behind the spinning blades is enough to cause frequent dulling when cutting grass alone. When the blades strike objects like rocks and twigs it causes nicks in the blades, meaning you'll have to sharpen the blades even more often.

Things You'll Need

• Socket set
• Bench vise
• Mill bastard file

Instructions

1. Tilt the mower to one side so that the bottom of the mower, and the blade, is exposed.

2. Grip the blade with one hand and use a socket to remove the bolt holding the blade in place.

3. Remove the blade from the shaft and replace the mower on all four wheels.

4. Fasten the blade in a vise on a work bench with one of the cutting edges facing up. Alternately you can place the blade on a step or bench with one of the cutting edges overhanging the edge of the bench or step.

5. Take a mill bastard file and begin sharpening the blade. Start with the tip of the file on the edge of the cutting surface closest to the middle of the blade. Push the file forward and along the cutting edge at the same time. Repeat the process as needed to sharpen the blade. Do not pull the file back along the blade. Only file in one direction.

6. Test for sharpness using a sheet of paper. When the blade can cut cleanly through a sheet of paper it is sufficiently sharp for cutting grass.

7. Flip the blade end for end and sharpen the other cutting edge in the same manner. Take an equal number of file strokes on each cutting surface to avoid unbalancing the blade.

8. Tilt the lawnmower on its side again and place the blade back on the shaft.

9. Fasten the blade by reinserting the retaining bolt and tighten it with a socket. Place the mower back in an upright position.

Tips & Warnings

• Make sure to turn off the mower before attempting to remove and sharpen the blade.

• Mill bastard files are available at most home improvement centers and automotive stores.

References

• "Complete Guide to Sharpening"; Leonard Lee; 1995