How to Sharpen a Rotary Lawn Mower Blade
- 1). Open your lawn mower's protective case and disconnect the spark plug wire. You may want to consult your mower's manual for a parts diagram if you've never attempted this on your mower before. Disconnecting this wire will make it impossible for the mower to accidentally start while you're removing or reinstalling the blade.
- 2). Tip the mower on its side, being careful not to spill any fluids like fuel or oil. Use a hand wrench to remove the bolts holding the blade into place.
- 3). Use vice clamps to clamp the blade onto your work bench or another strong, stable surface.
- 4). Examine the angle of the blade edge and study it closely if you're inexperienced with blade sharpening. It's important to sharpen the blade at the original angle in order to keep it in balance. Start sharpening by using the coarse file and pressing into the blade edge with significant pressure as you run the file along the blade. Take your time and maintain the angle as you give each individual blade about 20 passes with the coarse file.
- 5). Switch to the smooth file and finish sharpening the blade in the same manner as you used the coarse file. Be sure to maintain that same blade angle as you work.
- 6). Remove the blade from the vice clamps and slide it back onto the shaft on the bottom of the mower. Use a wrench to replace and tighten the bolts, then stand the mower upright and replace the spark plug wire.
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