Lawn Care: How to Sharpen Your Lawn Mower Blade

Posted by: on June 9th, 2012 | 2 Comments
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How dull does the blade in your razor have to get before you stop shaving with it? Chances are, not very. A dull blade causes nicks and skin irritation – an altogether unpleasant experience. Change to a new, sharper blade, and your skin practically throws you a party in return.

Lawns aren’t much different in that regard. Grass responds differently to a sharp, clean shave than it does to a ragged cut. A dull blade may do the job of trimming off the tops of grass leaves, but it does so by essentially chewing its way across your yard. This is why it’s good to know how to sharpen your lawn mower blade. When it comes to lawn mower maintenance, this might be the most important task of all.

 

You may have noticed that you’re more prone to illness when you’re stressed out. To the best of our knowledge, the emotional life of grass is pretty limited, but grass is a plant, and plants respond to physical crises in much the same way that humans and animals do – often by getting sick.

To avoid giving your lawn the sort of nervous breakdown that could make it susceptible to disease, keep an eye out for dulling mower blades. If you discover that your blade has gone dull, take the following steps to give it back its edge.

How to sharpen your lawn mower blade

Skill level: Intermediate

Time needed: 30-60 minutes

Tools needed:

If your blade is dull but in otherwise good condition, you can sharpen it using an ordinary table vice and metal file. You might want to take the mower outside to remove the blade, to avoid any spills in your garage while working on the underside of the machine. Mark the bottom side of the blade before you remove it to avoid putting it on upside down after sharpening it. An upside down blade will simply lash your grass without cutting it.

Before you perform any maintenance on your mower, be sure to disconnect the spark plug or remove the battery. It’s a good idea to clamp the blade before turning the bolt. Using the right wrench for the bolt size, remove the blade and tighten it into the vice.

Start out by using steel wool to remove any rust spots. Then run the file along the blade’s edge, matching the original bevel, until you’ve achieved the desired sharpness. A razor sharp edge will dull quickly; an edge the sharpness of a table knife will cut well without requiring you to sharpen after every cut.

When you have the edge you want, try balancing the blade from the center. If it lists to one side, sharpen the opposite side to more evenly distribute the weight. Before you reattach the blade, take this opportunity to clean out and wipe down your mower’s undercarriage. Be sure not to undertighten the bolt, as a loose blade will vibrate and may ultimately damage your mower.

For badly nicked or curled blades, or blades that have altogether lost their beveling, you may need a bit more power. If you’re not quite ready to replace the blade altogether, you may be able to sharpen it using a bench grinder. First run the blade perpendicular along the grinding wheel to smooth out the irregularities, then again at an angle to sharpen. If you’re not quite ready to invest in a grinder of your own, check your local service shop to see if they’ll sharpen the blade for you.

Performing this simple maintenance once every three or four cuttings will ensure that your lawn is getting the crispest cut possible.

Take a look at more DIY projects here on The Home Depot blog. 

 

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  1. Kitmondo says:

    An early warning tip for spotting dull mower blades is the grass itself. If you see a discoloration (graying usually) in the grass, it’s a fairly accurate sign your blades aren’t sharp. Like the article says – if you’re stressing out the grass it’ll get sick.

  2. Charles T. smith says:

    Good article. Very precise instructions for shapening a blade.