Weekend Project: Sharpen your mower blade

Consumer Reports News: June 02, 2009 05:45 PM

For our second weekend project, we're focusing on the blade of your lawn mower. As mentioned in the first installment of this series, we're running these items early in the week so you can get them on your to-do list early—and perhaps free up time for some R&R this weekend.

If you didn't sharpen the blade on your lawn mower at the start of this mowing season, or if you've been doing a lot of cutting so far this spring, now's the time to hone the cutter. And remember, you should sharpen the blade every year, more frequently if you have rocky or sandy soil. (If you're in the market for a new mower or tractor, read our latest report on this outdoor power equipment, available to subscribers).

A sharp blade not only cuts grass more cleanly but also trims fuel costs by up to 25 percent. Yet more than a quarter of Americans surveyed in our latest poll about lawns admit they've never sharpened their blade. That's a lot of gas money being left on the table not to mention butchered grass blades leading to ugly, unhealthy lawns.

Here's how to remove and sharpen the blade:

1. To remove the blade, turn the mower on its side; tip the mower so that the air filter faces up to keep engine oil from saturating the filter. To prevent a fuel spill, remove the blade once the mower has run out of gas or siphon off the gas. For good measure, remove the spark plug so there's no chance of the blade suddenly spinning to life.

2. Wearing heavy work gloves, secure the blade by lodging a block of 2x4 block between it and the mower deck (shown). Then use a combination wrench to loosen the bolt that anchors the blade to the drive shaft (there might be more than one bolt). If the bolt sticks, hit the handle of the wrench with a rubber mallet or use the breaker bar from your socket set for added leverage. Never be in a position where your hand or arm will contact the blade if the wrench or socket slips off the bolt or nut. Be sure to put the hardware in a safe place until remounting so you don't lose it.

3. Bring your blade into the local hardware store or power-equipment shop, where a sharpening will run you $5 to $10. If you get to the store before it gets too busy, they might be able to sharpen it on the spot, allowing you to get down to the real weekend project: cutting the grass. While you're at the store, pick up a second blade ($15 to $20). That way you'll always have a sharp blade on hand. Check the owner's manual before you head out to be sure you buy the right blade.

You could also sharpen the blade on your own using a metal file or a bench grinder, but it takes a steady hand to hold the blade at just the right angle and balance it without damaging the blade or hurting yourself.

4. When you remount the blade, be sure its cutting edge follows the direction of rotation—the wings of the blade will be oriented up toward the mower deck. If the mower has a cup washer, make sure the cup is facing the blade. Tighten the bolt according to the manufacturer's specifications.

Another good sharpening option is Dremel's Lawn Mower & Garden Tool Sharpener attachment (about $8) is. Peter Sawchuk, our outdoor-power-equipment expert, uses this attachment at our mower/tractor-testing site in Fort Myers, Florida, where we check out several dozen models every year. "I see value in the attachment for homeowners," says Sawchuk, noting that the nylon guide holds the blade at the right angle for maximum sharpness. In Sawchuk's experience, the only drawback to the attachment is that it can't grind out major nicks. You can also get similar drill attachments for sharpening a mower blade. Properly clamping the blade in a stationary position and using two hands to guide the tool will help you get a uniformly sharp cutting edge.

Even if you have to buy the rotary tool—a basic Dremel kit with a compatible model costs about $45 to $100—it will pay for itself in two or three years.—Daniel DiClerico | | Twitter | Forums | Facebook

Essential information: Read our additional tips for saving money while maintaining a lush, healthy lawn. And check out our mowers and tractors buyer's guide.

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