How To Sharpen Lawn Mower Blades Without Removing Them

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If you have a riding lawn mower instead of a push mower, it may be because you prefer to cut the grass from a seated position, but the more likely reason is that you have a large yard. That means the blades have to cut a lot of grass, so you may need to sharpen them often. Unfortunately, removing them is a hassle. Wouldn't it be great if you had a tool that allowed you to sharpen the blades without taking them off? 

There are several tools for sharpening mower blades while they are still attached to the machine. If you have a drill, you can do as YouTube user The Hobby Farm Homestead did and purchase a grinding attachment specifically designed for lawn mower blades, such as the UF Sharp Lawn Mower Blade Sharpener. Its beveled 120-grit grinding stone polishes at just the right angle. All you have to do is run the tool a few times back and forth along the edge of the blade to hone it.

After sharpening the blade of his riding mower and doing a test mow, The Hobby Farm Homestead noted that the blade cut well, but some of the grass was still ragged. He concluded that this tool was good for maintaining the blade, but there is no substitute for taking the blade off the mower and sharpening it with a bench grinder. 

One of the problems The Hobby Farm Homestead noted while sharpening his blades was that a drill's rotational speed isn't fast enough to sharpen as efficiently as possible. On the plus side, the drill attachment was inexpensive, and since you can use it with a cordless drill, you can stop your mower and sharpen the blade as soon as you see that it isn't cutting well.

The problem of low rotational speed is one you can overcome by using a rotary tool attachment rather than a drill attachment. A rotary tool is a smarter way to sharpen blades. It spins at a much faster rate than a drill, and attachments are available specifically for sharpening lawn mower blades. There's no shortage of cordless models on the market, so a rotary tool can come with you into the field just as easily as a drill. 

Even better than a rotary tool with a sharpening attachment is a rotary tool designed specifically for sharpening lawn mower blades, such as the Sharp Pebble Cordless Lawn Mower Blade Sharpener, which has a solid 4.0 rating on Amazon. This tool has an adjustable grinding angle, so you can use it on non-standard blades like mulching blades, and a maximum rotational speed of 30,000 rpm. Compare that with 2,000 rpm for a standard drill. With that much grinding power, it's easier to oversharpen the lawn blade than undersharpen it, so keep that in mind when using it.