Is It Ok To Sharpen Lawn Mower Blades Without Taking Them Off?

Some people enjoy mowing their lawn — being outdoors with the sounds of nature and the smell of freshly cut grass brings them peace. Others, not so much. If you're one of those people who will do whatever it takes to mow your lawn more quickly and efficiently, then you might wonder if you could save time by sharpening your lawn mower blades without taking them off. The short answer is that it can be done, but experts recommend that you remove them.

Some people are concerned that safety might be an issue, but whether you sharpen the mower blades on the machine or off, the first step is the same: disconnect the power source (spark plug, battery, or corded plug). That way the mower can't be started by accident when you're working on it.

There are actually several reasons not to sharpen lawn mower blades without taking them off. It's awkward to stop the blade rotating. It can be difficult to get the correct sharpening angle. There's a risk that metal filings will get into the bearing of the motor shaft and cause damage. Finally, you can't balance the lawn mower blades properly, a step people often forget after sharpening. However, if you really must, then let's look at how it can be done.

There are numerous tools for sharpening mower blades. In this case, you need one that can be taken to the machine. Something basic like a file or sharpening stone would work, or, if you want a powered device, a rotary tool like a Dremel. An angle grinder is an option as well, but is hard to control in the space available.

You'll need to lean the mower on its side and make sure it can't topple. If it's gas, make sure the carburetor is at the top so fuel doesn't leak out. A jack or ramps are needed for riding mowers. Chock the blades with a piece of wood jammed against the deck to stop them moving. Wrap the motor shaft with rags to prevent filings from getting into the bearings. Clean the blade, then get on your hands and knees and sharpen it with whichever tool you have. Be careful to follow the existing angle. If you take too much off of one side, the blades will be unbalanced. You might notice uncomfortable vibrations and an uneven cut. There's nothing you can do about that without removing the blade.

So, while sharpening lawn mower blades without removing them can be done, it is both awkward and inaccurate. Next time you notice the warning signs your lawn mower's blades need sharpening, allow an extra few minutes, take them off, and do the job properly. Your machine will last longer and your lawn will look much better for it.