How to Sharpen Lawn Mower Blades
As we mentioned in our Grow Greener Grass article, you can always take your lawn mower blades to a local hardware store or a big box store like Home Depot to have them professionally sharpened. You can also buy a new blade (it’s good to have a spare).
However, sharpening the lawn mower blades yourself is a simple process and only requires a few inexpensive tools. We demonstrate how in this video tutorial, using the blade from the Redback 40V Li-Ion Mower, which we reviewed here.
Tools you will need:
- Vice to hold the blade
- Bionic Heavy-Duty Work Gloves
- Corona Mill Bastard Cut File with Handle, also comes in a set of three, with round and flat files.
- If you want a smaller sharpener (usually used on pruners), try this
- Retractable Diamond Sharpening Rod or a Sharpening Stone
Sharpening the lawn mower blade(s):
Should you sharpen using a bench grinder? You could, but they’re a little too powerful. We recommend sharpening by hand, so that you’re able to more closely control the sharpening.
Using a vice makes sharpening the blades much easier, as you’re able to hold them in place. We recommend that you wear gloves, as the blade will be very sharp, and metal filings will come off the blade as you sharpen it.
Lawn mower blades are only sharp on one side (unlike, say, a knife). So be sure to only sharpen the chiseled side. As Jack says in the video, it’s similar to a chisel that you would use for woodworking.
Using your flat file, begin filing, following the contour of the blade. File into the direction of the cut (see the video for a demonstration of this). You’ll notice that the blade will start to become silver. If there are any detents in the blade (which there usually are for mulching purposes), you can rotate your file.
Continue to file until the blade is sharp.
How sharp is too sharp?
You want the blade sharp, but not too sharp. If it’s razor sharp, any sticks you might encounter will put a ding in your blade. You can make it that sharp, but then drag a sharpening stone over the top of the blade. To remove burrs, use a diamond sharpening rod by running it over the top of the blade.
Balancing the lawn mower blade
While only one side of the blade is sharp, you want to be sure that the chiseled part of both parts of the blade is sharpened to an equal amount, so that your blade is balanced. If your blade is not balanced, the mower will start to vibrate.
Last update on 2018-08-16 / Affiliate links / Images from Amazon Product Advertising API