A file is one of the simplest and cheapest tools for sharpening lawn mower blades. Suitable file types include 10- to 12-inch mill, flat, and hand files, provided they have a coarse cutting profile known as “bastard cut.” The three file types listed vary in how they taper in thickness and width. One type may suit you better, but it comes down to personal preference, and all three will sharpen your mower blades.
It’s best to place your dull lawn mower blade in a vise or securely clamp it to a sturdy workbench to sharpen it. You’ll also want to remove old grass clippings, dirt, and surface rust with a wire brush before you begin. Now look at the existing blade angle where the manufacturer sharpened it before. You’ll want to match that angle with the file, so position the blade to make it as easy as possible.
The file only cuts when pushing it away from you. Start with the forward end of the file near the base of the mower blade’s cutting edge and firmly push the file away from you and along the cutting edge. It takes some pressure, but there is a balance between forcing it and letting the file do the work. Keep a count of the number of strokes it takes to restore the edge and match it on the other side. Any significant nicks or severely degraded blade shapes will require a new blade.
