Things You'll Need
10-inch mill file
Razor sharp grass shear blades easily cut through the thinnest grass with a single pass, so you can achieve perfect edges on your garden borders or trim ornamental grasses to uniform shapes. The fine cutting edge wears out with habitual use, exposure to elements and lack of care, which leads to ragged grass tips that leave the grass susceptible to disease. You must maintain the factory bevel when sharpening grass shears for them to work properly. Blades can be sharpened manually with a mill file or scissor sharpeners.
Secure the grass shears in a table vise with one of the blades facing upward. The lower end of the factory bevel should be positioned closest to your body with the beveled edge moving upward and away from you. If you can't manipulate the shears so the second blade is out of the way, remove the pivot nut with a wrench to separate the two blade-handle sections.
Position the 10-inch mill file against the blade at the tip of the grass shears. Tilt the file up or down to align it with the factory bevel angle.
Push the file forward across the blade to file away a bit of the blade metal. Maintain the bevel angle as you move the file.
Reposition the file slightly down from the first position. Push the file across the blade. Repeat this process along the length of the blade. Return to the starting position to make a second pass, repeating along the length of the blade. Repeat until you achieve a sharp edge.
Lock the second blade into the table vise. Sharpen the second blade from tip to base, following the factory bevel as a guide. Reattach the pivot nut to connect the pieces, if necessary.
Rub motor oil along the exposed metal on each blade to prevent rust. Open and close the blades to check for proper operation. If you detect any friction, apply motor oil at the points where the blades intersect and to all moving parts.
Remove the pivot nut with a wrench. Separate the two blade-handle sections of the grass shears.
Position the first blade handle with the blade edge facing straight up. Hold it in position with your non-dominant hand, or use a table vise.
Align the sharpening surface of the scissor sharpener on the base of the blade. This is a V-shaped notch that straddles the blade. The sharpening surface must be aligned with and touching the factory bevel.
Pull the sharpener from base to tip of the blade in a single motion while applying slight, even pressure. Perform this action 10 to 12 times or until you achieve a razor sharp edge. Repeat this process with the second blade.
Reattach the shear blades and tighten the pivot nut. Apply motor oil along the sharpened edge and to any moving parts where you detect friction.
A 10-inch mill file might also be labeled as a mill bastard file or simply a bastard file.
Never attempt to sharpen grass shears with electric grinders because they grind away too much metal too fast, making it impossible to achieve a perfectly sharpened edge along the entire blade.