Restore a Lawn Mower Blade
Outfitted with a grinding wheel, an angle grinder is a great tool for restoring edges on lawn mower blades. If you need a sharper edge than the grinder leaves, follow up with a mill bastard file. To sharpen a lawn mower blade, orient the grinder so that the wheel spins from the body of the blade toward the edge (refer to the arrow on the body of the grinder to determine which direction the wheel spins).
Finally, with the grinder off, rest the grinding wheel against the blade and adjust the angle of the grinder to match the blade’s bevel. This is the position you’ll want to maintain as you grind the edge. Lift the grinder from the edge, switch it on and let it come to speed before moving it into the blade. Stroke the grinder across the work in the direction of the handle rather than grinding back and forth. Then lift it off and repeat, concentrating on holding the grinder at a consistent angle throughout the stroke. It’s easy to overheat a metal blade with a grinder. Overheated metal turns a bluish black or straw color and won’t stay sharp for long.To avoid overheating, apply only light pressure and keep the grinder moving. Also keep a bucket of water and sponge or rag handy and drench the metal frequently to keep it cool.