A Bush Hog blade looks like a giant lawn mower blade, the difference being the thickness and length. It is used for clearing rough areas of small trees, bushes and thick undergrowth. Because of the way it is built and the function it is made for, a Bush Hog is not a precision cutting instrument. The blades spin at a very high rate of speed, and at times it pulverizes whatever it comes into contact with instead of cutting it. To that end when sharpening, standard do-it-yourself tools are all you'll need.
Lift the Bush Hog up and lean it against any immovable structure like a barn, garage or out building. This will expose the underside and depending on the size of your Hog, there will be two or three blades.
Put on your safety glasses and gloves, then turn the angle grinder on.
Grind each blade of the Bush Hog, starting at the point where the edge begins. From the factory there will have been a 45-degree edge ground into the blade. Follow that angle with your grinder, grinding off as little as possible on each pass.
Move the grinder back and forth at roughly the same angle as the original edge. This does not have to be exact, just close enough so that it looks good with your eye.
Turn the blade to the other side and repeat the process, grinding down the blade and following the same angle. Each blade under the deck will get the same grinding treatment.