Abstract: A portable blade sharpening apparatus is disclosed which can be used to sharpen blades while they remain attached to their machines. The blade sharpening apparatus is powered by an electric motor and includes a circular grinding stone which is angled on one side in order to match the angle of the blade to be sharpened. The angle of the grinding stone can be varied, depending upon the angle of the blade that is to be sharpened. The blade sharpening apparatus includes a guide bracket having fingers positioned to limit movement of the grinding stone relative to the blade being sharpened so as to prevent accidental contact between the blade and the drive shaft of the grinding stone.