GRASS TRIMMER /BRUSH CUTTEROPERATOR ' S MANUAL 31SHARPENING METAL BLADESThree styles of metal blades are approved for use on the ECHO BrushCutter. The 8-tooth blade can be sharpened during normal mainte-nance. The clearing blade and 80 tooth blade require professionalservice.Before sharpening, CLOSELY inspect blade for cracks (look at thebottom of each tooth and the center mounting hole closely), missingteeth and bending. If ANY of these problems are discovered, replacethe blade.When sharpening a blade, always remove the same amount of materialsfrom each tooth to maintain balance. A blade that is not balanced willcause unsafe handling due to vibration and can result in blade failure.8-tooth BladeTools required: Flat file (preferred), Electric grinder if special care isused, Round (rat tail) file for gullet (radius).1. File each tooth at a 30 degree angle a specific number of times,eg. 4 strokes per tooth. Work your way around the blade untilall teeth are sharp.2. DO NOT file the 'gullet' (radius) of the tooth with the flat file.The radius must remain. A sharp corner will lead to a crack andblade failure.IMPORTANTIf an electric grinder is used, use care not to overheat teeth, do notallow tips/tooth to glow red or turn blue. DO NOT place blade incooling water. This will change the temper of the blade and couldresult in blade failure.3. After sharpening teeth, check each tooth radius for evidence of asquare (sharp) corner. Use the round (rat tail) file to renew theradius.