Sharpening Metal Blades - Echo SRM - 311 Operator's Manual

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SHARPENING METAL BLADES

Of the three styles of metal blades that are approved for use on the
ECHO Brush Cutter, only the 8-tooth blade can be sharpened as an
operator maintenance item. The clearing blade and 80 tooth blade
require professional service.
Before sharpening, CLOSELY inspect blade for cracks (look at the
bottom of each tooth and the center mounting hole closely), missing
teeth, and bending. If ANY of these problems are discovered, replace
the blade.
When sharpening a blade, always remove the same amount of material
from each tooth to maintain balance. A blade that is not balanced will
cause unsafe handling due to vibration, and can result in blade failure.
Sharpening 8-tooth Blades
Tool required: Flat file (preferred).
Electric grinder (if special care is used)
Round (rat tail) file for gullet (radius)
IMPORTANT
If an electric grinder is used, use care not to overheat teeth. DO
NOT allow tips/tooth to glow red or turn blue. DO NOT place
blade in cooling water. This will change the temper of the blade
and could result in blade failure.
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 until
all 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 and
blade failure.
3. After sharpening teeth, check each tooth radius for evidence of a
square (sharp) corner. Use the round (rat tail) file to renew the
radius.