To keep a chainsaw cutting quickly and cleanly, the teeth on the saw chain must be kept sharp. When a chain needs sharpening, it will produce a lot of fine sawdust when cutting, but after it is properly sharpened, the sawdust will be in the form of small wood chips. While a chain can, and should occasionally be professionally sharpened, you can hand sharpen chainsaw chains with a couple of chainsaw files and a filing guide.
Shut off the chain saw and allow the engine and chain to cool.
Insert a round chain saw file into a chain sharpening guide, and then clamp the guide onto the top-centre of the chain saw bar.
Slide the chain so that one of the teeth whose point is on the opposite side of the bar from your body is directly under the file in the guide.
Adjust the angle of the guide to match the angle of cutting edge of the tooth. Ease the file down into the saddle of the tooth, and push the file forward until you reach the handle of the file. Lift the file out of the tooth and retract the file toward your body, before settling the file back into the tooth's saddle and pushing forward for another stroke. Continue for six to eight strokes, or until the entire cutting face of the tooth is clean and shiny. You should only file with forward strokes; never grind while pulling the file toward your body.
Lift the file out of the tooth, and slide the chain forward to the next tooth on the same side of the bar. Repeat the filing strokes with this tooth, and each subsequent tooth on the same side of the bar. Use the same number of strokes with each tooth.
Remove the file guide from the bar, and rotate the chain saw 180-degrees. Replace the file guide on the centre of the bar, and place one of the unground teeth from the opposite side of the bar under the file. Adjust the angle of the file guide to match the angle of the teeth, and proceed to grind each of the teeth on the opposite side of the bar from your body with the same number of push-strokes you used on the previous teeth.
Remove the sharpening guide from the bar, and lift the round file out of the sharpening guide.
Position the sharpening guide across the tops of two adjacent teeth, so that the rear tooth's depth gauge is protruding through the depth gauge slot in the guide. The tooth's depth gauge should be slightly higher than the guide. File the depth gauge down until it is even with the top of the guide. Then, move to the next two adjacent teeth and repeat until all depth gauges are at the same height.