A correctly sharpened chainsaw chain passes through wood with little downward force from the sawyer. Dull, chipped or damaged chains require extra time and effort for the sawyer to complete the cutting task. Chains need regular and frequent sharpening to continue to cut efficiently. Use only the proper file size for the Stihl chain.
Chainsaw Round Files
Stihl chainsaws, like all saws, require filing from a specialized round file. Unlike regular metal files, these files use special groove and bump patterns across the length of the file. This pattern allows the file to reach into and file the rounded hook of the chainsaw's cutter. Files are designated as saw chain files and can be purchased at any Stihl authorized dealer or chainsaw store. Buy a large box of the necessary files as they tend to wear out and need replacing regularly.
Each chainsaw chain, including those on Stihl saws, uses a specific set of measurements to classify the different types of chain. The measurement related to file size requirements is the chain's pitch, which measures the distance between three consecutive rivets (the tie straps holding the links together); divide this number by two. The most common chainsaw chain pitches are 3/8 and .325 inches. The pitch helps determine the size of the cutters and the distance between them.
Round File Size
To properly file and sharpen the teeth on a Stihl chainsaw chain, you will need to get the pitch of the chain. With the pitch of the chain, you can match this number in inches to the diameter of the required round file size. Every Stihl chainsaw model may require a slightly different pitch chain. As an example, a 3/8-inch pitch would require a round file with a diameter of 5/32 inches, or 4.0 mm can be used.
Filing the Chain
The correct file size will ensure too much or too little metal isn't taken off during sharpening. However, the sawyer will still need to ensure the proper angles and depth of the chain are set. These angles also vary widely from chain to chain, but some newer chains have a stamped line on top of them to indicate the filing angle. Depth gauges, the metal stubs in front of the rakers, will also need to be filed with a flat file. Use file guides and gauges if you are inexperienced with filing procedures.