Sharpening with a Square File
To start sharpening after you’ve gotten your angles lined up, take a file strokes with the file, then remove the remove and take a look at the cutter tooth. There will be some marks where the file has removed some steel. Adjust the file based on what you see. Continue sharpening until the tooth looks as sharp as the one of the reference chain.
After producing the first sharp cutter tooth, it’s time to move on and make the rest of the teeth look the same. The best way to do this is to look at the chain. Counting the number of strokes is only provides a rough estimate, since not all stokes remove the same amount of material.
Each tooth needs to be the same, because this will help ensure a consistent cut. If one tooth is bigger or smaller the others, it will cut off different-sized chunks of wood, causing the chain to chatter and vibrate. This inaccuracy can also make it so the chain cuts crookedly.