To sharpen a chainsaw, use a round file to sharpen the cutting edges on each of the cutters attached to the saw's chain. File your cutting edges at a 30-to-35-degree angle both horizontally and vertically, ensuring that you file each cutter the same number of times. Finally, test your saw to ensure it cuts more effectively: wood chips, rather than sawdust, indicate a sharp chain.
Before beginning to sharpen your saw, ensure you obtain the correct-diameter round file, which must match your chainsaw cutter diameters. Medium-duty chainsaw cutters often measure 3/16, 5/32 or 7/32 inches wide. Keep the chain on your saw and advance it every now and again to make the cutters easier to file. The cutting angles on the cutters reverse every other tooth, so make sure you file your cutters in the right direction.
To save time, some handymen and homeowners use an electric rotary tool to sharpen their chainsaws. Some rotary tools conveniently come with appropriately sized grinding wheels, which work well with common-diameter cutters.
After sharpening your cutters, ensure you examine the depth gauges on your chainsaw's chain. If they protrude above the cutters, file them down until they're flush with the top of your cutters. This ensures you get a good cut each time you use your saw.