There are a number of different chain saw sharpeners on the market that will automatically sharpen the chain. Professional quality bench sharpeners, enthusiast level chain sharpeners, and handyman sharpeners. Each of these has their advantages and disadvantages, including price, portability, ease of use, and accuracy.

Professional and enthusiast grinders sharpen the chain when it is off the saw. Guides hold the chain in perfect position while adjustments to edge angle and tilt angle are precisely set up. These systems are very fast and accurate, but of course you need to take your saw, or at least the chain, into your local saw sharpening shop.

The simplest, and in many cases the most practical sharpening tool is a simple hand held round file. You can also add a file guide and depth gauge guide to assist you. Consistency is the key to a sharp chain. The same number of strokes on every tooth, and the exact same direction of every stroke will lead to an extremely sharp chain saw.

There are several types of hand file guides. The simplest type attaches to the round file and allows you to watch the markings on the guide so that you maintain a consistent angle every time you stroke the file. Another type of file guide clamps to the bar and controls the movement of the round file over the teeth of the chain.

The round file needs to match the size of your chain. Most common chain saws should be sharpened with either 7/32 inch or 5/16 inch files. Most round files will last forever if you take care of them properly. Wrap them up before dropping them into your toolbox, and don't use them for picking stones out of the logs.

You can pick up a good depth gauge at most hardware stores. This gauge should be set on top of the chain and used to control how much you need to remove from the guides after each sharpening. After several sharpenings the teeth on your chain will be lower than the guides. You need to take the guide height down to match the height of the teeth on your chain saw.