How To: Sharpen a Chain Saw

A chain saw with a dull, poorly maintained chain won't cut cleanly or effectively—and it's a safety hazard to boot. Follow these guidelines to sharpen a chain saw sharp and keep your trusty tool in good working order.

How to Sharpen a Chainsaw


Like any other tool in your arsenal, a chain saw must be properly and consistently maintained in order to perform effectively. Of course, you can hire a professional to sharpen your chain saw, but most do-it-yourselfers can handle the job on their own, saving some money in the process. So if you’ve noticed that your chain saw no longer cuts as easily and cleanly as it once did, read on to learn how to sharpen your chain saw and keep the tool in good working order.

Chain saw maintenance requires a basic understanding of the tool’s component parts. The models owned by average homeowners typically include the following:
- Engine
- Drive mechanism
- Guide bar
- Chain

Different chain saws operate slightly differently and have different maintenance requirements. Study the manual that came with your chain saw to understand the needs of your specific model. That said, it’s almost invariably true that every part of a chain saw either must have or would benefit from lubrication. Besides occasionally inspecting the motor and chain, confirm on a regular basis that there’s a sufficient quantity of oil in the tool’s reservoir. Also check the guide bar, which holds the chain in place. It can become twisted or bent during use. Avoid problems by ensuring the integrity of the guide bar before you start up your chain saw, each and every time. Even while you’re working, it’s wise to occasionally spot-check this crucial part of what is, after all, a powerful and potentially dangerous tool.

How to Sharpen a Chainsaw - Detail Blade


Sharpen the Chain Saw
There are two approaches to sharpening a chain saw. You can handle the task by means of an electric sharpener—and if you fell trees frequently, electric sharpeners are an indispensable convenience—or you can accomplish the same result manually, using a combination of muscle, sweat, and sharpening files. Electric sharpeners are used mainly by tradesmen, so these tips focus on the manual method, which is more accessible to DIYers.

The chain comprises a series of teeth. You are going to need a file that precisely matches up with the size of an individual tooth in the chain. For reference, the most common sizes are 3/16″, 5/32″, and 7/32″.

Once you’ve obtained a file of the correct size, begin work by thoroughly cleaning the chain, removing all oil, dirt, and debris. (Depending on the condition of the chain, mineral spirits may be either essential or excessive.) Look closely at the chain as you’re cleaning it. If any of the teeth are damaged, the chain may be unsafe to use, in which case you should repair it (if possible) or swap in a new chain.

For best results, you need to firmly stabilize the chain saw before attempting to file the chain. Some choose to place the chain saw in a vise, with the clamps holding the guide bar in such a way that the chain can rotate freely. Alternatively, you can enlist a helper to keep the tool steady while you work.

Locate the shortest cutter blade on the chain (the cutters are the ones with flat tops). This is where you should begin sharpening. If all the cutters are the same height, then you can start with any tooth on the chain, but remember to mark—with a pencil, marker, or even nail polish—the first one that you sharpen.

Set the file into the notched section at the head of the cutter. Holding the file at an angle—the same angle at which the notch was initially ground or most recently filed—slide the file across, twisting it somewhat so as to create friction. From that initial cutter, proceed to file every second cutter around the chain. Now reverse the saw and proceed to file each of the teeth that you left alone in the course of your first pass. When you’ve finished, the flat tops of all the cutters should be more or less precisely the same length.

Finally, inspect the depth gauges (these are the curved links between the cutters). Each depth gauge, or raker, should be shorter than the adjacent cutter. If you find a depth gauge whose height exceeds that of the closest cutter, file down the raker so that it sits about 1/10″ below the height of its cutter counterpart.

Now that you know how to sharpen a chain saw, bear in mind that the more frequently you use the tool, the more often it’s going to need maintenance. In fact, if you are using the chain saw for hours on end over the course of a day, you may need to pause at some point in order to restore the chain’s sharpness. Also, be aware that chain saws are likely to show wear in some areas more than others. Pay special attention to the area near the tip of the saw, particularly if you often use it for cutting tree limbs.