How to Sharpen a Chainsaw
A chainsaw's ability to cut wood comes from the sharp, opposing cutters spaced along its chain. Each cutter is made up of two components: a flat-faced depth gauge that controls the depth of the cut and a dual-profile cutting element. These two profiles (referred to as the top plate and side plate) contain three different angles that, when combined, quickly cut through wood and remove waste. If the chainsaw is no longer chewing through wood like it used to, or if the waste appears more like sawdust than small wood chips, the chain has probably become dull and needs to be sharpened.
While many chainsaw manufacturers offer proprietary sharpening tools that are specific to their brands, most chains can be just as easily sharpened using the following generic sharpening tools:
- A round file sized to match the pitch of the chain. For both 1/4 and 3/8 in. low-profile chains, use a 5/32 in. file. For a 0.325 in. chain, use a 3/16 in. file. For both 3/8 and 0.404 in. chains, use a 7/32 in. file.
- A 6 in. flat file
- A file guide to help you hold the file at the correct height and orientation
- A depth-gauge filing guide
- A stump vise (if you plan to do any sharpening in the field)
- A pair of heavy gloves
Chainsaw Sharpening Steps
If you're working in the field, secure the saw in a stump vise; otherwise, secure the saw in a bench vise on a flat work surface. Place the file guide over the cutter, and lay the round file across the guide within the cutter. Draw the file from inside the cutter to outside using full strokes, sharpening all the cutters on one side of the chain before moving to the other side.
As you sharpen the cutters, the clearance between their cutting elements and the chain's depth gauges slowly becomes smaller. To offset this reduction, you must also file the depth gauges. Some sharpening guides double as depth-gauge guides and are set for the recommended clearance; if yours doesn't do double duty, you can use a separate depth-gauge filing guide.
Place the guide over the chain, making sure its top surface rests squarely on the chain's top plates. Using the 6 in. flat file, stroke from inside the cutter to outside until the depth gauge is flush with the top of the slot. Repeat this sequence until all of the depth gauges are the correct height.
One its chain is sharpened, your chainsaw will be ready for more cutting action. But remember that if you're doing a lot of work in any one day, you may need to repeat this process a couple of times to keep the chain at its sharpest.