Tools for Sharpening Chain Saws

Filing Guide and Round Files

A filing guide and round file shape the cutters on a chainsaw. In the sharpening process, the filing guide clamps onto the chain bar and allows you to guide the movement of the round file across the cutters. To perform a proper sharpening, make consistent filing strokes in in the right direction; the filing guide aids in this process.

The round file used in sharpening needs to fit the filing guide as well as the chain on the chainsaw. Most cutters need either a 5/32 inch or a 7/32 inch diameter file, specification for size of file needed can be found in owners manual or in the instructions that came with a new chain.

Before sharpening the cutters, tighten the chain on the bar until you have left no slack in the chain. Though too tight for cutting purposes, a chain this tight makes sharpening easier. Tighten the chain by loosening the nuts that hold the bar in place and turning a standard screw between the bar and body of the saw clockwise. Retighten the nuts that hold the bar once you have tightened the chain.

Clamp the filing guide to the middle of the bar on the top side. Some filing guides have metal fingers for supporting chain links during filing; position the tips of these fingers between the cutters and the rivets on the chain. With the filing guide in place, adjust the angle of the filing guide to match the angle of the edge of the cutters -- typically an angle 25 degrees to 35 degrees from the chainsaw's bar. After setting the angle,insert the file into the guide for the sharpening process.

A depth gauge guide and flat file allow you to adjust the depth gauges on a chain saw. You need only complete this process every third or fourth sharpening. To perform this task, place the depth gauge guide where it straddles two side-by-side cutters, leaving the depth gauge protruding from an opening in the center of guide. Use a small flat file to knock off any part of the depth gauge that extends beyond a slot in the depth gauge guide. Repeat this process until you have adjusted all the depth gauges. After removing the depth gauge guide, use the flat file to round the flattened tops of the depth gauges to make the gauges run easier over wood.

When filing, count the number of strokes it takes to make the dullest cutter have a sharp edge; use this number on all the other cutters. Cutters alternate direction every other cutter on the chain; therefore, when filing, file every second cutter and then turn the filing guide around and make appropriate adjustments to duplicate the setting.

Replace files after five or six sharpening sessions for optimal results. To maximize use of files, do not leave files unprotected in your toolbox to bang against other tools, but rather wrap the files in clothes for storage. Additionally, before putting your files away, apply a coat of lightweight machine oil to protect against rust.