How to Sharpen a Chainsaw

Dull chainsaws are slow—and dangerous

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Introduction

Is your dull chainsaw blade burning and bucking its way through the wood? It's a slow way to cut. It's also a dangerous way to cut. Here's how to sharpen your chainsaw blade and cut more quickly.

Tools Required

  • Depth gauge guide for sharpening chain saw blades
  • Dremel tool
  • Dremel tool blade sharpening kit No. A679-02
  • File guide for sharpening chain saw blades
  • Flat file
  • Round file

Video: How to Sharpen a Chainsaw

A chainsaw’s nasty-looking cutters can scare you into thinking you can’t sharpen the saw yourself. But in about 10 minutes, with the help of a couple of inexpensive files and guides, you can transform your slow-cutting chainsaw into a firewood-cutting ninja. You can sharpen the chain right on the saw and right by the wood you’re cutting. Do it often, and you’ll get years of sharp cutting life from your chain. Here, we’ll show you how to use chain saw sharpeners.

A dull chainsaw blade can cause burning and buckling while sawing through wood, and it’s a slow and dangerous way to cut. Here are some lessons on how to use a chainsaw sharpener from The Family Handyman expert, Bob Tacke.

Project step-by-step (9)

Step 1

Check the Waste to See if it's Time to Sharpen

  • Check the waste material from your saw cuts.
    • Pro tip: Dust means it’s time to sharpen. Chips indicate that the cutters are sharp. 
    • Note: A dull chain is dangerous—it greatly increases the chances of kickback. The chain is more likely to catch in the material and propel the bar up toward the operator. (Read Using a Chain Saw Safely, for more information).
    • Pro tip: Sharpening is easy if the cutters have dulled from normal use. If the cutters are nicked badly from accidental contact with rocks, dirt or objects embedded in trees, you may need to have the chain professionally sharpened or buy a new one.

Check the waste to tell if it's time to sharpen chainsaw

Step 2

Have the Right Tools on Hand

  • Buy four tools for freehand to use as a chainsaw sharpener:
    • A round file that matches the cutter diameter.
      • Note: Popular diameters for medium-duty chainsaws are 5/32, 3/16 and 7/32 inch. Check the owner's manual for your saw's requirements, or use the chain identification number stamped on the drive link. Small-engine dealers and hardware stores have charts to match this number with the right file diameter.
    • A file guide to hold the round file at a uniform depth as you sharpen each cutter.
    • A flat file.
    • A depth-gauge guide for resetting the depth gauges.
      • Pro tip: Don't use a standard rattail file as a chainsaw sharpener. Its tapered diameter and coarse teeth will ruin your chain's cutters.

chainsaw tools: depth gauge guide, flat file, round file, rattail file, file guide

Know Your Chain

Inspect the cutters (saw teeth) on your chain loop. The semicircular cutting edges can be quickly sharpened and reshaped with a round file. A depth-gauge fin in front of each cutter controls how deep the cutter bites into the wood. The angles ground on the cutters alternate between left and right to keep the saw cutting straight.

The cutters have semicircular cutting edges in specific diameters; to sharpen them, use a round file of the same diameter. In front of each cutter is a “depth gauge,” a piece of metal shaped like a shark fin. The depth gauge’s tip is a hair shorter than the tip of the cutter and controls how deep the cutter can bite. After repeated sharpenings, the cutters can become level with the depth gauges—and keep the saw from cutting. It’s easy to lower the depth gauges to the right height with a flat file and file guide.

three parts of the blade that get sharpened on chainsaw diagram

Step 3

Get Ready to Sharpen

  • Engage the chain brake and lightly clamp the bar in a vice.
  • Place the guide between the rivets on the chain, with the arrows on the guide pointing toward the nose of the bar.
  • Follow the angle of the top plate of the cutter; the rollers on the guide keep you from going too deep into the side plate of the cutter.

Step 4

File at the Right Angles

  • Mount your round file in the file guide.
  • Hold the file at a 30- or 35-degree angle (check your saw's cutters) to the bar horizontally and at a right angle vertically.

how to file chainsaw blade diagram

Step 5

Stroke Away from Your Body

  • Cut a 2-inch deep kerf in a log and rest the saw bar in it to secure it while sharpening.
  • Place the file and file guide into a cutter on the top and near the end of the bar.
  • Mark the top of this cutter with a felt-tipped pen to indicate where you began using a chainsaw sharpener.
  • Line up the file with the factory-ground angle on the cutter.
    • Note: This is almost always 30 or 35 degrees. Most file guides have 30- and 35-degree angles etched on their upper side to help you preserve the angle as you file.
  • Make a stroke, maintaining the proper angle on the cutter, parallel to the ground and away from your body.
    • Note: You'll feel the guide riding on top of the cutter and depth gauge. The first couple of strokes on a dull cutter may vibrate your hand a little.
  • Using steady, even strokes with the file, give each cutter 5 or 6 strokes until the face of the cutter is shiny silver.
    • Pro tip: When you feel a burr along the cutter's outer edge, the cutter is sharp.
    •  Pro tip: Count your strokes, and use the same number of strokes on each cutter.

sharpening chainsaw by hand: stroke away from body

Step 6

Look Through the File Guide

  • Look through the file guide to line up the cutter with the file.
    • Note: You’ll feel the file nest into the cutter.
  • File every other cutter and then move to the other side of the bar to sharpen the rest.

sharpening chainsaw by hand: look through file guide

Step 7

Advance the Chain

  • After sharpening a couple of the cutters, release the chain brake.
  • Rotate the chain forward to expose more cutters to sharpen.
    • Pro tip: Wear gloves when you advance the chain. However, while filing the cutters, you may find you have a better “feel” for the contact between the file and cutter if you work barehanded.
  • Reset the brake and sharpen the new section.
  • Keep repeating this step until you've sharpened one side of the chain.

Step 8

Sharpen the Other Side of the Chain

  • Continue sharpening cutters until you reach the one you marked.
  • Move to the other side of the saw bar and sharpen the opposite-angled cutters, again using the same number of strokes per cutter.

Step 9

As You Work: Check Depth Gauge Heights

  • Check the height of the depth gauges with the filing guide each time you sharpen.
  • When they protrude above the guide, file them flush with the flat file.

Check depth gauge heights on chainsaw

More Sharpening Tips

  • If your saw pulls to the side when cutting, it's because the cutters on that side are sharper than those on the other side. To keep your saw cutting in a straight line, be a fanatic about filing each cutter with the same number of strokes and the same amount of pressure.
  • Cutters can be sharpened up to 10 times or more before the chain needs replacing. If your cutters are worn unevenly after a few sharpenings, a professional can regrind them to uniform shape.
  • If you use the same chain for a few years, then buy a new one, the new one won't mesh smoothly with the sprocket and bar. It'll cause rougher cutting and faster wear on the saw. Bob Tacke, chainsaw expert, advises: “Buy two extra chains and switch off among the three occasionally. This way all the components of the cutting train—bar, sprockets and chains—will fit together and prolong the life of your saw.”
  • File guides that clamp to the bar will ensure that you file the same angle on each cutter. They take a little longer to use, but they restore the cutting edge to the exact factory-ground angle, so there's less chance you'll need to have your chain reground by a professional sharpener.
  • When in doubt, take your chain to a pro. A pro will use a power chainsaw sharpener that resembles a mini-compound miter saw to precisely regrind each cutter to a uniform depth and cutting angle.