How to sharpen a chainsaw

You have probably heard it said that a dull knife is a dangerous knife. It is doubly so when you are talking about chainsaws. A dull chainsaw is more likely to bind, kickback and sling the chain off of the cutting bar. Since maintaining a sharp chainsaw is a matter of safety, it is important to know how to sharpen your chainsaw. We’ll give you step by step instructions on how to sharpen a chainsaw as well as some tips on how to keep your chainsaw sharp, but before we do, let’s answer a few common questions about sharpening chainsaws.

Common Questions About Sharpening a Chainsaw

When should I sharpen my chainsaw?

The best way to know when your chainsaw needs to be sharpened is by taking a look at the waste material that comes out of your saw cuts. In general, if your saw is sharp, you should see mostly chips in the waste material. Whenever you see a lot of sawdust instead of chips, you’re cutting with a dull chainsaw.

In addition to examining the waste material there are other ways of knowing that your saw is dull. A sharp chain cuts with little-added force or pressure on the bar. If you find yourself straining or trying to force the saw, then your saw is probably dull. If your chain is properly tensioned and binding and kicking the cutter bar back at you (kickback), then stop cutting and sharpen your chainsaw.

What tools do I need to sharpen my chainsaw?

Having the right tools makes sharpening a chainsaw a pretty simple task. To manually sharpen a chainsaw you need four tools:

  • A round file. Your round file will need to be specifically sized and suited to the diameter of the cutter diameters on the chain. They typically come in 5/32, 3/16 and 7/32 inch diameters. DO NOT think that a rattail file is the same thing. Using a rattail file will ruin the cutters.
  • A file guide. The file guide helps to hold the file at a uniform depth instead of judging depth freehand.
  • A flat file. The flat file is for touching up and resetting cutter depth.
  • A depth gauge. This tool allows you to gauge whether you need to touch up or reset cutter depths.

Be certain to have to proper tools available and don’t even attempt to sharpen your chainsaw if you do not. You can do more damage than good without the right tools.

Do you have to sharpen your chainsaw with a manual file?

No, you don’t. Some might think that it is a bit tedious and labor intensive to sharpen a chainsaw using a manual file. For those who prefer to allow a machine to do most of the heavy lifting there are plenty of ways to machine sharpen a chainsaw as well. Keep in mind that there are advantages and disadvantages to both manual and machine approaches and we’ll discuss them later in this article.

Understanding Chain Anatomy

Before sharpening a chainsaw you need to become familiar with the anatomy of a chainsaw chain. Chainsaw chains are fairly complicated when compared to most other cutting blades and you really need to know what you are looking at and what you’re doing to properly sharpen them.

Every other link on a chainsaw chain has a cutter link. Each cutter link is either a right-cutter (inside facing) or a left-hand cutter (outside facing). These cutters are in a semi-circle shape with an edge and a specific diameter. Included with every cutter link is a depth gauge, which looks a little bit like a fin or a pointed tooth. The depth gauge tends to be a hair shorter than the tip of the cutter and helps to determine how deep the cutter bites into the wood.

Here is an image of the links on a chainsaw chain.

links on a chainsaw chain

When sharpening a chainsaw, you will use a file and gauging tools to help maintain a consistent and proper relationship between the guide fins as well as honing the edges of the cutters.

Steps to Sharpening a Chainsaw

Step 1: Stabilize the Saw

Before you can begin sharpening your chainsaw you will need to stabilize the saw as well as the chain to make it easier to hold the saw and chain in place while you sharpen it. Out in the field, this will mean finding a level place where your saw can sit without wobbling, like on the tailgate of a pickup or on top of a large tree stump. In the shop, the easiest thing is to lightly clamp the cutter bar in a vice.

Quick Tip 1:

If you clamp your chainsaw in a vice, be sure to clamp it at the center of the cutter bar rather than the upper or lower edge to minimize the chances of doing damage to the cutter bar.

Quick Tip 2:

In the field, you can cut a saw kerf about half the width of the cutter bar into a log, which is flatted on the opposite side for stability, as a means of holding the cutter bar in place while you work.

Step 2: Stabilize the Chain

In order to sharpen the cutters on your chain, you will need to stabilize the chain so it doesn’t move while you work. In order to do this, you will need to loosen the tension adjustment bolts on the saw and adjust the tension to a point that there is no side to side wobbling of the chain whenever you attempt to move it back and forth between your fingers. Once the chain is properly tensioned, you can tighten up the tension adjustment bolts.

Quick Tip:

DO NOT FORGET to readjust the chain tension on your saw once you have finished sharpening as this level of tension will break your chainsaw’s chain almost the same instant it touches the surface of the wood you intend to cut while in motion.

Step 3: Mark the Chain

You will be sharpening links all the way around the chain, which means it will be pretty difficult to know when you have sharpened all of the cutters on the chain. Since they all look alike, you will want to mark the first cutter so that you will know when you come to the end. A dab of bright paint on the flat surface of the cutter will do the trick.

Quick Tip:

Out in the field, you can wedge a twig or thick shaving between the cutter edge and the gauge fin to mark where you started if you do not carry a paint stick for marking lumber.

Step 4: Place the Guide and File

Proper placement of the guide and file is essential in order to maintain the proper depth consistency of the cutter edges. The guide should be placed between the rivets on the chain. Be sure that the arrows on the guide point in the same direction as the nose of the cutter bar. Also, make certain that you have the proper diameter file in the file guide.

Here is one type of guide and file properly placed.

properly placed file
properly placed file

Quick Tip:

If you picked up your chainsaw secondhand or inherited it and don’t know which file size is right for your chainsaw, take it to a professional and have them properly gauge the file size. Go ahead and have the check the machine over for dangerous mechanical failures as well.

Step 5: Follow the Proper Angle

The guide rollers will keep you from going to deep with your file, but you will need to pay attention to the angle of the top plate on the cutter in order to maintain a consistent angle (typically either 30 or 35 degrees) and properly sharpen the saw. If you are not consistent with your cutting angles, your saw will not cut smoothly and the chain will have a tendency to bind or pull. Additionally, a chain with improper angles will create more dust, which will gum up the motor and chain.

Quick Tip:

Maintain right angles both horizontally and vertically while you work.

Step 6: Steady, Even Strokes

Use your file to cut steady, even strokes. A well-maintained chain will not need more than 2 to 3 strokes on each cutter in order to keep the edge honed. You will want to push the file away from you in order to clear metal chips and debris away from the edge rather than drawing them onto it. To create a consistent cutting edge on all links be sure to use the same number of strokes on each cutter. Don’t re-sharpen cutters you have already sharpened, which is why we marked our beginning point in step 3.

Quick Tip 1:

According to the family handyman, you get the best performance from sharpening if you “count your strokes, and use the same number of strokes on each cutter.”

Quick Tip 2:

Avoid dragging the file back across the cutting edge as this will work against what you are trying to achieve and actually dull the cutter.

Step 7: Rotate the Chain

After sharpening two or three cutters, release the brake in order to allow the chain to be advanced forward. Move the chain forward so that dull cutters are in the same location as the ones you just sharpened, and then reset the brake. Moving the chain forward rather than attempting to work around the chain from various positions will make things a lot more comfortable and a lot more consistent.

Quick Tip:

Moving the chain in a measured and consistent way helps you consistently maintain the same position and angle while you sharpen.

Step 8: Turn Saw Around

Remember that the cutting anatomy of your chainsaw blade has both right-hand cutters and left-hand cutters. Consequently, once you have sharpened all the cutters on one side of the saw, you have to turn the chainsaw around so that you can sharpen the cutters on the opposite side of the chain. You will know when it is time to turn the saw around because you marked your beginning point in step 3. If you only sharpen one side, you will create all kinds of binding and kickback problems that can be dangerous.

Quick Tip:

DO NOT attempt to file both right-hand and left-hand cutters in a single pass. You need to sharpen the opposite side cutters with the exact same consistency as you did the original side cutters. This requires holding your file at the correct angles and using the same strokes.

Step 9: Adjust Depth Gauge Heights

Once you have sharpened all of the cutters, you will want to take a look at the depth gauge heights (the fins on the cuter links). It is important to fine tune or adjust these depth gauges in order for the cutters to actually reach the wood that you are trying to cut. If these gauges are not set correctly, the cutters will either bite too deep into the wood or not cut into the wood at all.

Quick Tip:

Use a gauge depth guide to get a precise depth on every cutter link in order to make your saw run at its very best.

The following video provides a good demonstration of how to sharpen a chainsaw as well as some of the reasons for doing things a certain way.

Manual Sharpening vs. Machine Sharpening

As we mentioned above, there are those who feel like manually sharpening a chainsaw chain is a bit too labor intensive and prefer to use a machine for sharpening. There are others who believe that sharpening by hand provides more consistent results. We’ll take a quick look at the advantages and disadvantages of both and let you decide which way you lean.

Manual Sharpening

Using a file with or without a guide to sharpen the cutters on a chainsaw has both advantages and disadvantages.

Advantages:

  • Can be used in remote locations.
  • Files are inexpensive.
  • More consistency in stroke count on each cutter.

Disadvantages:

  • Slower going.
  • More labor intensive.

Machine Sharpening

Using a machine with or without a guide to sharpen the cutters on a chainsaw has both advantages and disadvantages.

Advantages:

  • Much faster.
  • Less labor intensive.

Disadvantages:

  • Can’t be used in remote locations.
  • More expensive than a file.
  • Less consistency from one tooth to the next.

Tips to Keeping Your Chainsaw Sharp

Tip 1: Watch Where You Put Your Chain

Your chain will become dull faster if you dip it into the dirt, rocks or other hard surfaces while the chain is turning. Keep an eye on the surface beyond your chain and avoid hitting it.

Tip 2: Sharpen Regularly

The rule of thumb is to sharpen your chain every time you refuel. Regular sharpening keeps your chainsaw operating at its very best and makes for less work each time you sharpen. Popular Mechanics says, “you know it’s time to sharpen your chain once you have to apply pressure to the chainsaw as you are cutting.”

Conclusion

Keeping your chainsaw sharp not only makes your saw easier to use, but it is also a matter of safety. A dull chainsaw will bind and kickback both of which are dangerous situations for the user. Our guide has provided you with the tools and information you need in order to keep your chainsaw sharp as well as step-by-step instructions that you can follow next time your chainsaw isn’t performing at its best.

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