How to Sharpen a Chainsaw Chain
Chainsaws are a very powerful tool. But they significantly lose cutting power when they become dull or damaged. If your chainsaw is showing any of these signs of dullness, it might be time to sharpen the chain.
Sharpening a chainsaw is a tedious process, but it will pay dividends by allowing you to cut more quickly and safely.
There are two ways to sharpen your chainsaw – manually with a chainsaw filing kit or using an electric chainsaw grinder. Both require some patience technical skill, but, with our helpful guide, you’ll be well on your way to a sharper chainsaw.
Table of Contents
What you will need
A Chainsaw filing kit includes a Round file, File guide, flat file and depth gauge. A bench vice is useful to hold the chainsaw bar during sharpening.
Be sure to put on protective gear (gloves and eye protection) before you begin.
Setting up the chainsaw
Tension the chain on the chainsaw properly to make sure the cutter doesn’t slip while you are sharpening. Use a bench vice to hold the chainsaw bar and make sure your chain can freely turn.
Wipe off any grease or oil from the chain before you begin sharpening.
Parts of a Cutter
Let’s quickly go over the parts of the cutter. Please refer back to this diagram as needed.
Filing The Leading Edge
1. Select The Correct Round File.
The first step is to select the correct round file for your chain. Your cutter will have a code number on the depth gauge or a marking that denotes the chain pitch. Use the chart below to determine the diameter of the round file you will need.
Code Number on the depth gauge
Alternative marking on the depth gauge
Round file diameter
Table 1: Sourced From STIHL Conversion Table
Choosing the correct diameter round file is very important. If you use a round file that’s too large, you might end up filing down your hook or, worse, filing it backwards. If your hook gets filed backwards, the chainsaw won’t cut at all.
Quick tip: Having a file handle for your round file will make the filing process easier.
2. Positioning your file guide
Place your round file in a file guide. A file guide is a simple tool that controls the depth at which you file. Many file guides also help you to maintain a uniform angle.
When you place your file guide on the cutter, make sure it is perpendicular with respect to the chain bar – not angled upward or downward. You need the file guide to rest flat on the bar.
You’ll also need to make sure that you file at the correct angle. Typically, the filing angle is 30 degrees. You can determine the filing angle for your cutter by looking at the laser etching on the top plate of the cutter. Once you have determined the filing angle, make sure the corresponding angle mark on the file guide is line with the chainsaw chain centerline.
Hold the round file such that a quarter of its diameter is above the top plate of the cutter.
3. Start with the most damaged cutter
In order for your chainsaw to function properly, all the cutters must be approximately the same length.
When sharpening your chainsaw, the amount of filing required will be determined by the most damaged cutter, because this cutter will require the most filing to get it back in working order.
By starting with the most damaged cutter, you can determine how much filing is required to sharpen it. Then, you can proceed to file the rest of the cutters to this same length.
If you don’t start with the most damaged cutter, you’ll end up having to rework many of the other cutters in order to get them all to the same length.
Now that everything is set up, it’s time to begin filing. The round file only sharpens on the forward stroke. Lift the file off the cutter on the backstroke to avoid damaging your file. The cutter is sharpened when the cutter has a shiny surface.
File all the cutters on one side of the chain then reposition your chainsaw to file all the cutters on the other side.
Filing the depth gauge
Another part that might need filing is the depth gauge (also called the raker). After filing the tooth of the cutter, the depth gauge might end up higher than the tooth. Use a guide to see if this is the case. Set the guide on the tooth; if the depth gauge is protruding, use a flat file to file it down.
A good way to tell if you need to file down your rakers is by looking at the wood chips coming off when you use your chainsaw. If the chips are very small, you need to file down your rakers.
Be sure to not to file down your rakers too much as this might cause more kick back when you use your chainsaw.
- Keep track of where you began. Use a felt tip marker to mark the first cutter that you sharpen so that you can easily spot when you are done with one side
- Make sure you’re filing at the correct position. Mark the cutter with a felt tip marker before sharpening. After a couple of strokes, check how much material you filed off. If the surface looks shiny, you can continue filing. If there are still marks from the marker left over, check your filing action and make sure you are using the correct file at the correct position
Electric Chainsaw Grinder
Sharpening with an Electric Chainsaw Grinder
There are a variety of chainsaw grinders available today. The instructions below are general guidelines, so be sure to check the user manual of your specific grinder.
- Fasten the electric chainsaw grinder on a bench or other sturdy surface.
- Adjust the vice to the correct top plate filing angle. The proper angle can be determined by looking at the laser etching on the top plate of the cutter.
- Place the chainsaw chain in the vice and ensure that the vice blocking handle is properly screwed in. Make sure the chain is tight and isn’t rotating.
- Adjust the grinder head angle to the recommended top plate angle. The grinder is going to be sharpening your leading edge of your cutter.
- The grinder needs to touch the leading edge of your cutter. Adjust your blocking handle to secure the cutter in the correct location if needed.
- Turn on the grinder and sharpen the first cutter by lowering the arm with the grinder.
- Raise the arm and loosen the blocking handle. Run the chain along the vice to position the next cutter. Sharpen all the left-hand cutting teeth first and then rotate the vice to sharpen the right-hand cutting teeth (or vice versa). In practice, this means you need to sharpen every other cutter and then spin the vice to the correct angle to sharpen the remaining cutters.
- Keep track of where you began. Use a felt tip marker to mark the first cutter that you sharpen, so that you can easily spot when you are done with one side
When to replace your chainsaw chain
Your chainsaw chain should last you a couple hundred hours of use. Maintaining your chainsaw well and sharpening the cutters regularly will help prolong the life of your chain.
If your chain gets rusty, dented or badly chipped, it’s time to replace it. Minor chips can be fixed with sharpening.
Your cutter has small guides stamped onto it. These are safety markers. After sharpening your chain several times, you will start approaching these safety markers. If you sharpen past these markers you risk the chain falling apart. You should replace your chain when you reach these safety markers.