Here’s a few clues to look out for that will tell you it is time to sharpen your chainsaw:

• When it is difficult to cut with the saw – this one is pretty obvious. A sharp chain blade should not require a lot of pressure to cut through the wood. If you are using a lot of effort pushing down on the saw to cut with it, it’s time to sharpen the blade.

• You are producing fine sawdust when cutting – a sharp blade should produce regular, square-ish wood chips. If your saw is making a finer dust, it may be blunt.

Sharpening your chainsaw with a file is made easier by the use of a file guide or file holder, which is a simple guide that positions your file at the correct angle and allows you to sharpen the chainsaw teeth at a uniform angle. These are not strictly necessary but are a great idea if you are new to the procedure.

To sharpen your chainsaw, first of all you will want to clamp the chain bar in a bench top vise in such a way that the chain can spin freely. If necessary, use an off cut of wood to support the body of your chainsaw. If you are working in the field a pin vise may be useful – this is a portable vise that can be set into a stump of wood and hold the blade while it is being sharpened.

Tightening the chain in advance will make it easier to sharpen each tooth, as they will be less likely to move while being sharpened. You should start at one tooth and rotate the blade as you sharpen each tooth until you have done the whole chain. It’s not a bad idea to put a small pen or pencil mark on the tooth that you start on so that you know when to stop. Now you are ready to use your small round file of the correct diameter (with or without a file guide) to sharpen each tooth of the chainsaw.

There are several cutting surfaces to pay attention to on the chain blade, with teeth designed to work the cut on both sides of the blade. You will find it useful to sharpen all of the teeth facing in one direction, and then rotate the chainsaw in your vise before sharpening those on the other side. To sharpen each tooth, draw your file across the cutting surface at the same angle as already exists on the tooth. When you are filing with a round file, hold about 20% of the height of the file above the top of the cutting tooth to help maintain the correct shape of the cutting surface (see diagram below). Two to three strokes should be enough to restore an edge to a tooth that has been lightly worn. If the tooth is more heavily worn, more strokes may be required – try to remember how many strokes are required so that you can sharpen consistently.

Chainsaw sharpening - file angle

If using a file guide for sharpening, check your chainsaw manual to find the correct angle for each tooth. If your manual has gone walking a rule of thumb is a 25 degree angle for each cutting tooth, but different models do vary.

Even among those who sharpen their own chain blades regularly, depth gauges are sometimes overlooked. Maintaining your depth gauges is very important to cut safely and effectively.

An alternative to using a file is to use a circular electric chainsaw sharpener – these can be dedicated sharpeners or bits designed to fit into a drill or similar.

Finally, although sharpening your chainsaw with a file or electric chainsaw sharpener will help keep an edge, it is still advisable to have the chain blade sharpened regularly by a professional, who will be able to ensure that each tooth is at the correct cutting angle.

When you choosing an electric sharpener, consider where you will be using it. Some of the smaller units come with battery packs, which allow them to be transported and carried around wherever you use the chainsaw. If you only use your chainsaw at home it might be more convenient to have a mains powered model, which won’t consume batteries and will always be ready for use.

Another point to look out for is whether the sharpener can be used to adjust depth gauges. Many electric sharpeners are designed specifically to sharpen the cutting teeth and have guides which hold the file at the right angle for this purpose alone. You may need another tool to adjust the depth gauges, which is a task that should be done regularly.

Chainsaw depth gauge

The role of the depth gauge is to control the thickness of the chip that is removed by the cutting tooth, which follows behind it. As you can see in the diagram, the chain gauge should be a little below the top of the cutting tooth. This distance is quite small, so a specialized tool is used to get the correct distance. Check your chainsaw manual to find out what your cutting depth should be set to. As a rule of thumb, check the depth gauges every second or third time you sharpen your chainsaw and adjust them at the same time if necessary.

The depth gauge is adjusted by holding the depth gauge tool over the depth tooth, and filing straight across the top of the tooth with a flat file until the tooth does not protrude from the notch in the tool.

Filing the depth gauge tooth will naturally mean that the tooth loses it’s rounded shape. You can use a saw chain tool to measure the height. Once the height is correct, restore the rounded shape using your file. This will stop the tooth from sticking in the cut as you use the chainsaw.

As with the tooth sharpening procedure, rotate the chain around the chain bar and adjust all of the depth teeth equally before you use the chainsaw.