Circular saws are an invaluable part of the woodworker’s kit, and they allow you to make a range of straight cuts quickly and easily. However, any circular saw is only as good as the blade you put in it, and with a blunt blade, your saw will be unable to make clean, accurate cuts.
While it’s easy enough to simply replace a blunt blade, you can save yourself a bit of cash by sharpening your blade yourself. It’s not difficult, doesn’t take too long and will greatly extend the life of your blades. If you’re interested in trying, here’s how to do it.
If you want a preview, here’s a good video showing you how it can be done.
Table of Contents
Different types of blade
Before you sharpen your circular saw blade, you need to know which type you have. More specifically, you need to know how the teeth are arranged.
Ripping blades usually have the teeth aligned all in the same way while crosscutting blades have the teeth aligned in an alternate top bevel pattern.
Below, we will talk about how to sharpen a ripping blade first – and after that, we will tell you how to go about sharpening a crosscutting blade.
You also need to know what your blade is made of. Less expensive blades are usually made of what’s known as high-speed steel (HSS). If you have an HSS blade, you can sharpen it using a regular file.
However, if your blade is carbide-tipped, things are more complicated. These blades are designed to be extremely hard and durable, and a regular file won’t work. You will need a diamond file – or you may simply prefer to take it to a professional to have it sharpened.
Sharpening a regular ripping blade
To sharpen a ripping blade, you will need a bench vice, a file and a marker pen.
Whichever type of circular saw you have, a sidewinder or a worm drive saw or even a mini circular saw, make sure it is turned off and not connected to a power source before removing the blade.
Take the blade and fasten it in the vice. Make sure you don’t clamp it too tightly or you will risk damaging the blade. If you bend it, it will no longer be able to cut in a straight line and will be worthless.
When the blade is fixed in place, take the marker pen and mark the first tooth you are going to sharpen. This will allow you to see when you have sharpened all the teeth and will help you avoid double-sharpening them.
Take the file and sharpen the first tooth. The best technique is to file in one direction only with a forward filing motion. If you file backwards and forwards, you will wear the file down much faster and won’t be able to use it anymore.
After a few strokes, you will be able to see clean steel on the blade. This means the tooth should now be sharp and you can move onto the next one.
Rather than loosening the vice and rotating the blade for each tooth, you can probably sharpen three of four of the teeth before you rotate the blade.
Continue all the way around the blade until you come to the tooth that you marked with the pen. When you reach that tooth, the blade is sharpened and ready to go. You can now remove it and put it back into your saw.
Sharpening a crosscutting blade
The main difference between a ripping blade and a crosscutting blade is that crosscutting blades often have teeth with alternating bevel angles. This means that alternating teeth need to be sharpening in alternating directions.
It’s just as easy to sharpen one of these blades. You follow the same basic steps, fastening the blade in the vice and marking the first tooth with the pen. The only difference is that when you sharpen the teeth, you have to sharpen every second tooth.
When you have gone all the way around the blade, you then need to remove the blade from the vice, put it back in the other way around and sharpen the other set of teeth in the other direction.
When you have finished sharpening the second set of teeth, you can then remove the blade, put it back in your saw and continue using it as normal.
Can you use an automatic sharpener?
You can also use an automatic sharpener to sharpen your circular saw blades. This technique is much faster but is hard on the edges and probably won’t give you such a good result.
Automatic sharpeners can also overheat and sometimes they will lose the correct angle as you are working.
While using a hand file to sharpen your blade manually might be more time consuming, it will usually give you a better result. Furthermore, some people even enjoy the activity of sharpening a blade manually, finding it relaxing and even meditative.
How to know if your blade needs sharpening
How can you tell when your circular saw blade needs sharpening? The simple way to tell is if a blade is struggling to cut through a piece of wood that normally it should make light work of.
Make sure the blade is the correct type for the wood or other material you are trying to cut, and if it is still having a hard time, it could be a good indication it’s time for a session with the file.
If you don’t sharpen a blunt blade, it will cut with a rough finish, it will make the motor work harder, causing it to burn out faster, and will also have an increased risk of “biting”, making the work more dangerous.
However, dull blades can still be used – they are fine for making very rough cuts, for demolition work or cutting wood that might have nails in.
Sharpen your blades to extend their lives and save some money
Sharpening your blades yourself doesn’t take too much time and is a great way to extend your blades’ lifespans while also saving yourself a bit of cash. It’s not difficult and doesn’t require any specialist equipment so it’s something anyone can try themselves at home.
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