3 Ways to Sharpen a Circular Saw Blade? (Easy Techniques)

Last Updated on August 28, 2022 by Barry Gray

Whether you’ve worn down your favorite circular blade or bought some inexpensive used blades, sharpening circular saw blades is a great way to extend the life of high-quality circular saw blades.

There are a few different ways to sharpen a circular saw blade.

Depending on your level of comfort and the equipment you have available, you can have success with any of them, although some are certainly faster than others.

Preparing the Blade

No matter what technique you use, you need to prepare your blade before you can sharpen it. This preparation will look similar across all techniques, so pay attention and feel free to customize it to your needs.

First, you’ll need to remove your circular blade from the saw. Make sure the saw is unplugged, and then either use a wrench to loosen the blade or press the switch to release it if one is available.

Once the blade is free, you can place it in a secure position for sharpening. If you are using a hand-sharpening technique, you can clamp the blade to a flat surface. If you’re using the diamond blade technique, you’ll want to place it on a flat jig on your table saw’s surface.

It’s a good idea to examine the blade before you begin sharpening it. If the blade is dirty or corroded, it’s a good idea to clean the blade before sharpening it. This can also help reveal any more serious issues with the blade, such as chipping or cracks. 

You should also note the type of blade you’re sharpening. If all the teeth are pointing the same direction you’ll be able to sharpen them in one pass, but more complicated tooth arrangements will require multiple rounds of sharpening.

Diamond Blade Sharpening

sharpening circular saw blade with a table saw

For this technique, you’ll need:

  • One table saw
  • One continuous-ring diamond blade
  • One jig (doesn’t need to be anything fancy)
  • Safety glasses and gloves
  • Dull circular saw blade (as many as you have)

The fastest way to sharpen your circular saw blade is by using a table saw with a diamond blade. This technique requires the most equipment, but it can have your blade sharp in just a few minutes.

You should also know that this technique is best used on carbide-tipped blades, since cheaper and older blades might not be worth the time and resources it takes to sharpen them with this method.

This technique will only work if the diamond blade you use is thinner than the gullets between the teeth of the blade you’re sharpening. If you’re looking to sharpen a blade with especially narrow gullets, you may need to use a manual sharpening technique instead of this faster method.

This technique is also much easier on simpler sawteeth. More complicated teeth like combination teeth can be harder to sharpen and take significantly more time to sharpen well. A manual technique may be more appropriate in those cases.

First, install a continuous-rim diamond blade in your table saw. Although these are an additional cost, you can sharpen your own saw blades many times with one diamond blade, so it will end up saving you significant amounts of money if you wear out your saw blades regularly.

Then you can turn the table saw on and begin sharpening. In order to sharpen your blade, you need to fit the diamond blade between the teeth of the dull blade. Then, you can push the tip and front of the tooth against the diamond at the side of the saw blade.

Make sure to match the angle at which you’re grinding your sawteeth to the teeth’s original angles. Then you can push the teeth against the diamond blade, grinding away the dull edge and creating a new, sharper one.

File Sharpening

sharpening circular saw blade

For this technique, you’ll need:

  • One file
  • Table clamps
  • Tape or marker
  • Safety glasses and gloves
  • Dull circular saw blade (as many as you have)

File sharpening is a much slower process, but it allows for more individual precision with the sharpening process. It also requires less expensive equipment than the diamond blade sharpening technique, especially because most woodworkers already have a file on hand.

It’s worth noting that file and sandpaper sharpening may not be appropriate for carbide blades. While steel blades are soft enough that these techniques work well, carbide blades are exceptionally hard and can only be sharpened quickly with commercial diamonds like those found on continuous-rimmed diamond blades.

You need to begin your file sharpening process by marking your starting tooth. By marking that tooth, you know exactly when you’re finished and don’t risk over-sharpening sawteeth you’ve already worked on.

To begin, hold the file against the first sawtooth you plan on filing. Take a note of the tooth’s angle, and match it with your file. Then you can start filing the tooth in long, smooth strokes. Complete four strokes, backward and forward, all matching the tooth’s original angle. 

After those strokes, check the tooth’s sharpness. If you’re satisfied with it you can move on, but if you aren’t, pay attention to the exact number of strokes required to get the tooth sharp.

When you move on to sharpening the rest of the teeth, file each with the exact same number of strokes. This will make sure that the saw blade is equally sharp around all of the teeth and avoid any uneven cuts.

If you’re keeping your blade in a clamp to hold it still while you sharpen, you might want to loosen the clamp and rotate the blade after sharpening three or four teeth. This can depend on the size of the teeth and your exact position, but it’s important to stay comfortable while you work.

Sandpaper Sharpening

For this technique, you’ll need:

  • High-quality sandpaper
  • Oil (or other wood lubricant or lapping fluid)
  • Scrap wood
  • Table clamps
  • Tape or marker
  • Safety glasses and gloves
  • Dull circular saw blade (as many as you have)

First, you’ll want to find or cut a small piece of scrap wood. It should have a pointed edge that can fit in the gullets between the sawteeth but be large enough to fit comfortably in your hand. Glue your sandpaper around the wood tightly, so that you now have a sanding stick you can fit between your blade’s sawteeth.

Now, you should oil the sandpaper with your lubricant of choice. This isn’t strictly necessary, but it prolongs the life of your sandpaper significantly, which will save you from needing to replace it repeatedly as you work your way around the blade.

Next, you need to mark the first tooth you plan on filing. Once it’s marked, you can begin sanding it. Depending on the sandpaper’s grit and the force with which you’re sanding, it can take anywhere from five to ten strokes with the sandpaper to fully sharpen the tooth.

Make a note of the exact number of strokes it took to sharpen the tooth. While this technique is less exact, so the number of strokes can vary from tooth to tooth, it should give you a general idea of how many strokes you’ll need on the rest of the teeth.

Check your sandpaper every time you finish sharpening a tooth. The metal saw blade may wear through it quickly, so you should make sure you aren’t trying to sharpen with worn-out sandpaper. You should also check for its lubrication, re-oiling it as needed.

After you’re finished sharpening the teeth, you should check the sharpness by cutting a piece of wood with the blade. You should immediately see the difference between how it used to cut and how it does now. If you don’t notice a difference, examine the technique you used and attempt to sharpen them again.

Final Thoughts

Sharpening a saw blade can make the difference between finishing a project with high-quality work quickly, or leaving messy edges and working too slowly. It can save you from multiple trips to buy a good replacement, not to mention the cost of buying a new one. 

It’s also a skill you can develop and offer to other woodworkers in your area. Either through networking or selling sharpening as a service, it can be a great supplement to your hobby or career. 

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Barry Gray

Hi, I’m Barry. I’ve loved woodworking and bringing things back to life for more years than I care to remember. I hope my passion for tools comes across loud and clear in everything you read here on The Tool Square.

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