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How to Sharpen a Circular Saw Blade

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We often find ourselves in situations where our tools aren’t in tip-top shape. Whether it’s from overuse, poor storage, or accidental drops, sometimes our tools don’t perform as well as they should. Dull saw blades are a perfect example of that.

When a circular saw blade doesn’t cut in the same way as it used to, it’s either time to replace or sharpen it. The cost of a new circular saw blade can be quite expensive so sharpening on a regular basis can end up saving you quite a bit of money.

Why Circular Saw Blade Sharpening is Important

Cutting with a circular saw should be an easy task, depending on the type of wood you are cutting. A dull blade can affect your cuts in many negative ways including:

Sawdust flying in the air as man uses his circular saw
  • Making it harder to push through the cut
  • Burn marks on the wood
  • Jagged cuts when trying to follow a cut line
  • Chipping or tearout on your cuts

In addition to the effect on the wood you are cutting, a dull blade heats up faster, possibly warping and damaging the circular saw blade. When a blade warps it will need to be replaced.

Circular Saw Blades you can Sharpen at Home

Steel circular saw blades are the only types of blades we would recommend that you sharpen at home. It is possible to sharpen carbide-tipped blades, but the process and tools needed makes the process so complicated that it is very easy to ruin the blade.

Different Methods of Sharpening a Circular Saw Blade

There are a few different methods of sharpening circular saw blades. Some methods take a lot of time to set up but produce quick results, some require the purchase of expensive equipment, and others use simple tools but take a little longer.

Homemade Sharpening Jigs

Some users have had success with creating a homemade sharpening jig on their workbench and letting the table saw do the work. If you do not need to sharpen your circular blades on a regular basis, we feel this is not worth the effort.

Automatic Sharpeners

There are automatic circular saw blade sharpeners available for purchase. They will get the job done faster than doing it manually, but there can be a lot of drawbacks. The less expensive sharpeners can be hard on the teeth, making them wear out faster. Also, they can overheat the blade, or even worse, lose the correct teeth angle.

Sharpening With a Dremel

A Dremel hand tool with a diamond wheel attachment can produce very good results, but only after practice. With the high cutting power of the Dremel and attachment, it is very easy to cut the saw tips at an incorrect angle.

Sharpening With a File

Person holding a circular saw blade

Our favorite, and recommended, way to sharpen a circular saw blade is with a diamond file. The control available is much higher than other methods, and the possible damage from a fast rotating wheel is not a problem. Our instructions below will be based on using a file to sharpen your circular saw blade.

Tools Needed to Sharpen A Circular Saw Blade

  • Circular saw blade
  • Table vise or clamp
  • Sharpie or other felt pen
  • Diamond file

How To Sharpen A Circular Saw Blade

Here are the steps to sharpen your circular blade.

  1. Unplug the saw or remove the battery
    Safety first! Be sure to remove all power sources from the circular saw so that it will not accidentally turn on.
  2. Remove blade
    To make things easier, remove the blade from the saw. Most manufactured circular saws have a hex wrench attached to the side that is used to unscrew the blade attachment. Follow the manufacturer’s instructions. Note the direction the teeth are facing.
  3. Clamp the blade vertically in the table vise
    Generally, the blade clamped down with the teeth facing toward you will be easier to work with. If the teeth facing away works better for you, feel free to mount it that way.
  4. Mark the first tooth with a sharpie, felt pen or piece of masking tape
    Any way you can mark the first tooth is fine. This is an important step so you will know when all the teeth have been sharpened.
  5. Check teeth alignment
    Check in which direction the teeth are angled. If they are all angled in the same direction, you’ll be able to sharpen the entire blade in one pass. If half are angled in one direction and the other half to the other side, two passes will be necessary.
  6. File the first tooth
    Placing the file flush on the tooth, drag it back and forth approximately 3-4 times. At this point, check if the tooth is sharp. If not, repeat the process with the same amount of strokes and check again. Once the tooth is sharp, remember the number of strokes that it took to sharpen the first tooth.
  7. File the rest of the teeth
    Move on to the next tooth and file it the same number of times as the first one. Once 2-3 teeth have been sharpened you will need to re-mount the circular saw blade so the unsharpened teeth are on the top. Repeat this process until the you have reached the initial Sharpie mark.
  8. Attach the blade back on the circular saw
    Once sharpening is complete, remove the saw blade from the vise and re-attach it to the saw, following the manufacturer’s instructions. Be sure that the teeth are pointing in the same direction as they were when you removed it. This will normally be with the teeth facing forward.
  9. Test the sharpened blade
    Test the refreshed circular saw blade on a piece of scrap wood. If the performance has not improved, check for any warping or other damage to the blade.

Other Factors to Consider

Sometimes when a circular saw is not cutting as well as it should be, a dull blade may not be the problem.

Circular saw blades in need of sharpening lying on saw dust

Dirty Circular Saw Blades

A circular saw blade can get dirty very easily. Tree sap, paint, compressed wood, and regular dirt can build up on the teeth, reducing their cutting power and creating rough cuts.

Before putting the effort forward in sharpening a blade, remove it and clean using a wire or plastic brush and some household cleaner like Simple Green.

Warped Circular Saw Blades

The heat generated by cutting through tree limbs or thick pieces of wood can create a lot of heat. This heat can possibly warp your saw blade.

Even a slight deformation can seriously affect the performance of your saw, creating slight wobbles, uneven cuts, and control problems. Replace your circular saw blades at any sign of warping, deformation, or damage.

Old Rechargeable Batteries

If you have a rechargeable circular saw, the batteries that power it do not age very gracefully. Over time, rechargeable batteries lose the amount of power they can store and put out.

If your saw seems to be slowing down, consider replacing the batteries if they are removable. If the batteries are not removable, you may need to purchase a new circular saw.

Conclusion

Sharpening a circular saw blade is not a difficult proposition, and the tools needed are very basic. Steel saw blades are the easiest to sharpen, while carbide tipped circular saw blades take specialized tools and knowledge to sharpen without damaging them.

Be sure to keep your saw blades at peak performance by keeping them sharp and ready at all times.

An expert at home repair, remodel, and DIY projects for nearly 40 years. His first experience came in completely restoring an antique home. Completely redone from the inside out, and restored to its original form, the home is a featured design by renowned Southern California Architect Cliff May, considered to be the father of the California Ranch Home. Now Dennis spends his time on fine woodworking projects and tool comparisons.