How To Change a Circular Saw Blade

Changing the blade on your circular saw is an essential skill for any DIY enthusiast or professional carpenter. An appropriately sharp blade ensures clean cuts and safe operation of your tool. This guide will walk you through the process of changing a circular saw blade, from safety precautions to proper installation techniques. This Old House general contractor Tom Silva demonstrates the correct and safe way to install a new blade on a portable circular saw.

Safety First: Preparing To Change the Circular Saw Blade

Before you begin the process of changing your circular saw blade, prioritize safety. Taking the proper precautions will help prevent accidents and ensure a smooth blade replacement process.

Disconnecting the Power Source

The first and most important step in changing a circular saw blade is to disconnect the power source. This prevents accidental activation of the saw during the blade change process.

• For corded saws: Unplug the saw’s power cord from the electrical outlet or extension cord.
• For cordless saws: Remove the battery from the saw.

Double-check that the saw is completely powered off before proceeding.

Gathering Necessary Tools

Before you start, make sure you have all the required tools on hand. This will make the process more efficient and reduce the risk of injury from improvising with inappropriate tools.

• Blade wrench (usually provided with the saw)
• Clean cloth (for wiping down the arbor and blade)
• New circular saw blade
• Work gloves (optional but recommended for added safety)

Selecting the Right Blade

Choosing the right replacement blade optimizes performance and safety. Consider the following factors when selecting a new blade:

• Arbor size: The center hole of the blade must fit the saw’s arbor perfectly.
• Blade diameter: Ensure the new blade matches the size of your saw (commonly 7-1/4 inches for portable circular saws).
• Maximum RPM rating: The new blade should be rated for at least the maximum speed of your saw in revolutions per minute (RPM).
• Tooth count and type: Choose based on the material you’ll be cutting (e.g., choose a blade with more teeth for making finer cuts in hardwood).

Removing the Old Saw Blade

With safety measures in place and tools ready, you can now remove the old blade from your circular saw.

Locate the Arbor Lock

Most modern circular saws feature an arbor lock mechanism that simplifies blade removal and installation.

1. Look for a button or switch near the blade housing.
2. Press and hold the arbor lock button.
3. Rotate the blade slowly until you feel the lock engage, which will prevent the arbor from spinning.

Loosen the Arbor Nut

Once the arbor is locked, you can remove the nut holding the blade in place.

1. Locate the arbor nut at the center of the blade.
2. Place the blade wrench on the nut, ensuring a secure fit.
3. Turn the wrench in the same direction as the blade cuts to loosen the nut.
4. Remove the arbor nut and outer washer, setting them aside in a safe place.

Remove the Old Blade

With the arbor nut and washer removed, you can now take out the old blade.

1. Carefully retract the saw’s upper blade guard.
2. Gently remove the old blade from the arbor.
3. Inspect the arbor and surrounding area for any debris or damage.

Installing the New Circular Saw Blade

Now that the old blade has been removed, it’s time to install the new one.

Prepare the New Blade

Before installing the new blade, take a moment to inspect it and ensure it’s ready for use.

1. Remove any protective coating or stickers from the blade.
2. Check for any shipping damage or defects.
3. Verify that the blade’s arbor hole matches your saw’s arbor size.

Position the New Blade

Correct blade orientation is critical for safe and effective cutting.

1. Slip the new blade onto the saw’s arbor.
2. Ensure the blade teeth are facing in the direction of rotation. If you’re unsure, refer to the arrow on the saw’s blade guard.
3. Make sure the blade sits flush against the inner washer or flange.

Secure the Blade

With the new blade in place, it’s time to secure it to the saw.

1. Replace the outer washer and arbor nut.
2. Engage the arbor lock as you did when removing the old blade.
3. Use the blade wrench to tighten the arbor nut securely.
4. Be careful not to over-tighten, as this can make future blade changes difficult.

Special Considerations When Changing Circular Saw Blades

While the basic process of changing a circular saw blade is straightforward, certain types of saws and blades require special considerations.

Worm Drive Saws

Worm drive saws often have a different blade mounting system compared to sidewinder circular saws. Some blades come with a diamond-shaped knockout for use with worm drive saws.

If your saw has a diamond-shaped arbor, you may need to remove the diamond insert from the center of the new blade. To do so, place the blade over two wood blocks for support. Use a hammer and punch to carefully tap out the diamond insert. This allows the blade to fit properly on the diamond-shaped arbor of the worm drive saw.

Left-Blade vs. Right-Blade Saws

The direction in which you turn the wrench to loosen or tighten the arbor nut can vary depending on whether your saw has the blade on the left or right side of the motor.

For saws with the blade on the right of the motor, turn the wrench to the right to loosen. For saws with the blade on the left of the motor, turn the wrench to the left to loosen. Always turn the wrench in the direction that the blade cuts when loosening the nut.

Blade Tightness

Tighten the arbor nut securely, but avoid using excessive force. Over-tightening can make it extremely difficult to remove the blade in the future. A properly tightened blade shouldn’t slip during use but should still be removable with reasonable effort when needed.

Additional Tips and Tricks for Circular Saw Blades

Here are some extra tips to ensure a successful blade change and prolong the lifespan of your saw and its blades.

Blade Compatibility

While most circular saw blades are designed to be versatile, always double-check compatibility with your specific saw model. Some saws may have unique arbor sizes or blade guard designs that require specific blades.

Maintaining Blade Sharpness

Regularly inspect your blade for dullness or damage. Cutting with a dull blade can lead to splintering, inaccurate cuts, and motor strain. Investing in a blade sharpener or knowing where to get blades professionally sharpened can extend the life of your blades.

Using a Blade with a Kerf

The kerf of the blade is the width of the cut it makes. Using a blade with the appropriate kerf thickness for your saw can lead to smoother cuts and reduced wear on the motor. Thicker kerf blades are suitable for heavy-duty cutting, while thinner kerf blades are ideal for precise, fine cuts.

Avoiding Blade Warp

Store your blades flat in a dry area to prevent warping. Warped blades can cause wobbling and inaccurate cuts. Using blade protectors or original packaging can help maintain the integrity of the blade.

Circular Saw Blade Maintenance and Care

Regular maintenance of your circular saw and its blades can extend their lifespan and ensure optimal performance.

Cleaning the Saw

After changing the blade, take a moment to clean your saw. Use a brush or compressed air to remove sawdust and debris from the blade housing. Wipe down the arbor and flanges with a clean cloth. Check that the blade guard moves freely and returns to its closed position.

Blade Storage

Proper storage of your circular saw blades can help maintain their sharpness and prevent damage. Keep blades separated to avoid teeth contacting each other. Store blades in a dry place to prevent rust, and use blade guards or cases to protect the teeth from damage.

Regular Inspection

Periodically inspect your saw and blades for signs of wear or damage. Check blade teeth for chips, cracks, or excessive wear. Ensure the arbor lock and blade guard are functioning correctly. For corded saws, inspect the power cord for any damage or fraying.