Disconnect Power: The most critical first step is to remove the battery pack from your cordless circular saw. This eliminates any risk of accidental startup while your hands are near the blade.
Clear Work Area: Set your saw on a stable, clean surface. Positioning the saw so the blade is easily accessible will make the process smoother.

Removing the Old Blade

Once your saw is secure and depowered, you can proceed with removing the dull or damaged blade.

Locate the Spindle Lock: Most circular saws feature a spindle lock button designed to hold the arbor (the shaft that the blade mounts onto) stationary. Press and hold this button firmly.
Loosen the Arbor Bolt: Using the specialized blade wrench that typically comes with your saw, loosen the arbor bolt. It's important to note that the arbor bolt on many circular saws has a reverse (left-hand) thread, meaning you'll turn it clockwise to loosen it.
Retract the Blade Guard: Gently push back the lower blade guard to fully expose the blade.
Remove the Bolt and Washer: Once the arbor bolt is loose, carefully remove it along with any outer washer or flange. Keep these components in a safe place, as they will be reinstalled.
Carefully Remove the Old Blade: Lift the old blade straight off the arbor. Even a dull blade can be sharp, so handle it with care.

Installing a New Circular Saw Blade

Proper installation is crucial for the performance and safety of your saw.

Clean the Arbor: Before placing the new blade, inspect the arbor and any inner washers. Clean off any sawdust, grime, or debris to ensure the new blade sits flush.
Orient the Blade Correctly: Place the new blade onto the arbor. The teeth should always point in the direction of the saw's rotation, which is typically towards the front of the saw (where the blade exits the base plate during a cut).
- As demonstrated in the YouTube video "How to Change a Circular Saw Blade" (from 1:00 to 1:37), it is essential that the arrows printed on the blade and on the blade guard are aligned to face the same direction. This ensures correct rotational direction for cutting.
Reinstall the Washer and Bolt: Place the outer washer or flange back onto the arbor, followed by the arbor bolt.
Snug and Secure the Bolt:
- The video reference instructs you to "reinstall the bolt and washer and snug it up." This means hand-tighten the bolt until it feels firm.
- Next, engage the spindle lock again and use your blade wrench to fully tighten the arbor bolt. Remember, for a reverse thread, turn it counter-clockwise to tighten. Ensure it's very secure to prevent the blade from loosening during operation, but avoid over-tightening which could strip the threads or damage the saw.

After installing the new blade, perform a few checks to ensure everything is in order.

Blade Guard Check: Release the lower blade guard and confirm that it retracts smoothly back into its protective position.
Reinstall Battery: Carefully reinsert the battery pack into the saw.
Test Run: Before making any cuts, briefly activate the saw to ensure the blade spins freely without any wobbling, vibration, or unusual noises.
Blade Type: Always use a blade specifically designed for the material you intend to cut (e.g., wood, metal, masonry) and verify that its arbor size and maximum RPM rating match your saw's specifications.

Issue	Possible Cause	Solution
Arbor bolt won't loosen	Incorrect turning direction (e.g., not reverse thread).	Confirm the thread direction; try turning in the opposite direction (counter-clockwise to loosen).
New blade wobbles or vibrates	Blade not seated properly, or arbor bolt not sufficiently tightened.	Remove the blade and re-seat it, ensuring it sits flush against the arbor. Re-tighten the arbor bolt securely.
Saw struggles to cut with new blade	Incorrect blade orientation or dull blade (if reused).	Verify the blade arrows align with the saw's rotation. Ensure you're using a sharp, new blade.
Blade spinning in wrong direction	Blade installed backward.	Ensure the arrows on the blade and the saw's blade guard are facing the same direction.