How To: Change a Circular Saw Blade

It may sound simple, but a lot of people can get hung up changing saw blades especially if you don’t do it very often. In this post, I’ll walk you through the basic process of how to change a circular saw blade which is one of the most useful tools any DIYer can use.

A nice sharp blade can make all the difference in the quality of your work. I would venture to say that many people don’t change their blades nearly often enough which results in poor or difficult to make cuts and also creates more blade kickback than is otherwise necessary. Just check out the video below to see how dangerous kickback is and why keeping a sharp blade is important.

Every saw is a little different, but the basic premise is the same so don’t be thrown off by the little differences.

step 1: safety first

Check to make sure the saw is unplugged or remove the battery on a battery saw. Do not attempt to change a blade while the saw is plugged in or has a battery inserted. Seriously, let’s keep those fingers!

Gloves are not required but may prevent cuts. The carbide tips on saw blades are sharp and it can be pretty easy to cut yourself, especially if your hand slips when trying to loosen a tight blade bolt.

If you have the manual that came with your saw, it is a good idea to read it. Not only will it tell you how to replace the blade, but it will give you details that are specific to your saw, like which way the blade bolt loosens and tightens or where to find the wrench that comes with the saw.

step 2: remove the old blade

Locate the wrench that comes with the saw. Most corded saws will have an open-end wrench and battery saws will have an Allen wrench. They are sometimes attached to the cord while others will slide into a spot on the bottom or handle part of the saw. 

If you’ve lost yours, you can also use an open-end or socket wrench.  Adjustable wrenches can get the job done as well, but a bit harder to work within the limited space.

Unlock and adjust the base plate to the lowest position to allow as much room to work around the blade bolt as possible. Lock the base plate. The base plate adjustment is what determines the depth of cut. 

Locate the blade lock button or lever usually found on the backside of the upper guard.

While depressing the button, place the wrench over the bolt and turn the blade with the wrench until you feel the blade lock in place. While you continue to depress the button, use the wrench to loosen the bolt and then unscrew it completely and set aside.

Which Way to Turn?

This is the biggest question most people have because on circular saws the old lefty-loosey, righty-tighty rule doesn’t always apply. The bolt will loosen in the same direction the blade rotates when in use.

Usually, on a corded right-hand circular saw, the bolt will loosen counterclockwise. A left-hand saw will loosen clockwise. You can also look for the arrow on the upper or lower blade guard for the blade rotation. Loosen the bolt in the same direction as the arrow.

What if There is No Blade Lock?

Some older circular saws do not have a blade lock or shaft lock. There are two ways to hold the blade in place while loosening the bolt.

The first is to raise the base plate so that some of the teeth of the blade can be pressed into a piece of wood or work table. While pressing down on the saw and holding it in place, follow the steps above to loosen the bolt.

The second way is to clamp the blade in place with some Vice-grips or other lockable pliers while loosening the bolt.

If you find that the bolt is not loosening, but rather turning the motor while the blade remains secure, give the wrench a tap or a quick snap to break the bolt free.

Remove the outer washer and set it with the bolt.

After the bolt and outer washer have been removed, carefully grab the blade and lift it off the shaft and out through the base plate. You may need to rotate the retractable blade guard for more clearance.

step 3: install the new blade

Before installing the new blade, be sure to inspect and remove any lodged debris from the inside of the upper guard. Also, make sure the inner washer, where the new blade will sit, is clean and free of debris.

When picking the right saw blade refer to my earlier post The Everyman’s Saw Blade Guide to find the right one for your project.

Once you have your new blade, look for the arrow on the new saw blade. This shows which way the blade should rotate when installed. Most saws will have an arrow on one of the guards indicating blade rotation. The blade should be flipped as necessary to match up the arrows so they are rotating in the same direction.

In this case, I’m installing the same old blade since this is just for demonstration purposes.

Retract the lower blade guard and insert the blade up through the base plate. Place the blade onto the shaft and make sure it is snug against the inner washer.

Slide the washer onto the shaft. Turn the washer until it drops in place snug against the blade.

Insert and tighten the blade bolt until it is finger tight. Lock the blade by depressing the blade lock button. Use the wrench to tighten the bolt the rest of the way, about 1/8th of a turn.  Do not over tighten.

step 4: Check the Blade and Get to Work

Plug in the circular saw or insert the battery.

While the base plate is still lowered, and the saw held up off of a work surface, pull the trigger, and observe the blade spin.  The saw should feel smooth and the blade should not wobble.

Next, use a piece of scrap wood and do a test cut to check that the blade cuts through smoothly, as expected.

If the saw stops cutting and the shaft spins in the blade, remove the saw from the material, unplug and tighten the bolt more. Adjust as necessary until the saw is moving smoothly and consistently through the material.

That’s it! You’re ready to get back to business now that you know how to change a circular saw blade.