If you’ve ever wondered if you can use a smaller blade inside your circular saw, then you’re not alone – many of us have had the exact same thought when faced with a blade that’s smaller than the saw’s default blade diameter.
While you might be thinking why you would ever want to use a smaller blade than the manufacturer recommended one there are a few common situations where you might want to do this.
Let’s say you need to cut some granite or concrete. The specialty diamond blades designed for this task are typically sold in smaller than normal sizes. If you’ve got a 7 ¼ inch circular saw, the nearest blade diameter would be 7”.
Another scenario would be you’ve got a 10-inch compound miter saw, and you want to make a few precise cuts in laminate flooring. The only fine-tooth blade you have lying around is a 7 ¼ inch size.
The short answer to the above questions is that you can generally use a smaller blade in a circular saw – within reason. Of course, there will be some drawbacks and changes in performance, especially when you size down by a significant margin.
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What are the Implications of Using a Smaller Blade?
Using a smaller blade than the manufacturer recommended one can be a lifesaver if you don’t have the right sized blade on hand, but what effects does this have on your saw’s performance?
Cutting Depth
The most obvious effect of using a smaller blade is that the saw’s cutting depth will be decreased.
If you’re using a 7-inch blade in a 7 ¼ inch saw, or a 9-inch blade in a 10 inch saw, then the effect will be minimal. However, toss a 7 ¼ inch blade on a 10-inch saw and you might not be able to cut through your workpiece.
Keep in mind that if you swap your blade out for a smaller size you’ll need to make adjustments to achieve the right cutting depth. The cutting depth indicators on your saw will no longer be accurate and you’ll need to account for the difference between the blade you’re using and the saw’s normal blade size.
Blade Geometry
Whenever you’re planning on using a blade other than the one recommended by the manufacturer, it’s important to consider the blade geometry. Blade geometry refers to a saw blade’s teeth shape and angle, material, and kerf.
You’ll want to match the blade geometry of your blade to the saw you’re planning on using. Blade geometry can differ significantly depending on the type of saw you’re talking about.
For example, miter saw blades typically have a low tooth angle, which prevents an overly fast feed and makes for a smooth non-aggressive cut. Blades designed for ripping with a circular saw or table saw typically have a high tooth angle, which results in an aggressive cut and a fast feed rate.
Another thing to consider is that smaller saw blades are typically thinner and have narrower kerfs. Kerfs are the term for the width of the saw’s teeth.
There’s a lot to unpack when it comes to blade geometry, and you can certainly get lost in the weeds here, but the important thing to keep in mind is to try and match the blade with the saw type. Using the wrong blade for the saw type can produce poor results, and may even be hazardous.
Rotation Speed
Rotation speed is another important factor to consider. Saw blades typically have a maximum rotation speed, which is measured in revolutions per minute (RPMs). You’ll usually find this info stated on the blade’s packaging.
Just like with blade geometry, when choosing a saw blade you want to ensure the max RPM of your saw is greater than the one stated on your saw blade.
When you use a smaller saw blade than the manufacturer recommended one, while the RPMs remain the same, the actual distance the blade will travel will be less. This is because a larger blade will cover more distance per revolution.
That means the smaller blade will be under less stress and can often handle the higher RPMs. You can see this when you compare a typical 5,500 max RPM of a 12” saw blade to a 10,000 max RPM of a 6 ½ inch blade.
Can you Use a Bigger Blade in a Circular Saw?
While you can certainly use a smaller blade in a circular saw – as long as you keep it within reason, you might also be wondering if you can use a bigger blade in a circular saw.
The answer is generally this is not a great idea. A larger blade will put excess stress on the motor, and may not have enough strength to provide the cutting power at the tooth you need.
You may also have issues with stress placed on the arbor from the additional wobble created by a larger blade. This could theoretically lead to the arbor failing and the entire saw failing catastrophically.
