Circular Saw Depth-Of-Cut Formula

Do unto others 20% better than you would expect them to do unto you, to correct for subjective error.

— Linus Pauling, Nobel Prize winner in both Chemistry and Peace.


Introduction

Figure 1: Milwaukee 6.5 inch Battery-Powered Circular Saw (source).

Figure 1: Milwaukee M18, 6.5 inch diameter, Battery-Powered, Circular Saw (source).

I recently bought a battery powered, 6.5-inch diameter, circular saw from Milwaukee. I REALLY like this saw. I have been using it at my cabin in Northern Minnesota, a place where dragging around electrical cords is painful. This saw has quickly become one of my workhouse tools.

One initial concern I had with this saw had to do with the reduced depth of cut that I would get with a 6.5-inch diameter blade versus a 7.25-inch diameter blade. I decided to calculate a table of depth of cut values versus the angle of the saw blade. I will keep this on my phone so I always know my depth of cut.

It has turned out that the 6.5-inch blades more limited depth of cut has not been an issue at all. Overall, this is one of the best tool purchases that I have made.

Background

Figure 2 shows the manufacturer's specifications for the saw's depth of cut at 90° and 45°.

Figure 2: Manufacturer's Specification for the 6.5-in Depth of Cut.

Figure 2: Manufacturer's Specification for the 6.5-in Depth of Cut.

For comparison, I have included the depth of cut specifications for the 7.25-inch version of this saw. I prefer the 6.5-inch saw because it is significantly smaller and lighter. However, sometimes you need a bit more depth of cut and 7.25-inch is needed.

Figure 3: Depth of Cut for a 7.5-inch Version of This Saw.

Figure 3: Depth of Cut for a 7.5-inch Version of This Saw.

Analysis

Graphical View

Figure 4 shows the saw blade at three common angles: 90°, 60°, and 45°. The drawings also show the depth of cut. The depth of cut for the 90° and 45° cases agrees with the manufacturer specifications shown in Figure 1 – the 60° case was not specified by the manufacturer.

90deg 60deg 45deg
Figure 4(a): 90° Cut Angle. Figure 4(b): 60° Cut Angle. Figure 4(c): 45° Cut Angle.

Analysis

I used a bit of trigonometry to derive a formula for the depth of cut. I show this formula and my depth of cut table in Figure 5.

Figure 5: Table of Depth of Cut Values.

Figure 5: Table of Depth of Cut Values.

Conclusion

I now now my saw's depth of cut for a large number of possible cutting angles. I will keep this table on my phone so that I always have it near.

 
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One Response to Circular Saw Depth-Of-Cut Formula

  1. Great post with graphical explained. I am not a professional circular saw user but use the Makita 5007MGA tool for general work. I think everyone needs to have such tricks using a circular saw. Safety is first.

     

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