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 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.
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.
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.
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| 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.
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.
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.
I'm looking at buying a circular saw and came across this page, super helpful thank you. Might I suggest simplifying your function a bit?
sin(90deg - Angle) = cos(Angle)
and
cos(90deg - Angle) = sin(Angle)
I shall make that improvement. Thank you for improving my blog site.
mark
You can equip your circular saw with a variety of blades that can literally rip through anything from concrete blocks to bricks and wood. They can even be ordered in various sizes and all have a specific cutting depth, with the cutting capacity directly that is related to the blade diameter.
Appreciate your analysis. I am about to buy a new saw and this information is most helpful.
Great post! Well done
I am a 60 year old man who taught science, math and shop for 30 years
This is the first time I have every been compelled to post on the Internet
Buying thus tool today for all the reasons you listed and
already downloaded your chart for reference
Nice thinking
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Thanks for this beautifully written post with great knowledge. I learned a few things that will hopefully help me going forward.
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I'm a carpentry student looking at purchasing this exact saw and needed to know if the depth of cut at 45 degrees was sufficient for 2x material. Thank you!
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