Forgive me if parts of this do not make sense, as I am not sure how to even ask what I want. I wish to learn how to calculate partial circles cut into an object. Example: If I have a round knob already, and I want to cut in shallow radii around the circumference, like above, I need to be able to calculate the width of the circle for a given depth of that circle, or once I know the width I want to cut, what diameter cutter will I need to use to get that width while the depth is less than the radius. In the pic, the radii are very shallow, and definitely not half of the diameter of the circle that radius would be part of. Yes, I realize the pictured knob is not cut, but cast in that shape. I am thinking that once I have the circumference measurement of my knob, I then would split it into sections, like above, there would be 6 notches and peaks. I want wanted all of them to be equal width, with a circumference of 3.141 (for a 2" diameter knob), I would divide by 12, which gives me...