Calculate lengths of inner, mid, outer arcs of elbow curve

I know this might be more of a math question, but I figured I would try. Attachment 865106I am trying to figure out the lengths of R3 (Spine length), R2, and R1. I know that D1 equals 6" and that the Center Line Radius is 1.5. I also know that T1 and T2 are both 9" (I don't think these matter though). Can anyone help me? I'm trying to make an excel that will allow me to change the diameter and CLR and give me R3, R2, and R1.

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I assume that the Rn values are just for the arc portions. I also assume that this curve is through exactly 90°.

The circumference at R2 is πd, which is π(1.5)(2). Dividing by 4 gives the length of the arc. Assuming that the radius at R2 is in cell A1:

Formula:

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This could be arithmetically simplified if you wish, but I prefer to show the unreduced form to suggest the original logic.

At this point I think your model breaks. You said that the center line radius is 1.5, and that D1 is 6. If that is correct then this drawing is not at all to scale. In this drawing the center line radius is about twice as big as D1.

But here is the math. Let's say the value of D1 is in cell D1.

For R1

Formula:

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where 6/2 is half of D1, since that is the difference between the center line radius and the inner radius

For R3

Formula:

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similar logic

I had to get rid of the picture to attach the workbook I guess. Strange. I also realize that the "Center Line Radius" should be labeled 1.5 x the diameter which is 6".

Originally Posted by Zimmy242

I had to get rid of the picture to attach the workbook I guess.

You shouldn't have to. I see both all the time.