Thread: My bevel angle calculations

Originally Posted by BeBerlin

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That's why in the spreadsheet the complete angle = 2*(arcsin ((B/2)/A).
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...we will end up with a "measured spine after taping" which will be 2*0.15=0.3mm thicker than before. This brings the formula to: 2*(arcsin ((B+(2*tape_tickness)/2)/A).

The first equation is correct, but there is a small flaw in the second equation. You are correct in saying the width of the spine changes giving you the extra term to be added to B, but it shouldn't be 2*tape_thickness since you are only considering half the angle in this triangle, thus only 1*tape_thickness, the thickness of the other half of the tape is already accounted for in the 2* in the beginning of the equation before the arcsin term. Also, A in the second equation is not the same A as in the first one. When you add tape, you are not only increasing the thickness of the spine, but also the distance (the hypotenuse "A") from the edge of the bevel to the spine.

So you could the formula: 2*(arcsin ((B+tape_tickness/2)/A), but the A in this formula would have to be the measured distance from the spine w/tape to the bevel. Note that I took out the 2* coefficient in front of the tape_thickness variable.

If you look at some of the previous posts between Ben and I, we were discussing this problem. But, it was then accounted for.

I hope what I wrote makes sense. I can always write up what I mean by hand and scan it if I need to be more clear. It's almost 2 AM, so it may not be the clearest.

P.S. I like to write the symbol for inverse sin and tan, basically just a little superscript -1, but it's same as writing arcsin or arctan. It's just a personal preferrence for some reason....Helps me remember that it's essentially an inverse function.