More accurate vertical angle calibration for Afinia/Up! 3D printers

I was looking for more accurate vertical angle calibration for my printer, since the included one is so short...but I had no idea how to do it.

I found this video (I didn't create it), which has a great solution and the calculation is explained:

http://www.youtube.com/watch?v=IP5NF1_ySpo

Here is the calculator he used:

http://www.csgnetwork.com/righttricalc.html

If you use the STL attached, use an A value of 125mm. I printed with .4mm layer heights for speed.