Finding accelerometer location inside a phone

[Haversin]

My approach would have been to measure the distance of the sensor to the axis using the "centripetal force" experiment several times at different orientations relative to the spindle and then finding the intersection of the resulting circles. 

I like this idea, it's sounds like a 2 D version of how GPS works. For the first position/orientation I'd use middle right side of phone against the spindle (same as above). For the second I tried the middle top of the phone against the spindle and when I turned on the turntable the end of the phone hit the tone arm support  no damage done  I will need to use a platform to rise the phone above the tone arm support.