A value of 8192 is 1g must be subtracted using the correct orientation vector.
But this can also be used for offset and gain calibration for each orientation on initialization and saved in flash upon startup. One can also repeat at different temperatures.
Dropping device onto spring ( with soft materialk on surface and with same compression as gravity
i.e. same stop depth as drop height and analyzing +1g, 0g, -1g and back to +1g from collected data.
This can be averaged and used to calibrate offset and gain errors to eliminate all major sources of error and gravity.
Beware of noise and prevent as much as possible and use averaging.
Beware of calibration errors and orientation errors. √(x² + y² +x²) should equal 8192 before gravity is removed when stationary and = 0 after gravity vector is removed.