Can you help me align the base ?

[Johannes @ Robots in Architecture]

That very much depends on the application. For high-accuracy milling I usually calibrate the XYZ values of a long and a short tool (the higher the difference in length the higher the accuracy) and then use the vector to calculate the right ABC values.
I can send you the code, but to get you started you could also just send me the XYZ values of a short and a long tool and I will send you the ABC values back.

Best,
Johannes