All documentation says that tip 0 must be calibrated at the factory defined location, or if it is not use the LA command to move it. What information does the MP use from Tip 0? Offsets from a theoretical machine Zero? If so wherever you put the sphere on the table the offsets will show the deviation from this position. Then as long as the rest of series of tips is done in the same position all is OK? Can someone explain why tip 0 must be cal in the factory position? Thanks..