Patent ID: 8166664

Claim:
A method of aligning arm reference systems of a multiple-arm measuring machine ( 1 ) comprising at least two measuring units ( 4 , 5 ), each having a movable arm ( 11 , 18 ), and a measuring tool ( 6 , 7 ) movable by said arm ( 11 , 18 ) in a respective measuring volume (M 1 , M 2 ); the measuring volumes (M 1 , M 2 ) of said measuring units ( 4 , 5 ) having an intersection (I), and defining as a whole a machine measuring volume (M) equal to the combined measuring volumes (M 1 , M 2 ) of the individual measuring units; and the method comprising the steps of: fitting at least one reference member ( 25 ) to the arm ( 11 ) of at least a first measuring unit ( 4 ); qualifying each of said measuring tools ( 6 , 7 ) of the respective measuring units ( 4 , 5 ); aligning the reference systems (X,Y,Z; x,y,z) of said measuring units when setting up the machine ( 1 ); and periodically updating alignment of said reference systems by detecting said reference member ( 25 ) by means of at least another measuring unit ( 5 ); the reference member ( 25 ) being moved into a number of positions at said intersection (I) by the first measuring unit ( 4 ).