Patent ID: 7249421

Claim:
A method of taking a measurement of a workpiece feature with a coordinate measuring machine, the coordinate measuring machine comprising a table, first and second guideways associated with the table, a bridge movable on the guideways, a drive element associated with the first guideway for driving the bridge, a carriage movable on the bridge, a probe mounted to the carriage, and a scale operative to permit scale readings indicating a position of a portion of the bridge along the first guideway, the method comprising: (A) obtaining hysteresis error data for the bridge; (B) moving the bridge in a first direction, and, at a first bridge position, taking a first reading from the scale, the carriage being a first distance from the scale; (C) moving the bridge in a second direction, and, at a second bridge position, taking a second reading from the scale, the carriage being a second distance from the scale; and (D) determining a value of a measurement of the workpiece feature based on at least: the first reading from the scale; the first distance of the carriage from the scale; the second reading from the scale; the second distance of the carriage from the scale; the first direction; the second direction; and the hysteresis error data, wherein no readings from any additional bridge scales are used to determine the value of the measurement of the workpiece feature.