Abstract: A reference block 30 attached to a housing 20a is moved together with a main spindle 20 to a measurement start position A1, and the reference block 30 is so moved in a Z-axis direction as to across air injected from an air injection nozzle 25, so that a thermal displacement of the main spindle 20 is calculated based on change in pressure measured in the movement. The outer circumference of a tool mounted on the main spindle 20 is brought close to a leading end face of the air injection nozzle 25, and the air is injected to the outer circumference of the tool while rotating the tool at a predetermined position, and the air pressure is measured so that the rotational deflection of the tool is calculated based on the change in the measured pressure.

Abstract: A reference block 30 attached to a housing 20a is moved together with a main spindle 20 to a measurement start position A1, and the reference block 30 is so moved in a Z-axis direction as to across air injected from an air injection nozzle 25, so that a thermal displacement of the main spindle 20 is calculated based on change in pressure measured in the movement. The outer circumference of a tool mounted on the main spindle 20 is brought close to a leading end face of the air injection nozzle 25, and the air is injected to the outer circumference of the tool while rotating the tool at a predetermined position, and the air pressure is measured so that the rotational deflection of the tool is calculated based on the change in the measured pressure.

Abstract: In a state of separating a front end face of an air injecting nozzle 23 from a worked work W by a predetermined interval h, the air injecting nozzle 23 is moved at a constant speed in an X axis direction, injects air from an injecting hole 27a of a nozzle main body 27 and is moved to pass centers O1, O2 of worked holes Wb, Wc of the work W. A variation in a pressure is measured by a pressure measuring unit 30. X axis coordinates of the centers O1, O2 of the holes Wb, Wc, a hole diameter E and a center interval distance D1 are calculated based on coordinates of center points T1, T2 of inclined portions Ld, Lu of a curve Lx of the pressure relative to the measured X axis coordinate.

Abstract: In a state of separating a front end face of an air injecting nozzle 23 from a worked work W by a predetermined interval h, the air injecting nozzle 23 is moved at a constant speed in an X axis direction, injects air from an injecting hole 27a of a nozzle main body 27 and is moved to pass centers O1, O2 of worked holes Wb, Wc of the work W. A variation in a pressure is measured by a pressure measuring unit 30. X axis coordinates of the centers O1, O2 of the holes Wb, Wc, a hole diameter E and a center interval distance D1 are calculated based on coordinates of center points T1, T2 of inclined portions Ld, Lu of a curve Lx of the pressure relative to the measured X axis coordinate.