Patent ID: 8141263

Claim:
An apparatus for measuring an inside diameter of a hole of a workpiece, comprising: a main body; two probing legs each having a first end and an opposing second end, the first ends pivotedly coupled to the main body at two spaced pivot points respectively; two pressure sensors respectively mounted on the second ends, the pressure sensors configured for generating a pressure signal in response to a reacting force applied thereon by an inner wall of the workpiece in the hole; a step motor configured for driving the probing legs to rotate about the pivot points so as to enable the pressure sensors to abut against the inner wall; a controller unit configured for controlling the step motor to stop driving the probing legs to rotate in response to the pressure signal, the controller unit configured for computing a rotation angle of each probing leg and the inside diameter of the hole according to the rotation angle and a length of each probing leg and a distance between the pivoting points; and a display unit configured for displaying the inside diameter of a hole of a workpiece.