PURPOSE: To achieve a highly efficient machining by securing a caliper in a brake device such that an opening at a click section will direct upward then machining the inner diameter section of the caliper through said opening by means of a cutter arranged on a spindle of machine.
CONSTITUTION: A caliper 1 is secured to a table 37 for fixing a work with an opening at a click section directing upward. A cutter 24 arranged on a rotary spindle 21 movable up and down can enter/retract freely into/from a cylinder hole 3 through said opening 2. The cutter 24 can approach/retract to/from the cylinder hole 3 while rotating. Consequently, calipers of various specifications can be machined by adjusting the spindle 21 vertically and this machining method is preferable when a numerically controlled machining is employed.