APPARATUS AND METHOD FOR MEASURING LEAD OF DRUM

PURPOSE:To make precise the evaluation of the shape of a lead by holding a drum rotatably via a mounting part of the drum and measuring the shape of the lead of the drum basing on the mounting part as a reference. CONSTITUTION:A lead measuring device 700 is provided with a drum holding means 12 and a shape measuring means 190. The means 190 has a cam rotating means 13, a measuring element sliding part 14, a moving amount detecting means 15 for the measuring element and, a control means. A rotary shaft 100 of a lower drum 10 is fixed detachably in the drum holding means 12 in the up-and-down direction. When a motor 18 starts rotating in response to an instruction signal from a motor controlling part, the fixed drum 10 is synchronously rotated in a direction A by a cam 19 and a connection unit 17. At this time, the drum 10 is rotated, e.g. by the winding angle of the tape, and the shape or profile of a lead L of the drum 10 to the rotary shaft 100 is measured by a measuring element unit 23.