| 摘要 |
<p>PURPOSE:To accurately ink a center and an outer periphery of a hole of a pull box in which a conduit tube is inserted by so forming a circular ruler that at least part of a contour forms a linear reference side, assuming a circle having a specific diameter in contact with the side thereby to dig out the part and the center of the circumference. CONSTITUTION:At least parts of a contour of a circular ruler 1 form linear reference sides 2a, 2b, and a circle C having a specific diameter in contact with the sides is assumed thereby to dig out a part 3 and a center 4 of the circumference. The circle C has a plurality of circles having common reference sides 2a, 2b and centers arranged on a straight line perpendicular to the sides. A tangential line V perpendicular to the circumferential line and the sides of the circle C is drawn. Further, a recess 5 is provided on one main surface, and a magnet 6 is engaged with the recess 5. A length scale is drawn on a long side of a linear ruler 7 made of rubber magnet. As a result, an inking operation before perforating a conduit tube can be accurately executed in a short time.</p> |
