Not find, perhaps, a car or complicated mechanism which isn’t used ball bearings: they are embedded in devices and engines, airplanes, and tractors, bringing accuracy, reliability and durability. And suddenly — an unexpected metamorphosis: the ball turned into the destroyer, has become a cutting tool. The device, manufactured on its basis, can be used for cutting writing and photographic paper.
This construction is simple. To a rectangular metal base screwed two area. On horizontal shelves rests a plexiglass ruler-clamp. Attached to the vertical guide rod, on which slides the slider with a ball bearing. One of the side surfaces, the latter worn on the sandpaper until the formation of a circular cutting edge.
1 — bearing, 2 — runner, 3 — guide rod, 4 — clamp, 5 — ruler 6 — cutting edge, 7 — the axis of the bearing.
Format cut sheet is controlled by the linear millimeter. Setting the ruler on the desired format, the left hand record sheet clamp, and the right, holding the bearing, cut off the excess.