knurling °ø±¸ ¹× knurling

The knurling tool is a pair of hardened rollers mounted on a handle. Each hard roller has "half" of the knurl: the top roller will have clockwise grooves and teeth; the bottom roller will have them counterclockwise.

Knurling is a manufacturing process, typically conducted on a lathe, whereby a visually-attractive diamond-shaped (criss-cross) pattern is cut or rolled into metal. This pattern allows hands or fingers to get a better grip on the knurled object than would be provided by the originally-smooth metal surface. Occasionally, the knurled pattern is a series of straight ridges or a helix of "straight" ridges rather than the more-usual criss-cross pattern.

This diagram shows the knurling tool pressed against a piece of round section steel. The lathe is set so that the chuck revolves at a low speed. The knurling tool is then pressed against the rotating steel and pressure is slowly increased until the tool produces a pattern on the steel.
The automatic control lever is engaged which starts the automatic traverse of the saddle. As the saddle moves along the bed of the lathe the knurled pattern is pressed into the steel along its length.