One of the six simple machines, a screw is nothing more than an inclined plane wrapped around a center pole. While today screws come in standard sizes, and typically are tightened by turning clockwise ...

Shoulder screws, also known as shoulder bolts and stripper bolts, are machine screws with an integral shoulder or journal between the head and thread. Although they are not readily available in local ...

News & Views Published: 01 January 1966 Metric Screw Threads Nature 209, 20 (1966) Cite this article ...