Nylon 6/6 Set Screw, Slotted Drive, Flat Point, 1/4"-20, 1-1/2" Length (Pack of 100) Set Screws are often used for holding a pulley, gear, or other parts from turning relative to a shaft.Nylon 6/6 is a general purpose thermoplastic with outstanding resistance to organic chemicals, acids and alkalis. Nylon wears well against other surfaces; it is readily machinable and may be milled, turned and cut with conventional machine tools. It does exhibit some dimensional swelling in wet applications which should be taken into account with its use. Tensile strength of this material is 12,000 psi (pounds per square inch). Common applications for slotted screws include woodworking, although the drive style is not designed to be used with power drivers. Flat Points are useful for minimizing marring and are good for making frequent adjustments. A threaded fastener's size name includes information about the major external diameter, followed by the threads per inch, which indicates if it is coarse or fine. Coarse threads are better when working with brittle materials; they are sturdier and are easier to thread and unthread compared to fine. Coarse threading also allows for thicker coatings and platings.