Taper pin

A tapered pin is a fastener used in mechanical engineering. They are steel rods with one end having a slightly larger diameter than the other. Standard inch-sized tapered pins have a taper on diameter of 1:48 while metric ones have a taper of 1:50. A 1:48 taper means that one end of a 4-foot-long bar (48 inches) will be 1 inch smaller in diameter than the other end, or a 1/4-inch taper over a 1-foot length.

The diameter at the small end of ASME Taper Pins is a function of the length and should be specified as a reference dimension for determining drilled hole size. It shall be computed by multiplying the nominal length of pin by the factor 0.2083 and subtracting the result form the basic pin diameter.