The diameter of the spring pin mounting hole is the same as the nominal diameter of the spring pin. Where specifying nominal size in decimals, zeros preceding decimal point are. Chart Notes: Nominal pin diameter, recommended drill hole size, go-ring gage, average diameter, slot gap and wall thickness — 12 slotted spring-pin sizes from 1/16″ to 1/2″ (inch, ASME B18. Compressed as it is installed, the pin applies continuous pressure on the sides of the hole wall. This flexibility provides an easier in ing device for ties and timbers.