Dowel Pins - Metric
Dowel pins are small, solid steel tubes that resemble traditional wooden dowels.
They are manufactured to a very high tolerance to ensure that they are a precise fit. They are generally used for locking components in place.
Dowel pins are available in metric sizes. The diameter of a dowel pin is obviously the most important dimension but don’t forget to check the length, as unlike wooden dowels they are very awkward to cut to size.
Dowel pins are available in size increments of 1mm diameters.
Metric is the most common thread type in production today. Usually specified as M then a number x another number. This signifies the thread diameter and the length of the fastener.
For example M4 x 30 means that the major thread diameter (the external distance across the outside of the thread) is 4mm and the length is 30mm. Length is usually measured from the underside of the fastener head.