Dowel pins are often used in engineering and machinery applications to accurately locate and align 2 or more components together. As dowel pins are meant to have an interference fit they are manufactured to be slightly oversize from their nominal dimension. Therefore standard .0002 dowel pins are precision ground to be .0002 oversize with a tolerance range of +/- .0001. For example, a ¼” (.250) nominal diameter dowel pin measures oversize from .2501 to .2503. This slight interference measurement compresses the pin when it is driven into the pilot hole, generating considerable friction, holding the pin tightly in place. Dowel pins have a slight chamfer at each end to ease insertion into the receiving hole in the components.
Standard steel dowel pins are manufactured of alloy steel surface hardened to 60 Rockwell C and precision ground .0002 over nominal, ± .0001, with a surface finish and a light oil coating. These pins meet the ASME B18.8.2 specification.