Glossary

A dowel pin is a short, straight, cylindrical pin used to locate, align, or join two parts together with precise repeatability. Instead of carrying most of the load like a bolt, a dowel pin’s main job is positioning—making sure parts go together in exactly the same place every time.

In industrial and fastener terms, dowel pins are usually made from hardened steel, stainless steel, or precision-ground alloys and manufactured to very tight diameter tolerances. They are pressed or slipped into matching holes in mating parts (for example, two plates, a housing and a cover, or a shaft and a hub). When the parts are assembled, the pins keep them from shifting sideways, maintain alignment, and help absorb shear forces, while screws or bolts handle the clamping force.

You’ll see dowel pins used in machinery, automotive assemblies, gearboxes, fixtures, dies, molds, jigs, and precision equipment—anywhere accurate alignment is critical. Common examples include lining up engine components, aligning a machine base to a frame, or ensuring a fixture always returns to the same position on a machine table. They come in metric and inch sizes, in press-fit or slip-fit styles, and sometimes with special ends (chamfered, grooved, or threaded pull-ends) to aid installation and removal.