Dowel pins are useful for locating a part into a repeatable, fixed position. They are often used to align parts that need to be more precise than simply lining up screws, as screw holes generally are used for fastening, and not precise alignment. However, pinned joints are not as precise as kinematic couplings, which are used for more precision and repeatability in the optics field and other high tolerance applications. Pinned joints are tolerant to within 1 μm, with a very low cost or complexity to design, which makes them a popular alignment method.
A chart below is provided for metric dowel pin sizes. These tolerances are normally down through the “Limit” option in SolidWorks, indicating the maximum and minimum diameters of the dowel pin holes, with the tolerance being the difference. Standard dowel pin sizes coming soon!
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